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Archives of Virology

Springer Science and Business Media LLC

Preprints posted in the last 30 days, ranked by how well they match Archives of Virology's content profile, based on 14 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.

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Genetic diversity of tomato brown rugose fruit virus in Morocco

Maachi, A.; Donaire, L.; Aranda, M. A.

2026-05-12 microbiology 10.64898/2026.05.11.724243 medRxiv
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Tomato brown rugose fruit virus (Tobamovirus fructirugosum) is an emerging virus that affects tomatoes, capsicum, and chili. Since its first detection in Jordan in 2015, the virus was reported in more than 40 countries across all the continents. In Morocco, the virus was reported for the first time in October 2021. However, its genetic diversity remains unexplored. In this work, we used a collection of tomato fruits from local markets to investigate the variability of the virus in the country. We explored the different pressures acting on the N-terminus of the RNA-dependent RNA polymerase, the movement protein, and the coat protein genes. Then, we used haplotype network analyses to reveal the population structure within the Moroccan isolates and studied their relationships with the ones from the world. We found that genetic diversity is low, which is consistent with the global situation. No signatures of diversifying selection were detected across the analyzed genes. However, the virus sequences from Morocco showed a clear geographic structure, suggesting that geographic factors probably combined with agricultural practices may contribute to shaping the population structure of ToBRFV in Morocco.

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Outbreak of H9N2 avian influenza viruses in lesser rhea in Peru, June-July 2025

Garcia-Glaessner, A.; Crespo-Bellido, A.; Munoz-Saavedra, B.; Juarez, D.; Barrera, P.; Salmon-Mulanovich, G.; Checahuari-Jarata, S. E.; Cruz, D.; Huisa-Balcon, D. X.; Idme, G.; Nelson, M. L.; Lescano, J.; Leguia, M.

2026-05-13 evolutionary biology 10.64898/2026.05.08.723762 medRxiv
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Avian influenza viruses (AIVs) are endemic in the Americas and responsible for outbreaks in both domestic and wild birds that occasionally spill over into humans. We report the first known outbreak of AIV H9N2 in lesser rhea (Rhea pennata), also known as Darwins rhea, in the region of Puno-Peru. The animals in this study lived in an isolated conservation center located in remote highlands above 4,000 m.a.s.l. Between June and July 2025, a total of 46/92 animals were recorded sick, with symptoms including greenish diarrhea (100%), hyporexia (24%), dyspnea (76%), nasal discharge (42%), drowsiness (18%) and isolation from the flock (73%), and 94% later died. Gross pathology exams revealed septicemia characterized by severe hepatitis, pneumonia, tracheitis, enteritis, and encephalitis. Swab and necropsy samples tested positive for Influenza A by PCR and were later identified as H9N2 through whole genome sequencing. We generated complete H9N2 genomes for two individuals. No additional pathogens were found. Phylogenetic analysis across all eight segments revealed that the viruses were low pathogenicity H9N2 AIV strains of North American origin, which indicated this outbreak was a new introduction of the virus into South America. We also performed a comparative mutational analysis and identified multiple mutations previously associated with mammalian host adaptation, increased virulence, increased pathogenicity, and increased virus binding to 2-6 receptors, which may explain the high mortality rates observed despite the supposedly low pathogenicity of the strain. We also identified novel mutations specific to rhea viruses that will need to be experimentally validated. This is the first report of a natural H9N2 systemic infection in an avian host, highlighting a need for increased surveillance efforts for zoonotic influenza viruses with pandemic potential. Author SummaryAvian influenza viruses (AIVs) are endemic in the Americas and cause more than 7,600 infections annually in domestic and wild birds worldwide each year. We report detection of AIV H9N2 in lesser rhea during an outbreak that occurred in June-July 2025 in the Andean highlands of Puno in Peru. Multiple sick animals were reported with symptoms of respiratory and gastrointestinal disease and 94% of them later died. Samples collected tested positive for Influenza A and they were subtyped as H9N2 of low pathogenic origin from North America. This is the third time H9N2 enters South America from North America, presumably through wild birds, some of which migrate along the Pacific Flyway. Comparison with other H9N2 sequences revealed a total of 44 mutations of interest that may explain the elevated death rates observed. Surveillance in wild birds remains patchy at best and needs to be strengthened in order to prevent spillover events into other animals, including humans.

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Molecular epidemiology of the globally spreading genetic lineage IV of peste des petits ruminants virus

Courcelles, M.; Tounkara, K.; Mantip, S.; Niang, M.; Kounta Sidibe, C. A.; Sery, A.; Dakouo, M.; Luka, P. D.; Adedeji, A.; Shamaki, D.; Muhammad, M.; Ali, Y. H.; Saeed, I. K.; Awuni, J.; Odoom, T.; Tetteh, P. A.; Yingar, D. T.; Wade, A.; Dickmu, S.; Diddi, A.; Shawash, H.; Couacy-Hymann, E.; Mathurin, K. Y.; Ouled Ahmed Ben Ali, H.; Ben Hassen, S.; hadouchi, s.; Alm-ajali, A.; Settypalli, T. B. K.; Lamien, C. E.; Salami, H.; Rassoul, S.; Asnaoui, M.; Cetre-Sossah, C.; Guendouz, S.; Kwiatek, O.; Libeau, G.; Dundon, W. G.; Bataille, A.

2026-05-18 evolutionary biology 10.64898/2026.05.18.725933 medRxiv
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Peste des petits ruminants (PPR) is a highly contagious viral disease of small ruminants caused by the peste des petits ruminants virus (PPRV), which is classified into four distinct genetic lineages (I-IV). A critical concern in the recent epidemiological history of PPRV is the rapid and widespread expansion of lineage IV (LIV) across West Africa over the past decade. This dominance suggests a potential adaptive advantage of circulating LIV strains in the regions current epidemiological context. In this study, we obtain the genome sequence of 26 new PPRV samples, including historical (pre-2000) and many recent African LIV isolates, offering the first opportunity to investigate the evolutionary history of LIV in Africa and identify genetic events potentially associated with its recent spread. Phylogenomic analyses implemented on a dataset of 167 curated PPRV genome sequences reveal that the most ancestral LIV group comprises strains circulating in Sub-Saharan Africa (designated clade LIVssa), providing robust evidence for an African origin of lineage IV. Our results further indicate that PPRV strains linked to the recent West African expansion of LIV belong to a specific LIVssa subgroup, termed NigB. We identified multiple signatures of selection pressure within the LIVssa sublineage, particularly in the NigB cluster. Several amino acid substitutions unique to LIVssa or NigB were detected, some of which may impact protein function and warrant prioritised investigation. Additional genomic data are required to confirm the association between the NigB group and the ongoing spread of LIV in West Africa. The evolutionary adaptations observed in LIVssa - potentially enhancing transmission efficiency, host range or pathogenicity - could undermine current disease control strategies in regions where PPR poses significant threats to food security and local economies. Author SummaryPeste des petits ruminants virus (PPRV) infects sheep and goats across Africa, Middle East, Asia and Europe, causing disease with major impact on global economy and food security. One genetic lineage of PPRV, called lineage IV (LIV), is at the origin of most recent expansion of the distribution of the disease, including replacement of other lineages in areas of African where PPRV is historically present. Here, we generated genome sequences from PPRV LIV isolates from different dates and places to study the evolution of this genetic lineage and explore whether its recent spread can be associated with the appearance of new mutations in the virus genome. Our results provide evidence that the PPRV LIV originated in Sub-Saharan Africa and identify mutations present only virus isolates currently spready in new regions of Africa. Further research should investigate the impact of these mutations on protein functions and capacity of transmission of PPRV.

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Genome-wide identification of rhabdoviral sequences in alfalfa (Medicago sativa L.)

Grinstead, S.; Nemchinov, L. G.

2026-05-22 genomics 10.64898/2026.05.20.726541 medRxiv
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We recently reported the identification of endogenous viral elements (EVEs) originating from the Caulimoviridae family within the alfalfa (Medicago sativa L.) genome. Our subsequent identification of ubiquitous rhabdoviral elements in infected and healthy alfalfa tissues by high throughput sequencing prompted us to suggest that the alfalfa genome might be populated with integrated rhabdoviruses as well. Bioinformatics analysis using 26 publicly available alfalfa genomes proved the suggestion accurate. We found multiple non-retroviral segments of the Rhabdoviridae family belonging to the genera Betanucleorhabdovirus and Betacytorhabdovirus that appeared to be stable constituents of the host genome. In that capacity they could potentially acquire functional roles in alfalfas development and response to environmental stresses. We believe this study reveals the first documented case of rhabdoviruses integrated into the alfalfa genome.

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G4 Eurasian avian-like H1N1 swine influenza viruses exhibit enhanced pathogenicity potential in mice and pigs

Jiao, J.; Ding, J.; Sun, Z.; Chi, C.; Jiang, S.; Chen, N.; Zheng, W.; Chen, C.; Su, W.; Ding, X.; Zhu, J.

2026-05-12 microbiology 10.64898/2026.05.12.724537 medRxiv
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Currently circulating swine influenza viruses (SIVs) mainly include H1N1, H1N2, and H3N2 subtypes. In this study, two G4 genotype Eurasian avian-like (EA) H1N1 SIVs were isolated from 556 samples collected between 2023 and 2026. A systematic analysis was conducted on the two EA H1N1 isolates (FYD30 and YZF69) to assess their pandemic potential. The hemagglutinin (HA) proteins of both H1N1 viruses possessed residues 225E and 228S, indicating enhanced affinity for human-like -2,6-linked sialic acid receptors, which was confirmed by receptor-binding assays. Polymerase activity tests demonstrated that the two SIVs exhibited significantly higher activity in mammalian cells, relative to avian cells, which is consistent with the efficient replication in mammalian cells. Challenge experiments revealed that both H1N1 caused significant pathogenicity in mice and pigs, with YZF69 exhibited higher virulence than FYD30. The higher virulence of YZF69 may be attributed to its molecular features, including the NP Q357K mutation, and an additional glycosylation site in HA. In conclusion, currently circulating EA H1N1 SIVs have acquired key molecular signatures of mammalian adaptation, exhibit enhanced virulence in mammals, and continue to undergo extensive reassortment driven by international swine trade. These findings highlight the potential pandemic risk of SIVs and underscore the urgent need for strengthened surveillance.

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Pathogenesis and immune responses to Eurasian avian like H1N1 and influenza D virus in pigs.

VATS, A.; Yang, L.; Rostami, E. S.; Hatton, C.; Briggs, E.; Freimanis, G.; Dowling, T.; Reeth, K. v.; Paudyal, B.; Salguero, F. J.; Gerner, W.; Tchilian, E.

2026-05-07 immunology 10.64898/2026.05.05.722908 medRxiv
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Eurasian avian like H1N1 (EAavH1N1) and influenza D viruses (IDV) with their ongoing evolution and zoonotic potential are a serious threat to animal and human health. Using experimental infection of pigs, we characterized and compared their pathogenesis, and immune responses. EAavH1N1 induced rapid viral clearance, early immune activation, including robust systemic and mucosal antibody responses and increased IFN{gamma} and TNF production. This heightened immune response was associated with more severe pathology of the upper and lower respiratory tract. In contrast, IDV infection resulted in prolonged viral shedding and higher viral titres, with delayed and attenuated cellular immune responses. Single cell transcriptomic analysis of lung further indicated early and persistent suppression of antiviral and innate immune pathways during IDV infection. These findings demonstrate that EAavH1N1 and IDV exhibit distinct viral kinetics, immune activation profiles, and lung responses, providing insight into differences in transmission dynamics, disease severity, and immune control among influenza virus types in swine.

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Insect pests survey of Prosopis juliflora, Afar rangeland, Ethiopia

Mekonnen, B. B.; Ali, S. E.; Lemma, E. G.

2026-05-05 ecology 10.64898/2026.05.04.722396 medRxiv
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Prosopis juliflora is an invasive alien plant species and a problematic weed that poses significant ecological and socio-economic challenges in Ethiopia, particularly in the Afar rangelands. The study explored the diversity and effects of insect herbivores communities feeding on the flowers and pods of P. juliflora to determine their role in limiting reproductive success across three selected ecological sites: Amibara, Gewanne, and Aysayita. A total of 118 adult insect specimens were collected between January and November 2021 using a sweep net and hand collection methods. Community structure, analysis via the Shannon Wiener diversity index, strongly influenced damage pattern. Amibara exhibited the highest insect diversity resulting in significant reproductive damage, including 5.98% of flower loss and 10.39% pods tunneling, primarily caused by Chrysomelidae and Pyralidae. Conversely, Gewanne was showed lower diversity, but higher sap-sucking (13.39 % shriveled pods; 5.11 % flower curling) were caused by Aphididae. Overall, 18.41 % of the pods, and 11.59 % of the flowers were exhibited insect related injury. These finding confirm that more internal seed predation and nutrient depletion were revealed significantly reduce viable seed production. The result was suggested that natural insect communities currently function as partial biological control agents. This indicates strong potential for developing integrated biological control strategies to manage P. juliflora invasion in Ethiopia rangelands.

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Reception Of Respectful Maternity Care And Their Determinants Among Postpartum Mothers During Institutional Childbirth In East Wollega Zone Hospitals, West Oromia, Ethiopia, 2026.

Ahmed, T. H.; Abeya, S. G.; Chaka, E. E.

2026-05-21 obstetrics and gynecology 10.64898/2026.05.18.26353527 medRxiv
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Respectful maternity care [RMC] comprises the primary components of high-quality maternal health services. Evidence on RMC levels and determinants in Ethiopia is still inadequate. This study aimed to examine the reception and its determinants among postnatal women in government hospitals in the East Wallaga Zone, West Oromia. An institution-based cross-sectional study was conducted from June to October 2025, within seven days post-delivery. A structured questionnaire based on the WHO RMC tools was used. The total RMC score proved robust reliability [Cronbachs = 0.808] and was organized using the 75th-percentile threshold. Factor analysis revealed basic RMC dimensions, while logistic regression was used to identify predictors of a promising RMC experience. This study presented that only 46.8% of postpartum mothers received adequate RMC, with significant gaps in care. The main deficiencies comprised poor provider self-introduction, failure to call women by name, and infrequent communication and consent practices. Three key RMC dimensions were identified: privacy and consent, explanation and permission, and respectful communication. Using multivariate analysis, interpersonal caring practices were robust predictors of positive RMC experiences. Explaining procedures with possible events, maintaining privacy, obtaining consent, prompt responsiveness, provider self-introduction, and calling mothers by name were significantly associated factors. Sociodemographic and maternal reproductive factors were not significantly associated after adjusting for confounders. Finally, fewer than half [46.6%] of mothers experienced adequate RMC, which indicated major gaps in woman-centered care. Improving respectful interpersonal communication, informed consent, and maintaining privacy should be prioritized to boost the quality of maternal healthcare in the study area.

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A tomato fruit blotch viral replicon defines minimal requirements for cell autonomous replication and identifies functional RNA4-encoded movement and silencing suppression activities

Miotti, N.; Bono, F.; Ratti, C.; Casati, P.; Turina, M.; Ciuffo, M.

2026-05-21 microbiology 10.64898/2026.05.21.726790 medRxiv
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Tomato fruit blotch virus (ToFBV) is an emerging multipartite positive-sense RNA virus associated with blotchy symptoms on tomato fruits and classified within the genus Blunervirus (family Kitaviridae). Despite its increasing agricultural relevance, the study of ToFBV has been hindered by the lack of mechanical transmissibility and the difficulty in reproducing infections under controlled conditions. In this work, we report a preliminary step toward the development of the first infectious agroclone system for ToFBV, based on full-length cDNA copies of its four genomic RNAs. We demonstrate that the cloned viral genome is capable of initiating cell autonomous replication in Nicotiana benthamiana, as indicated by the accumulation of negative-sense RNA intermediates in infiltrated tissues. To further validate the system, RNA3 was engineered to express GFP, enabling visualization of infection foci and confirming active viral replication in both N. benthamiana and tomato. Functional assays of RNA4-encoded proteins demonstrated that it encodes a movement protein capable of complementing movement-deficient viral vectors and a putative suppressor of post-transcriptional gene silencing (PTGS). Together, these results establish a versatile reverse genetics platform for ToFBV, providing new insights into the replication and functional organization of blunerviruses and enabling future studies on virus-host interactions, pathogenicity, and control strategies.

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Genome-wide computational prediction of miRNAs encoded by influenza A virus (H3N2) predicts target genes involved in pulmonary and antiviral innate immunity

Siddiqi, M. A.; Kumar, H.; Mazumder, M.

2026-05-18 bioinformatics 10.64898/2026.05.18.725090 medRxiv
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Influenza A virus (IAV) causes significant morbidity and mortality worldwide. Understanding how viral RNAs may regulate host genes through microRNA-like mechanisms can clarify pathogenesis and reveal therapeutic targets. In this study, we screened all eight IAV H3N2 RNA segments (PB2, PB1, PA, HA, NP, NA, M, and NS) using an ab initio computational pipeline; five segments (PB2, PB1, PA, HA, and M) met the VMir scoring threshold for further analysis, while NP, NA, and NS were excluded due to low pre-miRNA scores. Mature miRNAs were identified using MatureBayes, and target genes in the human genome were predicted with the miRDB server. From these targets, we selected two genes per qualifying segment (10 genes total) based on their functional relevance to influenza infection and supporting literature; all selected genes are unique to their respective segment. We identified 10 segment-specific target genes (IFNL1, DDX60, SAMHD1, MAVS, IRF4, BIRC2, AGO1, MAP3K1, NOD1, and TNFAIP1) and one common target across all five analyzed segments (CADM2). Gene Ontology and pathway analyses showed enrichment in interferon signaling, RIG-I-like receptor pathways, antiviral restriction, RNA interference, and inflammatory responses. Literature supports roles for these genes in pulmonary and antiviral innate immunity. Our findings provide a basis for experimental validation and may help the research community better understand influenza virus pathogenesis and identify novel therapeutic candidates. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=111 SRC="FIGDIR/small/725090v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@2b14adorg.highwire.dtl.DTLVardef@5a9b2eorg.highwire.dtl.DTLVardef@81ffc1org.highwire.dtl.DTLVardef@be119b_HPS_FORMAT_FIGEXP M_FIG C_FIG

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Prevalence, Genotyping, and Mutational Analysis of Hepatitis B Virus in HIV-Infected Patients on Antiretroviral Therapy in Nairobi, Kenya

Ochieng, L. A.; Macharia, R. W.; Mwau, M.

2026-05-08 hiv aids 10.64898/2026.05.06.26352536 medRxiv
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BackgroundHepatitis B virus infection remains a major public health challenge, particularly among people living with human immunodeficiency virus, due to shared transmission routes and the potential for accelerated liver disease progression. Molecular characterization of circulating HBV strains is essential for understanding viral epidemiology, mutation patterns, and implications for diagnostics and vaccination. MethodsThis study investigated the prevalence of hepatitis B infection and molecular characteristics of the hepatitis B virus surface gene among HIV-infected individuals receiving antiretroviral therapy in Nairobi County, Kenya. Plasma samples were screened for hepatitis B surface antigen using enzyme-linked immunosorbent assay. Hepatitis B viral DNA was extracted from HBsAg-positive samples and the surface gene region amplified by polymerase chain reaction. Amplified products were subjected to Sanger sequencing. Sequence assembly, genotype determination, and mutation analysis. ResultsThe prevalence of HIV/HBV co-infection among HIV-positive individuals was determined to be 8.97%. Genotype analysis revealed the circulation of HBV genotype A (sub-genotypes A1 and A4) and genotype D (sub-genotypes D4 and D10) among the studied population. Amino acid sequence analysis of the major hydrophilic region of the surface gene identified several mutations, with R122K and Y134F being the most frequently observed substitutions. ConclusionHepatitis B infection remains prevalent among HIV-infected individuals receiving antiretroviral therapy in Nairobi County. The circulation of multiple hepatitis B virus genotypes and the presence of mutations within the surface gene highlight the importance of continuous molecular surveillance to monitor viral evolution and its potential implications for hepatitis B virus diagnosis, vaccination strategies, and clinical management in HIV-infected populations

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Widespread circulation of West Nile and Usutu viruses in sedentary and migratory avifauna: A Two-Year Study (2024-2025) of active surveillance in South of France

Beaubaton, R.; Revel, J.; Pigeyre, L.; Lepeule, A.; Joly, J.; de Franceschi, C.; Charmantier, A.; Vollot, B.; Simonin, Y.

2026-05-21 microbiology 10.64898/2026.05.21.726855 medRxiv
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West Nile virus (WNV) and Usutu virus (USUV) are neurotropic Orthoflaviviruses sharing a similar enzootic transmission cycle primarily involving Culex pipiens mosquitoes as vectors and birds as amplifying hosts. First identified in Africa, both viruses established endemicity across Europe over the past two decades, most likely introduced and spread by migratory bird species along Mediterranean flyways. In avian species, infection outcomes range from subclinical to fatal neuroinvasive disease, varying by viral strain, host immunity, and species susceptibility. Southern France emerges as a key hotspot for the circulation of these viruses, supported by diverse avian habitats conducive to year-round viral maintenance. This study investigated the prevalence of WNV and USUV in more than 2500 sedentary and migratory wild birds from these regions during 2024-2025 using molecular surveillance. Samples were collected using mist net and bird boxes, across multiple passerine and non-passerine taxa, spanning wetlands, urban fringes, and agricultural zones. Our analyses revealed widespread viral circulation across diverse species, mainly among passerines such as great tits, house sparrows, and barn swallows with USUV detected at higher rates than WNV in both study years. Overall prevalence was markedly higher in 2024 than in 2025, potentially reflecting climatic or ecological drivers. Migratory individuals likely seed viral introductions during seasonal passages, whereas resident populations sustain local enzootic cycles, facilitating overwintering persistence. These results highlight the pivotal role of mixed avifauna in arbovirus dynamics within Mediterranean Europe and emphasize the necessity for integrated, year-round surveillance targeting high-risk species and habitats. Enhanced monitoring will aid in predicting spillover risks and informing vector control strategies to mitigate zoonotic threats.

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Suspected rabies exposure among animal-bite human cases in Busia district, Uganda: Prevalence, associated factors and delayed post-exposure care-seeking. A cross-sectional study

Wagaba, D.; Nabukenya, I.; Kizza, J.; Unith, H.; Kanyange, A.; Turyahabwe, C.; Kibuuka, H.; Mugisha, D.; Ogola, S. P.; Nabidda, S.; Kisakye, L. K.; Kalyango, J.

2026-06-01 epidemiology 10.64898/2026.05.29.26354408 medRxiv
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Background Rabies is a zoonotic neglected public health problem associated with animal bites, especially domestic carnivores claiming 59,000 deaths annually predominantly in developing countries of Africa and Asia. There is a high risk of exposure among rural communities endemic with animal rabies where adoption of prevention strategies is minimal. This study determined the prevalence of suspected rabies exposure, associated factors, and delayed post-exposure care-seeking among animal-bite human cases in Busia district, Uganda. Methods: This was a cross-sectional study that involved 332 consecutively sampled animal bite human cases that occurred within the period 2023 to 2024. Data for the bite cases from records were collected using a data abstraction tool. In addition, interviewer-administered semi-structured questionnaires were used to collect data on sociodemographic, animal-related and environmental characteristics. Approximate bite locations were collected using Global Positioning System (GPS) coordinates via Kobo collect. Analysis was carried out in STATA 17 using mixed effects modified Poisson regression for factors associated with suspected rabies exposure. Results: The median age of the bite cases was 18 (IQR: 9-36) with the male gender predominantly affected. The prevalence of suspected rabies exposure was 53.6% (95% Confidence interval - CI: 46.8-60.3). Factors associated were urban versus (vs) rural residence (adjusted prevalence ratio-aPR: 1.04, 95%CI: 1.00-1.08), being bitten by a stray animal (aPR: 1.28, 95% CI: 1.22-1.35) and wild animal (aPR: 1.22, 95% CI: 1.14-1.30) vs domestic animal, vaccination status of the biting animal i.e. vaccinated vs unvaccinated (aPR: 0.76, 95% CI: 0.69-0.85), provoked vs unprovoked bites (aPR: 0.82, 95% CI: 0.79-0.86), and distance to nearest river ([&ge;]5km) vs <5km (aPR: 0.93, 95% CI: 0.87-0.99). The prevalence of delayed post-exposure seeking was 23.0% (95% CI: 16.5-31.1) among the suspected rabies exposures. Conclusion: The study reveals a high prevalence of suspected rabies exposure. Factors associated are multidimensional i.e. are of human, animal and environmental origin. The one health paradigm should be emphasized during routine surveillance of rabies-related cases. The study observed that 1 in 5 bite cases delayed to seek care post bite exposure. We recommend collaborations between sectors, routine vaccination and awareness campaigns, and monitoring of wild carnivore populations and environmental dynamics in rabies-related surveillance.

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Description of Rickettsia senegalensis sp. nov.: a new Rickettsia species detected worldwide

Labarrere, C.; Houmenou, C. T.; Fournier, P.-E.; Fenollar, F.; Mediannikov, O.

2026-05-05 microbiology 10.64898/2026.05.02.721834 medRxiv
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Rickettsia senegalensis is a novel Rickettsia species isolated from cat fleas, Ctenocephalides felis, in Senegal. Genomic analysis confirmed its status as a distinct species, placing it within the transitional Rickettsia group, within a R. felis cluster. Furthermore, rickettsial genes identical to those of Rickettsia senegalensis had been already identified in several hematophagous arthropods, including fleas and ticks parasitizing various hosts such as cats, dogs, opossums, and rodents in tropical and subtropical regions all over the world. It has also been detected in cat tissues, suggesting a potential host-pathogen association. Here we formally propose Rickettsia senegalensis sp. nov. as a new species. The type strain of this species is strain PU01-02T (= CSUR R184T = DSM 28250T). Strain PU01-02T grows aerobically in XTC-2, SF9, and LD652 cell lines at 28 {degrees}C in a CO2-free atmosphere. The genome of strain PU01-02T has a size of 1.62 Mb and a G+C content of 33.2%. RepositoriesThe genome sequence of Rickettsia senegalensis sp. nov. strain PU01-02T has been deposited in GenBank under accession number JBVYTQ000000000, and the rrs, gltA, ompB and sca4 gene sequences under accession numbers KF666476, KF666472, KF666470, KF666474, respectively. The plasmid accession numbers are PZ272915, PZ272916, and PZ272917, for pRS01, pRS02 and pRS03, respectively.

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Increasing frequency of secondary dengue infections in sequential outbreaks (2016-2024). Clinical impact and diagnostic challenges.

Espindola, S. L.; Pereson, M. J.; Lema, J. M.; Kachuk, A.; Carballo, G.; Aloisi, N.; Badano, M. N.; Miretti, M.; Di Lello, F. A.; Bare, P. C.

2026-06-01 infectious diseases 10.64898/2026.05.29.26354405 medRxiv
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Successive dengue virus (DENV) outbreaks can progressively reshape population immunity influencing disease expression and diagnostic performance. Objectives The aim was to evaluate the impact of secondary infections across sequential outbreaks on clinical severity, serotype dynamics and diagnostic concordance. Methods This retrospective study analyzed 976 febrile-stage samples from three sequential outbreaks in Misiones, Argentina. For serotyping and clinical analyses, 869 viremic samples confirmed by at least one direct method were included (2016: n=512; 2019: n=148; 2024: n=209). Additionally, 318 samples, including 107 non-viremic cases, were used to compare NS1 rapid diagnostic tests (NS1 Ag) and RT-PCR. Viral serotyping and clinical and laboratory markers of disease severity were evaluated. Results Secondary infections increased from 31.05% (2016) to 43.24% (2019) and 53.87% (2024) (p<0.0010). Serotype distribution shifted from DENV-1 predominance in 2016 (95.12%), DENV-1/DENV-4 co-circulation in 2019 (60.71%/39.29%), and DENV-2 predominance in 2024 (97.60%). Secondary infections were associated with more severe disease manifestations, particularly in 2024, with higher hematocrit (p=0.0120) and hemoglobin (p=0.0080), lower white blood cells (p=0.020) and platelet counts (p=0.0030), and elevated AST (p=0.0007) and ALT (p=0.0130). Concordance between NS1 Ag and RT-PCR was lower in secondary infections (k=0.457 vs k=0.759, p=0.0013). Conclusions The rising frequency of secondary infections may affect both clinical severity and diagnostic performance during outbreaks. The clinical impact was more evident in 2024, likely associated with the introduction of a new serotype. These findings highlight the need for optimized surveillance and diagnostic strategies to improve case detection and patient management during epidemics.

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Potential association of HLA and KIR genetic profiles with resistance to HIV infection in high-risk men who have sex with men

Ossa-Giraldo, A. C.; Blanquiceth, Y.; Florez-Alvarez, L.; Penata, A.; Bustamante, J.; Marin, N. D.; Rojas, W.; Hernandez, J. C.; Zapata, W.

2026-05-03 hiv aids 10.64898/2026.04.30.26352161 medRxiv
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Understanding the immune response against HIV-1 and the natural resistance exhibited by HIV-exposed Seronegative Individuals (HESN) offers the possibility of proposing new control strategies. Several studies suggest an important role of HLA and KIR genes in protecting against HIV-1 infection. Moreover, there is an important gap in the knowledge of these genetic factors in seronegative Latin American men who have sex with men (MSM), a population largely underrepresented in HIV immunogenetic studies. This study aimed to identify HLA and KIR genetic profile associated with potential resistance to HIV-1 acquisition, in a cross-sectional study including a cohort of 60 HIV-1-seronegative Colombian MSM at low and high risk of HIV-1 infection. The high-risk group showed a higher frequency of the HLA-B*18 allele, and a lower frequency of the HLA*B35, which have been previously associated with protection and susceptibility to HIV-1 infection respectively. Likewise, the high-risk group exhibited a low frequency of Bx haplotypes, a higher frequency of one AA haplotype and differences in KIR gene profile, with a low frequency of the inhibitory KIR2DL5 and both activating KIR2DS1, KIR2DS2 and KIR2DS5 genes. These findings suggest that host immunogenetic factors may contribute to resistance to HIV-1 acquisition in highly exposed individuals.

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First record of the subfamily Eucerotinae (Hymenoptera: Ichneumonidae) from the mainland Afrotropics, with a description of a new species

Hopkins, T.; Nascimento, A.; Santos, B. F.; Hovorka, T.; Sääksjärvi, I. E.; Österman, E. M.

2026-05-14 zoology 10.64898/2026.05.11.724332 medRxiv
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The ichneumonid subfamily Eucerotinae has been thought to be almost absent from the tropics, with the only known Afrotropical species found in Madagascar. We report the subfamily to be present in the mainland Afrotropics, and describe a new species, Euceros species 1 from Uganda and Cameroon (name not yet shown in preprint). The subfamily had likely not been observed in the mainland Afrotropics before due to low abundances and insufficient sampling. More Eucerotinae likely remain to be discovered in tropical Africa and Asia, although tropical America may genuinely have few eucerotine species. Much more extensive sampling will be needed before it is possible to make confident estimates of how eucerotine diversity is distributed globally.

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Hepatitis E virus seroprevalence in South Africa from a multi-site study among HIV-negative and HIV-positive adults and age-stratified children (2-17 Years)

Saluja, T.; Telele, N. F.; Hellstrom, E.; Mitha, E.; Nchabeleng, M.; Baiden, R.; D'Cor, N. A.; Vemula, S.; Park, J. Y.; Yang, L.; Lee, J.; Kim, D. R.; Park, S.; Aspinall, S.; Pan, H.; Shih, J. W.-K.; Lynch, J.

2026-05-03 epidemiology 10.64898/2026.05.01.26352167 medRxiv
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BackgroundHepatitis E virus (HEV) seroprevalence varies by age and geography. Data on HEV seroprevalence across age groups and among people living with HIV (PLWH) in South Africa is scarce. MethodsWe conducted a prospective multi-site assessment of anti-HEV IgG seroprevalence on 859 South African participants enrolled at three clinical research centres including Newtown Clinical Research Centre in Johannesburg, Be Part Research in Mbekweni, Paarl, Western Cape, and Mecru Clinical Research Unit in Garankuwa, Pretoria. Participants comprised adults aged 18 - 45 years (PLWH, n = 178 and HIV-negative, n = 232), and children aged 2-17 years (n = 449). Anti-HEV IgG serostatus and antibody titer were measured using a commercial ELISA kit and a WHO reference standard. Seroprevalence was assessed by site, age group, sex, and HIV status. ResultsOverall anti-HEV IgG seroprevalence was 18.0% (95% CI: 15.6-20.8). Adults had the highest seroprevalence (27.3% among all adults; 29.2% among PLWH and 25.9% in HIV-negative adults), while adolescents aged 12-17 years had the lowest (6.9%), and young children aged 6-11 years and 2-5 years had 10.3% and 13.0%, respectively. Adults had significantly higher odds of seropositivity than children (aOR 2.8, 95% CI: 1.5-5.5, p = 0.002). A significant site-specific variation was also observed among healthy adults and adolescents: Newtown Clinical Research Centre (23.0% and 14.0%) and Be Part Research (34.5% and 7.3%) had higher seroprevalence compared with those from Mecru Clinical Research Unit (17.2% and 1.5%, p = 0.0499 and 0.0262, respectively). A higher mean antibody titer observed in younger children aged 2-5 years (5.06 IU/mL), compared with adults (0.88 IU/mL among PLWH and 0.68 IU/mL among HIV-negative adults), and with older children (2.02 IU/mL in those aged 6-11 years and 0.67 IU/mL in those aged 12-17 years). ConclusionsHEV seroprevalence in South Africa was highly heterogeneous, varying markedly by age group and study site. These findings highlight the need for strengthened, integrated HEV surveillance to better define transmission patterns and to inform evidence-based considerations for prevention of infection.

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Genomic characterization and therapeutic potential of five broad-spectrum lytic bacteriophages against multidrug-resistant avian pathogenic Escherichia coli (APEC)

Midha, T.; Vishakha, V.; Baranwal, S.

2026-05-22 microbiology 10.64898/2026.05.21.727054 medRxiv
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Colibacillosis, caused by Avian Pathogenic Escherichia coli (APEC), result in substantial economic losses in global poultry production. The emergence of multidrug-resistant (MDR) APEC poses zoonotic risks through horizontal transfer of antimicrobial resistance (AMR) genes. Bacteriophage therapy emerges as a safe alternative to antibiotherapy; however, comprehensive characterization of phages targeting MDR-APEC from diverse geographical regions remains limited. We isolated five lytic bacteriophages from poultry fecal samples collected from five Indian states and characterized them through morphological analysis, physiological stability testing, whole-genome sequencing, and in vivo efficacy assessment. Host range was determined against APEC isolates, and therapeutic potential was validated in Galleria mellonella infection model. All five phages showed Myovirus-like morphology and stability across physiologically relevant temperatures (up to 55-70{degrees}C) and pH conditions (3-11). Their genome size ranges from 170 to 356 kb, belonging to three distinct genera; Dhakavirus, Gaprivervirus, and Asteriusvirus. Genomic analysis confirmed absence of antimicrobial resistance, virulence, toxin, or lysogeny genes. 51 APEC strains were isolated, of which 23 (45.1%) were MDR. Individual phages lysed 37-51% of tested APEC and 17-39% of MDR strains. Three Escherichia phages (fBSZT1, fUAMT1, fPKPT2) significantly improved larval survival to 60-80% at MOI 10 in G. mellonella infection models compared to untreated controls. This study establishes a well-characterized phage bank targeting MDR-APEC strains, providing foundation for developing phage-based interventions to reduce antibiotic dependency and mitigate AMR transmission risks under One Health framework.

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Methodological Evaluation and Data Resource for Andes Virus Sequencing Preparedness

Doherty, R.; Lewandowski, K.; Fenwick, A.; Everall, I.; Morley, D.; Hartman, H.; Staplehurst, S.; Kent, C.; Loman, N. J.; Quick, J.; Pullan, S. T.

2026-05-16 genomics 10.64898/2026.05.15.725146 medRxiv
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As part of preparedness activities supporting pathogens classified under the UK High Consequence Infectious Diseases (HCID) framework, we previously evaluated both a whole-genome tiling amplicon sequencing scheme and a pan-viral hybridisation capture approach (TWIST-CVRP) for sequencing Andes virus (ANDV). In light of the recent outbreak, we make available viral sequencing datasets generated using a historical ANDV isolate (Chile, 1997). In addition, we provide an evaluation of tiling amplicon scheme performance and present recommended primer updates informed by in silico comparison with the recently released outbreak genome. These datasets are intended to support benchmarking, validation, and optimisation of bioinformatic pipelines across the community.