Virology Journal

BackgroundThe pandemic of coronavirus disease 2019 (COVID-19) has become the first concern in international affairs as the novel coronavirus (SARS-CoV-2) is spreading all over the world at a terrific speed. The accuracy of early diagnosis is critical in the control of the spread of the virus. Although the real-time RT-PCR detection of the virus nucleic acid is the current golden diagnostic standard, it has high false negative rate when only apply single test. ObjectiveSummarize the baseline characteristics and laboratory examination results of hospitalized COVID-19 patients. Analyze the factors that could interfere with the early diagnosis quantitatively to support the timely confirmation of the disease. MethodsAll suspected patients with COVID-19 were included in our study until Feb 9th, 2020. The last day of follow-up was Mar 20th, 2020. Throat swab real-time RT-PCR test was used to confirm SARS-CoV-2 infection. The difference between the epidemiological profile and first laboratory examination results of COVID-19 patients and non-COVID-19 patients were compared and analyzed by multiple logistic regression. Receiver operating characteristic (ROC) curve and area under curve (AUC) were used to assess the potential diagnostic value in factors, which had statistical differences in regression analysis. ResultsIn total, 315 hospitalized patients were included. Among them, 108 were confirmed as COVID-19 patients and 207 were non-COVID-19 patients. Two groups of patients have significance in comparing age, contact history, leukocyte count, lymphocyte count, C-reactive protein, erythrocyte sedimentation rate (p<0.10). Multiple logistic regression analysis showed age, contact history and decreasing lymphocyte count could be used as individual factor that has diagnostic value (p<0.05). The AUC of first RT-PCR test was 0.84 (95% CI 0.73-0.89), AUC of cumulative two times of RT-PCR tests was 0.92 (95% CI 0.88-0.96) and 0.96 (95% CI 0.93-0.99) for cumulative three times of RT-PCR tests. Ninety-six patients showed typical pneumonia radiological features in first CT scan, AUC was 0.74 (95% CI 0.60-0.73). The AUC of patients age, contact history with confirmed people and the decreased lymphocytes were 0.66 (95% CI 0.60-0.73), 0.67 (95% CI 0.61-0.73), 0.62 (95% CI 0.56-0.69), respectively. Taking chest CT scan diagnosis together with patients age and decreasing lymphocytes, AUC would be 0.86 (95% CI 0.82-0.90). The age threshold to predict COVID-19 was 41.5 years, with a diagnostic sensitivity of 0.70 (95% CI 0.61-0.79) and a specificity of 0.59 (95% CI 0.52-0.66). Positive and negative likelihood ratios were 1.71 and 0.50, respectively. Threshold of lymphocyte count to diagnose COVID-19 was 1.53x109/L, with a diagnostic sensitivity of 0.82 (95% CI 0.73-0.88) and a specificity of 0.50 (95% CI 0.43-0.57). Positive and negative likelihood ratios were 1.64 and 0.37, respectively. ConclusionSingle RT-PCR test has relatively high false negative rate. When first RT-PCR test show negative result in suspected patients, the chest CT scan, contact history, age and lymphocyte count should be used combinedly to assess the possibility of SARS-CoV-2 infection.

Seasonal influenza (flu) is an underappreciated source of disease morbidity and mortality worldwide. While vaccination remains the cornerstone of influenza prevention, common measures practiced during the COVID-19 pandemic such as social distancing, the use of protective face masks, and frequent hand washing are rarely utilized during flu season. In this investigation, we examined the effect of these preventative measures in decreasing influenza burden this year. We examined three countries with major COVID-19 outbreaks i.e. China, Italy and the United States, and compared the flu activity this year to the average of the last 4 years (2015-2019). We found that this year in China and Italy, there was a significantly steeper decline of flu cases than average, which correlated with an increase in positive COVID-19 case reports in those countries. These "averted" cases can be translated into a substantial decrease in morbidity and mortality. As such, we conclude that the current COVID-19 pandemic is a reminder that behavioral measures can decrease the burden of communicable respiratory infections, and these measures should be adopted to an extent during normal influenza season.

To explore whether the expression levels of viral-entry associated genes might contribute to the milder symptoms in children, we analyzed the expression of these genes in both children and adults lung tissues by single cell RNA sequencing (scRNA-seq) and immunohistochemistry (IHC). Both scRNA-seq and IHC analyses showed comparable levels of the key genes for SARS-CoV-2 entry in children and adults, including ACE2, TMPRSS2 and FURIN, suggesting that instead of lower virus intrusion rate, other factors are more likely to be the key reasons for the milder symptoms of SARS-CoV-2 infected children.

BackgroundAcute viral origins account for around 80% of respiratory illnesses globally. The influenza virus, respiratory syncytial virus, coronavirus, adenovirus, and rhinovirus are the main viruses that cause these illnesses. All ages are susceptible to severe acute respiratory infections, which have a high rate of morbidity and mortality. This study aims to determine the prevalence of viral etiology of respiratory infections among patients attending the Oromia Sentinel Surveillance Sites between July 2022 and April 2023. MethodsA facility-based cross-sectional study design was employed. We followed the WHO case definitions for each patient with a severe acute respiratory infection. The throat-swab specimens were sent to the Adama Public Health Referral and Research Capacity Building Centre after being collected in viral transport media. After that, the CDC Multiplex RT-PCR amplification procedures were applied to the specimens to detect the presence of viral RNA using CDC Real-Time reverse transcription PCR techniques. Data quality assurance was maintained. SPSS version 29 statistical software was used to compute all analyses. At 95% CI and P-value <0.05, inferential analysis was performed. ResultsThe results of this study showed that out of three hundred twenty-two throat-swab specimens collected, 100% underwent testing. Eleven (28.2%) of the thirty-nine (12.9%) who tested positive for influenza were influenza B, twenty-five (89.3%) were influenza A (H3N2), three (10.7%) were influenza A (H1N1) pdm2009. The rates of influenza positivity by age group were 58.9%, 25.6%, 5.1%, 5.1%, and 5.1% for children under five years old, 5-14 years old, 15-49 years old, 50-64 years old, and older than or equal to 65 years old. Three hundred and twenty-two (100%), twenty-two (7.3%), and eleven (3.6%) of the specimens examined for severe acute respiratory infections proved positive for the RSV and SARS-CoV-2 viruses, respectively. Furthermore, of the severe acute respiratory infection specimens that tested positive for Respiratory syncytial virus, 91% were from under five age groups. ConclusionChildren under five are at risk of co-infection with various viruses, potentially leading to epidemics and severe illnesses. A comprehensive approach to IPC measures is needed to reduce these risks.

Flaviviruses are vector-borne positive sense RNA viruses with enormous potential to cause a spectrum of severe diseases in naive populations and long-term public health impact. Several of these Flavivirus es can co-circulate; recently, Zika virus (ZIKV) is becoming increasingly prevalent in Dengue virus (DENV) endemic regions. Pre-existing immunity to one virus can modulate the response to a heterologous virus; however, the serological cross-reaction between these emerging viruses in DENV endemic region are poorly understood. In this study, we estimated the seropositivity rates of nine different Flavivirus es among residents of Manaus city in Brazil. Next, we assessed antibody cross-reactivity of DENV-positive individuals with ZIKV using hemagglutination inhibition assay (HIA), purified envelope proteins in an ELISA, and live virus neutralization test. 74.52% of participants were IgG positive (310/416) as estimated by lateral flow tests. Overall, 93.7% of participants were seropositive (419/447) for at least one DENV serotype and the DENV seropositivity ranged between 84.8% and 91.0% as determined by HIA. DENV positive individuals with high antibody titers in HIA or envelope protein domain III (EDIII)-ELISA reacted strongly with ZIKV, whereas individuals with low anti-DENV antibody titers reacted poorly towards ZIKV. Live virus neutralization test with ZIKV confirmed that dengue serogroup and ZIKV-spondweni serogroup are distant and DENV-positive individuals do not cross-neutralize ZIKV efficiently. Taken together, we observed a high prevalence of DENV in the Manaus-Amazon region and a varying degree of serological reactivity against emerging viruses. Ecological and epidemiological conditions in Manaus makes its population susceptible for further arbovirus outbreaks; hence functional vector control program and febrile-syndrome surveillance are essential to identify unforeseen epidemiological threats.

BackgroundCoronavirus disease 19 (COVID-19) has become a global unprecedented pandemic infecting more than one millon people, which is declared by WHO as a international public health emergency. Eosinopenia may predict a poor prognosis of COVID-19. However, to date, there is no detailed analysis of the clinical characteristics of COVID-19 patients with eosinopenia. Research questionThe aim of this study was to describe clinical characteristics of COVID-19 patients with eosinopenia. Study Design and MethodsThis was a multi-center retrospective study conducted in three tertiary hospitals. A total of 59 patients with COVID-19 were reviewed from January 23, 2020 to March 10, 2020. We described clincial characteristics of patients with COIVD-19 and eosinopenia phenotype. ResultsThe median age of patients with COVID-19 was 39 years old, and 32 (54,2%) were male. Patients with severe type had higher proportions of dyspnea (50%) and gastrointestinal symptoms (50%) compared with mild or moderate patients. Laboratory findings indicated that lower counts of lymphocyte and eosnophils were observed in patients with severe type. Cough, sputum, and fatigue were more common symptoms in eosinopenia patients compared with non-eosinopenia patients. High proportion of comorbidities was observed in eosinopenia patients. Laboratory findings indicated that lymphocyte counts (median: 101 cells/l) in eosinopenia patients were significantly less than those of non-eosinopenia patients (median: 167 cells/l, p<0.001). The use of corticosteroids therapy in COVID-19 patients with eosinopenia were notably higher than those in patients with non-eosinopenia (50% vs 13.8%, respectively, p=0.005). Compared with parameters in non-eosinopenia patients, eosinopenia patients were more inclined to have less lymphocyte counts (OR value 6.566, 95%CI[1.101-39.173], p=0.039). InterpretationEosinopenia are very common in COVID-19 patient, particularly in severe patients. Common symptoms included fever, cough, sputum, and fatigue are frequent in eosinopenia patients. Eosinopenia may represent a novel phenotype in COVID-19, which needs further investigation.

The innate host defence system is designed to resist pathogenic microorganism infections. Despite the compelling scientific evidence, our understanding of the full potential of the mechanism is still unclear due to the complex interactions between hosts and invaders. We previously reported latency in cat mucosal infected with low-dose cell-associated feline immunodeficiency virus (102 and 103 infected cells). Here we investigated the expression of Apolipoprotein B mRNA-editing enzyme catalytic subunit 3G (APOBEC3G or A3G) in feline cells and tissues and whether its presence antagonizes the viral pre-integration complex resulting in partial or complete FIV latency. Total RNA and protein lysates were collected from cell lines, blood, and tissue samples. Real-time RT-PCR and western blot assays were used to quantify fA3G-like protein in cats exposed to high versus low-dose cell-associated FIV. We consistently detected fA3G-like protein in mock T-cell lines (E-CD4+, MYA-1, Crandell feline kidney cells) and primary bone marrow-derived macrophages with variable expressions in feline peripheral blood mononuclear cells (PBMC). In addition, the fA3G-like protein was found to interact with FIV group-specific antigen (Gag) protein through immunoprecipitation assays. The protein expression was utterly abrogated following FIV infection. However, in lytic FIV infection (in vivo), fA3G-like protein decreased in early post-infection, whereas latently infected cats showed stable expression. These data are the first report of the fA3G-like protein expression in felines and its abrogation in lytic but not in latent FIV-infected individuals. These results might provide new insight into the role of fA3G-like protein in the host defence mechanism against retrovirus infections.

IntroductionThis paper sought to investigate the clinical characteristic differences between suspected and confirmed patients with COVID-19 from CT scan to prevent and treat this infectious disease, since the coronavirus outbreak in the world has seriously affected the quality of life. MethodsWe proposed to use a retrospective case-control study to give a comparison between suspected patients and confirmed patients in the clinical characteristics. Results(56%) patients were confirmed for COVID-19 from suspected 167 patients. We find that elder people were more likely to be infected by COVID-19. Among the confirmed 94 patients, 2 (2%) patients were admitted to an intensive care unit, and 0 (0%) patients died during the study period. We find that images of CT scan of patients with a COVID-19 are significantly different from patients without a COVID-19. ConclusionsTo our best knowledge, it is the first time to use the case-control design to study the coronavirus disease, since it is particularly appropriate for investigating infectious disease outbreaks. The clinical treatment experience in this study can supply a guideline for treating COVID-19 as the number of the infected patients is increasing in the world. Compared with other studies, we find that the mortality rate and the intensive care unit rate can be reduced if patients can be treated timely in the right identification and detection with nucleic acid testing and chest CT scan. Therefore, we recommend nucleic acid testing and chest CT scan for the clinical treatment practice from this successful clinical treatment study.

Picornaviruses represent a diverse group of plus-stranded RNA viruses, many of which have been linked to severe diseases in both humans and animals. The viral 3C protease is essential for the maturation of viral proteins and the propagation of picornaviruses and, owing to its cleavage activity against multiple host proteins, is associated with the pathogenesis of picornaviruses. The picornaviral 3C protease is an ideal drug target for inhibiting viral propagation and mitigating pathogenesis; however, methodology to evaluate and compare the activity of phylogenetically diverse proteases remains lacking. To address this, herein, we propose a novel green fluorescent protein (GFP)-based reporter optimized to visualize the enzymatic activity of picornaviral 3C proteases in cells by using the conformational change of a GFP variant induced by the 3C protease, generating fluorescence emission linked to the enzymatic activity. Upon treatment of picornaviruses with a known 3C protease inhibitor, the fluorescence decreased in a dose-dependent manner, demonstrating that the signal depended on the activity of the 3C protease. The reporter system for the 3C protease can be applied to major pathogenic human picornaviruses, such as those in the genera Enterovirus, Rhinovirus, Cosavirus, Salivirus, and Kobuvirus. Furthermore, the fluorescent signal from the reporter was confirmed in various animal- derived picornaviruses, such as those from bats, rodents, and primates. Therefore, the reporter could be widely used to analyze the activity of several 3C proteases from currently prevalent picornaviruses and those that may emerge in the future. To demonstrate the flexibility of the reporter in comparing phylogenetically different proteases, the enzymatic activity of the 3C protease derived from clinical strains of enterovirus A71 (EV-A71) was tested and compared. The results showed that the amino acid residues of the 3C protease affect its activity by utilizing the reporter system. Additionally, clinical EV- A71 strains had different effects on the activity of 3C protease against host proteins. Our findings will aid in elucidating the molecular characteristics of 3C proteases among picornaviruses and developing therapeutics to mitigate the pathogenesis of these viruses.

Research with BSL-4 viruses such as Ebola, Marburg, and Nipah presents significant challenges due to their high virulence and the stringent containment measures required. A major limitation in studying viral pathogenesis and developing therapeutic strategies is the absence of suitable animal models that accurately replicate human disease. In this context, 3D cell culture systems offer significant advantages over traditional 2D monolayer cultures, mimicking native physiological conditions including cell polarization and composition. Human airway organoids, derived from pluripotent or adult stem cells, closely replicate the structure and function of the human respiratory system, providing a relevant and accessible environment for studying viral replication and pathogenesis. In contrast to conventional cell lines, airway organoids enable investigation of virus-host interactions within a human tissue context, providing insights that are more directly translatable to human disease. In our study, we generated airway organoids from both clinical donor tissues and commercially available nasal epithelial cells and showed in comparative analyses with whole lung tissue that these organoids are comparable in terms of cell composition. Despite donor-specific variations due to genetic factors, airway organoids derived from different sources and donors exhibit a remarkably similar cellular make-up. We further demonstrated that organoids derived from nasal swabs can effectively replicate BSL-4 viruses, establishing them as a standardized 3D model for broader research applications and advancing our understanding of these pathogens, especially in the absence of reliable animal models. Author SummaryThis study establishes human airway organoids as a robust model for investigating BSL-4 pathogens, such as Ebola, Marburg, and Nipah virus. Airway organoids represent reliable systems due to their ability to replicate the complexity of human respiratory epithelia and support viral infection. These organoids exhibit high susceptibility to these viruses, allowing for subsequent analysis of infection kinetics, immune evasion, and tissue-specific tropism within a controlled environment. This platform provides a powerful tool for antiviral testing and studying virus-host interactions, thus helping bridge critical gaps in high-containment virus research.

Sobemovirus ryegrass mottle virus (RGMoV) is a single-stranded positive virus with a 30 nm viral particle size. It exhibits T=3 symmetry, with 180 coat protein (CP) subunits forming the virus structure. The RGMoV genome comprises five open reading frames, encoding P1, Px, a membrane-anchored 3C-like serine protease, a virus genome-linked protein, P16, an RNA-dependent RNA polymerase, and a coat protein. The RGMoV genome size varies, ranging from 4175 nt (MW411579.1) to 4253 nt (MW411579.1) in deposited sequences. An earlier deposited RGMoV complete genome sequence of 4212 nt length (EF091714.1) was utilized to develop an infectious complementary DNA (icDNA) construct for in vitro gRNA transcription from the T7 promoter. However, when the transcribed gRNA was introduced to oat plants, it failed to induce viral infection. This indicated the potential absence of certain sequences in either the 5 or 3 untranslated regions (UTR) or both. To resolve this, the complete sequence of the 3 UTR was determined through 3 end RACE, while the 5 UTR was identified using high-throughput sequencing (HTS) - 5 RACE-seq. Only the icDNA vector containing both newly identified UTR sequences proved infectious, resulting in classical viral infection symptoms and subsequent propagation of progeny viruses, exhibiting the ability to cause repeated infection in oat plants after at least one passage. The successful generation of the icDNA highlights the synergistic potential of utilizing both methods when one approach alone fails. Furthermore, this study demonstrates the reliability of HTS as a method for determining the complete genome sequence of viral genomes.

BackgroundHuman respiratory syncytial virus (HRSV) is one of the major cause of acute lower respiratory infection in infants, the elderly and people with low immunity worldwide. Based on antigenic and genetic variations, Human respiratory syncytial virus is divided into two subgroups (A and B). Each of the subgroups is further categorized into genotypes based on the phylogenetic analyses of the sequences of the second hypervariable region. MethodsNasopharyngeal swabs (NPSs) were collected from patients of the First Peoples Hospital in Huzhou from January 2016 to December 2019. Real-time RT-PCR (qPCR) was performed using double nucleic acid detection kit for respiratory syncytial virus (A\B) (Shenzhen shengkeyuan) with the ABI Q7 (Applied Biosystems). For genotyping, the primer set A-F/A-R was used to amplify the G protein of HRSV-A. Primer set B-F/B-R was used to amplify the G protein of HRSV-B. The phylogenetic analysis was constructed using the neighbor-joining algorithm with the Kimura two-parameter model and supported statistically by bootstrapping with 1000 replicates with MEGA software (version 7.0) with 1000 bootstrap replicates. ResultsA total of 973 nasopharyngeal swab samples were collected from January 2016 to December 2019, and 63 samples were positive for RSV nucleic acid, with the detection rate of 6.47%. Of the positive specimens, 28 were belonged to HRSV-A, and 35 were belonged to HRSV-B. Infection with RSV was found in all age groups tested, with the 0-1 year age group having the highest detection rate 15.2%. The detection rate was high from November to next March. Phylogenetic analysis clustered HRSV-A strains identified in Huzhou into ON1genotype. All 17 of the HRSV-B strains belonged to BA9 genotype. ConclusionsWe analyzed the HRSV strains circulation in Huzhou from January 2016 to December 2019 in Huzhou, China. This is the first molecular analysis on HRSV in Huzhou. We found Subgroup A and B of RSV were co-circulating and the 0-1 year age group having the highest infection rate.

Autophagy is a catabolic process used for the degradation of organelles and proteins. Macroautophagy involves the formation of autophagosomes and subsequent fusion with lysosomes to mediate cargo degradation. It also functions as a cellular defence mechanism, known as xenophagy, during infection. Previous studies show that different viruses manipulate the autophagy pathway of the host cell to assure successful replication and/or virion assembly. Vaccinia virus (VACV), the prototypic poxvirus, replicates exclusively in the cytoplasm of host cells. It is known that VACV infection causes LC3 lipidation and prevents autophagosome formation, yet the double membrane vesicles formed during autophagy do not serve as the source of the mature VACV membrane. To date the viral protein(s) causing increased LC3 lipidation have not been identified. Here we developed an image-based screening approach based on LC3 granularity to identify candidate VACV genes affecting its lipidation. We identify several candidate viral membrane proteins as effectors of LC3 lipidation, suggesting that the interplay between VACV and autophagy is more directed than previously thought.

Rabies virus (RABV), a fatal zoonotic pathogen, remains a significant public health concern, with bat-maintained lineages accounting for all currently documented cases in Brazil. Despite the availability of pharmacological prophylaxis for humans and animals, the high genetic diversity of RABV in diverse natural bat hosts and continued circulation in multiple animals pose challenges for effective surveillance. Here, we developed and validated a novel, rapidly deployable amplicon-based sequencing approach for rabies virus (RABV) genomic surveillance. This "all-in-one" protocol integrates whole RABV genome sequencing with host species identification through COI gene amplification and sequencing, addressing the challenges posed by RABVs high genetic diversity and complex transmission dynamics. We assessed the protocols effectiveness by sequencing 25 near-complete RABV genomes from host species across four distinct families (Bovidae, Equidae, Felidae, and Microchiroptera) obtained from the Rabies Control and Surveillance Program in Rio Grande do Sul State, Southern Brazil. The method achieved an average genome coverage of 91.4% at a minimum 5x read depth, with a mean depth coverage of 816x across sequenced genomes. The results demonstrated significant Bat-Clade sublineage diversity, which was classified using the MADDOG RABV lineage system. The protocol successfully identified three bat species (Tadarida brasiliensis, Desmodus rotundus, and Myotis nigricans) among the samples, highlighting its capability for precise host identification. This study presents a powerful tool for high-resolution evaluation of RABV genomic features and host identification, enabling more targeted public health interventions. This new approach has the potential to enhance RABV surveillance capabilities, contributing to more effective rabies control strategies within a One Health framework.

In 2023, three autochthonous DENV-3 cases were detected in Roraima and one imported case in Parana, fifteen years after the last DENV-3 outbreak in Brazil. Phylogenetic analyses confirmed all belonging to a new Asian lineage recently introduced in the Americas, raising concerns about future large dengue outbreaks in this region.

Chikungunya virus (CHIKV) is an enveloped RNA virus that causes Chikungunya fever in humans. It is classified into the arboviruses (arthropod-borne viruses) and is transmitted by mosquitoes. Therefore, mosquitoes can replicate many types of cells derived from mammals or insects. In this study, we tried to establish the widely useable Chikungunya virus pseudotype-system adapting various viral species, and we demonstrated the production of Chikungunya pseudotype virus baring the envelope protein from two different viral families, Coronaviridae or Rhabdoviridae i.e., severe acute respiratory syndrome coronavirus 2 spike protein (CoV-2-S) or vesicular stomatitis virus glycoprotein (VSV-G), respectively. We found that the capsid protein of Chikungunya virus is not always necessary in the formation of Chikungunya virus-based pseudotypes, but that the capsid protein increases the efficiency of expression of the sub-genomic RNA which codes the labeled genes. Our established pseudotype virus-producing system supplied a sufficient titer of virions for application to most virological experiments that showed more than 104 focus forming units (FFU)/ml. The pseudotype infections were strictly dependent on compatibility between the viral envelope protein and its receptor and there was no false-positive background infection. Our established pseudotype virus system can be used as a robust platform to study various virus infections and for screening and in-depth evaluation of neutralizing antibodies and antiviral agents.

Coronavirus 2019 infection (COVID-19) outbroke in Wuhan, Hubei and spread to all provinces in China and other countries. Shenzhen ranked the top cities outside Wuhan with reported 416 confirmed cases by February 20, 2020. Here, we analyzed the epidemiological characteristics of COVID-19 in Shenzhen and potential link to the preventive strategies for the whole city and inside hospitals. Based on the daily new cases, the epidemic of COVID-19 in Shenzhen can be classified into three phases: the slow increase phase from January 19 to January 28, the rapid increase and plateau phase from January 29 to February 5 and the decline phase since February 6. In the three phases, the number of patients from Hubei decreased, and the number of familial clustering cases increased. The newly diagnosed COVID-19 cases reached its peak around January 31, which was 7 days after the peak date of cases arrival at Shenzhen. A series of early preventive strategies were implemented since January 19, which included detection of body temperature at all entrances of main traffic and buildings, outpatients service specially for patients with fever in all main hospitals in Shenzhen. All the patients with fever were screened with nasal or throat swab PCR detection of coronavirus 2019, Chest CT and blood lymphocyte counting in order to find out early case of COVID-19. Observation wards were established in every main hospital and a designated hospital was responsible for admission and medical care of all confirmed cases. Protection procedure was established for all medical staff involved in the screening and care of suspected and confirmed cases. 14 days isolated observation of all subjects arrived at Shenzhen from Hubei was implemented in February 2. After the implementation of all these strategies and measures, the COVID-19 cases started to decline since February 6. There were almost no community transmission and nosocomial infection occurred in Shenzhen. In conclusion, in situation of major outbreak of respiratory infectious disease, such as COVID-19, in nearby province of Hubei, Shenzhen, a high population density, high proportion of external population and high mobility city, has to face the imported cases and risk of spreading the outbreak into Shenzhen city. The implementation of early preventive strategies and measures in Shenzhen were successful in early identification of COVID-19 cases and prevented major outbreak occurred in Shenzhen. Early identification of imported cases, prevention of family clustering transmission, preventive measures in the public area and very strict infection control procedure in hospital setting are crucial for the successful control of outbreak in Shenzhen.

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) is believed to have a zoonotic origin. Bats are a suspected natural host of SARS-CoV-2 because of sequence homology with other bat coronaviruses. Understanding the origin of the virus and determining species susceptibility is essential for managing the transmission potential during a pandemic. In a previous study, we established an in vitro animal model of SARS-CoV-2 susceptibility and replication in a non-permissive avian fibroblast cell line (DF1) based on expression of angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) from different animal species. In this work, we express the ACE2 of seven bat species in DF1 cells and determine their ability to support attachment and replication of the original SARS-CoV-2 Wuhan lineage virus, as well as two variants, Delta and Lambda. We demonstrate that the ACE2 receptor of all seven species: little brown bat (Myotis lucifugus), great roundleaf bat (Hipposideros armiger), Pearsons horseshoe bat (Rhinolophus pearsonii), greater horseshoe bat (Rhinolophus ferrumequinum), Brazilian free-tailed bat (Tadarida brasiliensis), Egyptian rousette (Rousettus aegyptiacus), and Chinese rufous horseshoe bat (Rhinolophus sinicus), made the DF1 cells permissible to the three isolates of SARS-CoV-2. However, the level of virus replication differed between bat species and variant tested. In addition, the Wuhan lineage SARS-CoV-2 virus replicated to higher titers (104.5-105.5 TCID50) than either variant virus (103.5-104.5 TCID50) on pass 1. Interestingly, all viruses tested grew to higher titers (approximately 106 TCID50) when cells expressed the human ACE2 gene compared to bat ACE2. This study provides a practical in vitro method for further testing of animal species for potential susceptibility to current and emerging SARS-CoV-2 viruses.

In 2023, a new yellow fever virus (YFV) lineage was introduced in Sao Paulo State, Brazil. From July 2024 to June 2025, nine Callithrix penicillata tested positive, showing low YFV viral load but characteristic organ lesions, suggesting this genus may replace Alouatta sp. as sentinel to detect YFV circulation.

SARS-CoV-2 pandemic has changed the global landscape since last two years. Against many challenges posed by the COVID-19 pandemic to the humanity, the pace of solutions created by mankind is exemplary; diagnostics, vaccines, alternate therapies, to name a few. With a rapidly changing virus strain, its early identification in the community can be a quick solution to trace the individuals and thus control its spread. This paper describes PCR based quick method for differentiation of Omicron variant of SARS-CoV-2 from other variants. Timely identification of this new variant will enable better management of pandemic control in the population. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=104 SRC="FIGDIR/small/21268053v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@7a5e9forg.highwire.dtl.DTLVardef@1da2339org.highwire.dtl.DTLVardef@3eab87org.highwire.dtl.DTLVardef@6f3258_HPS_FORMAT_FIGEXP M_FIG C_FIG