Actin cytoskeleton dynamics affect replication of Human Metapneumovirus

Human Metapneumovirus (hMPV) is responsible for viral respiratory infection with clinical and epidemiological relevance in pediatric, immunocompromised, and elderly populations. Little is known about hMPV in vitro replication processes and their relationship with cellular structures such as the cytoskeleton. Our goal was to evaluate the role of the actin cytoskeleton in hMPV replication at different stages of viral growth. hMPV was isolated in Vero cells from a clinical sample and identified as A2 genotype. The cytopathic effect was detected by the appearance of cell rounding and refractory cell clusters. The growth curve showed that viral replication maximum level was between 48 and 72 hpi. The highest percentage of infected cells and intracellular hMPV-protein were detected at the early stages of the replication cycle. Disruption of actin microfilaments with Cytochalasin D during the early events provoked an increase in both intracellular and extracellular viruses. We demonstrate that the early phase of the hMPV curve is crucial for viral replication; and the disruption of microfilaments during this time increments both viral protein expression and release of viruses to the extracellular space. This study contributes to elucidate wild-type hMPV growth kinetics, providing new insights on the actin cytoskeleton role in viral replication mechanisms.