Actin cytoskeleton dynamics affect replication of Human Metapneumovirus

Abstract

Human metapneumovirus (hMPV) is a virus responsible for acute respiratory infection in humans with clinical and epidemiological relevance in pediatric, immunocompromised, and elderly populations. Little is known about hMPV in vitro replication biological processes and their relationship with cellular structures such as the cytoskeleton. Our goal was to evaluate the viral replication curve in order to study the role of the actin cytoskeleton in hMPV replication at different stages of viral growth. Human metapneumovirus was isolated in a Vero cell line 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 h.p.i. The highest percentage of infected cells and intracellular hMPV-protein were detected at the early stages of the replication cycle (8 h.p.i). Disruption of actin microfilaments with cytochalasin D (CytD) during the early events of infection provoked an increase in both intracellular and extracellular viruses. We demonstrate that the early phase of the hMPV curve is crucial for viral replication. We also show that disruption of actin filaments during this time increments both viral protein expression in the cytoplasm and the 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. In addition, it points out putative targets to develop new antiviral treatments.