Unity in Diversity

Abstract

The Paramyxoviridae family includes many viruses that are pathogenic in humans, including parainfluenza viruses, measles virus, respiratory syncytial virus and the emerging zoonotic Henipaviruses. No effective treatments are currently available for these viruses, and there is a need for efficient antiviral therapies. Paramyxoviruses enter the target cell by binding to a cell surface receptor and then fusing the viral envelope with the target cell membrane, allowing the release of the viral genome into the cytoplasm. Blockage of these crucial steps prevents infection and disease. Binding and fusion are driven by two virus encoded glycoproteins, the receptor-binding protein and the fusion protein, that together form the viral “fusion machinery”. The development of efficient antiviral drugs requires a deeper understanding of the mechanism of action of the Paramyxoviridae fusion machinery, which is still controversial. Here we review recent structural and functional data on these proteins and the current understanding of the mechanism of the paramyxovirus cell entry process.

Sequence analysis of malacoherpesvirus proteins: Pan-herpesvirus capsid module and replication enzymes with an ancient connection to “Megavirales”

“…Their distant homologs include spike proteins of positive-strand RNA toroviruses and coronaviruses, as well as baculovirus F proteins (see full list of matches in Additional File 4). All these genes encode virus membrane envelope proteins that facilitate virus contact with the host receptor, virus-cell membrane fusion and virus entry into the cell (Belouzard et al, 2012;Baquero et al, 2015;Palgen et al, 2015). More distant relationships (Additional File 4) link a sub-region within these proteins to the envelope proteins of the Ty3-copia-class retrotransposons in insects (virus family Metaviridae), as well as their domesticated homologs of those proteins, such as the Iris gene product in Drosophila (Malik and Henikoff, 2005).…”

Viral Entry Properties Required for Fitness in Humans Are Lost through Rapid Genomic Change during Viral Isolation

“…Two surface glycoproteins of HPIV-3, the hemagglutinin-neuraminidase (HN) and fusion (F) proteins, work in concert to mediate fusion into the target host cell during infection. HN is a tetramer that carries out several functions in addition to serving as the receptor binding protein for the virus by binding to sialic acids ( 8 ). When HN is bound to a receptor, it activates F to a fusion ready state.…”

Respiratory Syncytial Virus and Cellular Stress Responses: Impact on Replication and Physiopathology

“…Members of the Paramyxoviridae family include several etiological agents associated with a high burden of morbidity and mortality in humans. Amongst the Paramyxovirinae subfamily are the parainfluenza viruses (PIVs), measles virus (MV), mumps virus (MuV), Nipah virus (NiV) and Hendra virus (HeV), while the Pneumovirinae subfamily includes respiratory syncytial virus (RSV) and metapneumovirus (MPV) [ 1 , 2 ]. Human RSV is a major cause of acute lower respiratory tract infection in infants, children and elderly, but also all-aged adults with a compromised immune system or cardiopulmonary diseases.…”