3c). Following primary transcription and translation of viral proteins, importin-α proteins also mediate nuclear import of the newly synthesized NP and PB2 proteins required to sustain virus replication. Importin-α proteins have been strongly implicated in influenza A host-specific adaptation82,83.
What determines the host range of a virus?
Host range at a cellular level is determined by a combination of susceptibility, the ability of cells to allow entry of virions into the cytoplasm, and permissiveness, the capacity of cells to support cytoplasmic viral replication.
The serotype of influenza A virus is determined by the Hemagglutinin (HA) and Neuraminidase (NA) proteins present on its surface. Neuraminidase (NA) has 11 known subtypes, hence influenza virus is named as H1N1, H5N2 etc., depending on the combinations of HA and NA.
What are the proteins in influenza virus?
Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N).
What protein is involved in binding of the flu virus to host?
Abstract. Host cell attachment by influenza A viruses is mediated by the hemagglutinin glycoprotein (HA), and the recognition of specific types of sialic acid -containing glycan receptors constitutes one of the major determinants of viral host range and transmission properties.
What is the protein coat of a virus called?
The capsid surrounds the virus and is composed of a finite number of protein subunits known as capsomeres, which usually associate with, or are found close to, the virion nucleic acid.
What determines host specificity?
Conclusions. Overall, we demonstrated that the determinant of host specificity resides in the regulation of essential effector gene expression that could be under the control of a single or of very few regulatory genes.
What is the function of the hemagglutinin HA protein on the influenza flu virus?
The hemagglutinin(HA) of influenza virus is a major glycoprotein and plays a crucial role in the early stage of virus infection: HA is responsible for binding of the virus to cell surface receptors, and it mediates liberation of the viral genome into the cytoplasm through membrane fusion.
What does M2 protein do?
M2 of the influenza virus is an intriguing transmembrane protein that forms a minuscule proton channel in the viral envelope. Its recognized function is to equilibrate pH across the viral membrane during cell entry and across the trans-Golgi membrane of infected cells during viral maturation.
What are hemagglutinin proteins?
hemagglutinin, any of a group of naturally occurring glycoproteins that cause red blood cells (erythrocytes) to agglutinate, or clump together. These substances are found in plants, invertebrates, and certain microorganisms.
How many proteins does influenza A encode?
All rights reserved. With the HA and NA genes, the influenza A genome contains eight genes encoding 11 proteins. These proteins include three RNA polymerases that function together as a complex required by the virus to replicate its RNA genome.
What does hemagglutinin and neuraminidase do?
Hemagglutinin-neuraminidase (HN) protein, which is responsible for virus attachment, interacts with the fusion protein in a virus type-specific manner to induce efficient membrane fusion.
Which are the attachment sites for hemagglutinin spike proteins of influenza virus?
The viruses attach to cells within the nasal passages and throat (i.e., the respiratory tract). The influenza virus’s hemagglutinin (HA) surface proteins then bind to the sialic acid receptors on the surface of a human respiratory tract cell.
The ensuing synthesis of viral proteins is required for viral genome replication and progeny virion production. Typically, commandeering ribosomes to viral mRNAs involves subverting cellular translation factors and signalling pathways that control the host protein synthesis apparatus.
What are the accessory proteins of influenza B?
The three largest segments each encode one of the viral polymerase subunits, PB2, PB1, and PA. The second segment also encodes an accessory protein, PB1-F2, from an alternate open reading frame within the PB1 gene. PB1-F2, which is unique to influenza A viruses, localizes to mitochondria and has pro-apoptotic activity.