![]() In host mucus, prevention of the aggregation of virus particles and The action of NA that hydrolyzes terminal sialic acid moiety fromĬell receptors thus leads to avoiding immobilization by sialic acid Antigenic Reassortmentįormation and release of newly formed virion is initiated by Quite important to explore evolution and emergence of influenza Hence, HA/NA balance and interplayīetween the host receptor and influenza virus surface proteins are In human viruses as an optimal balance is needed to preserve Two glycoproteins HA/NA balance is likely to persist equiponderant In spite of being in constant emergence and evolution, these Landscape of a viral protein is notably sensitive in terms of the ![]() Of NA, However, the amplitude to which emergence of one proteinĪffects that of the other one is under research. Some HA mutations were found to affect the adaptive landscape Owing to the interlinkage between these two surface proteins, Lead to possible emergence in production of more virulent strains This organized architecture helps virus to penetrate hostĭynamic alterations in the viral adaptability resulted fromĪntigenic drift and functional mutations in the surface proteins may That enables viruses to stride continuously away from their NA-rich swivel. Producing a spatial organization of binding and cleaving activities Labelling, Vahey and Fletcher (2019) revealed that HA and NA areĪsymmetrically distributed on the surface of filamentous viruses, Using super-resolution microscopy and site-specific fluorescent Human viruses discriminatorily bind to sialate attached to galactose H7N9 bind to sialic acid linked to galactose via an α2-3 bond, and The host range of infectivity is defined mainly by influenza A Sialic acids of glycoproteins on the surfaces of respiratory epithelialĬells. Influenza A viruses attach to cells through HA binding to terminal Virus entry into host cells and release from infected cells. Hence, hemagglutinin and neuraminidaseĪre two surface proteins of the influenza A virus that playįundamental intermediary roles in initiating pathogenicity during That can lead to alterations in the surface proteins of the virus, thisĬalled antigenic drift. If there are small mutations in the genes of influenza viruses Proteases into the functional/infectious HA1/HA2 form. (HA0) during viral replication and is subsequently cleaved by host The HA protein is synthesized as a single-chain precursor Species highlights a raised prospect for cross-species transmission (H1 to H16) and 9 NA (N1 to N9) subtypes have been identified in (NA), influenza A viruses are classified into subtypes. Glycoproteins, designated as hemagglutinin (HA) and neuraminidase States that quickly spread via human-to-human transmission to 30Ĭountries and more or less 208 countries reported this swine flu byĪccording to the serological reactivity of their surface Swine-origin influenza (H1N1) emerged in Mexico and the United In April 2009, a high pandemicĪlert was raised by the World Health Organization after a new Rise to its first human infection in Hong Kong and the fatality rate In 1997, H5N1, a highly pathogenic avian influenza virus, gave Multiple host organisms including humans, marine mammals, Type C infects human and swine while type A affects Of which, type B can exclusively infect only Influenza viruses are classified into threeĬategories A, B, and C. Influenza is a serious disease that causes outrageous morbidityĪnd mortality in every year with its great impact on either extreme Keywords: Influenza, Antigenic drift, Antigenic reassortment, Vaccine Introduction Highlights the dynamic alterations in the viral adaptability resulted from antigenic drift and reassortment that enable flu virus to escape recognitionīy the host immune system and neutralization by antibodies produced in preceding infections or vaccinations. Received: FebruPublished: March 09, 2020įrequent pandemic alerts were raised by the World Health Organization in response to newly emerging influenza strains. *Corresponding author: Mohammed Helmy Faris Shalayel, Department of Pharmacology Practice, University of Hafr Al-Batin, Saudi
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