ARS | Publication request: VIRULENCE FACTORS ASSOCIATED WITH THE HEMAGGLUTININ (HA) OF AVIAN INFLUENZA VIRUSES

Submitted to: La Sociedad Venzolana De Especialistas En Aves
Publication Type: Abstract Only
Publication Acceptance Date: November 1, 1999
Publication Date: N/A

Technical Abstract: Analysis of the structure of the avian influenza (AI) virus hemagglutinin (HA) gene and protein has yielded a wealth of information on the virulence mechanisms of influenza viruses. The AI hemagglutinin appears to be unique in its capacity to accept basic amino acids at its' proteolytic cleavage site (PCS). The association of multiple basic (MB) amino acids, tissue spread and virulence by AI strains first proposed by Klenk, Rott, Orlich and others in the late 1970's has held fast for over two decades now. While other structural characteristics and other genes can certainly influence virulence, the presence of the MB amino acids at the PCS has provided a hallmark structural feature which justifies continuing sequence analysis of emerging field isolates of AI strains. In addition to this structural feature, the distal tip of the HA is prone to appearance and disappearance of glycosylation sites, some of which have been associated with virulence. The recent outbreaks of highly pathogenic AI in Mexico, Australia, Hong Kong & in the ongoing outbreak of mildly pathogenic H7 avian influenza in the northeast United States have all provided new and useful information regarding the role of HA RNA and protein structure in both virulence & host adaptation. The structure of the avian influenza hemagglutinin is a continually changing landscape and following and characterizing these changes remains a challenge.