14.12.2012

Younan et al (2012) Emerging Infectious Diseases

An analysis of H5N1 avian influenza strains isolated from Egyptian patients from 2007 through 2011 found little evidence of reassortment but substantial antigenic drift, according to a report in Emerging Infectious Diseases. All analyzed viruses evolved from the lineage of subtype H5N1 viruses introduced into Egypt in 2006; the US and Egyptian investigators found minimal evidence of reassortment and no exotic introductions. The hemagglutinin genes of the viruses from 2011 formed a monophyletic group within clade 2.2.1 that also included human viruses from 2009 and 2010 and contemporary viruses from poultry; this finding is consistent with zoonotic transmission. Although molecular markers suggestive of decreased susceptibility to antiviral drugs were detected sporadically in the neuraminidase and matrix 2 proteins, functional neuraminidase inhibition assays did not identify resistant viruses. No other mutations suggesting a change in the threat to public health were detected in the viral proteomes. However, a comparison of representative subtype H5N1 viruses from 2011 with older subtype H5N1 viruses from Egypt revealed substantial antigenic drift.