Nov 15 PLoS Pathogens
19 November 2012
Highly pathogenic avian H5N1 influenza viruses are now enzootic in parts of Southeast Asia and the Middle East.
Since lack of the HA154–156 glycosylation site appears to be critical for H5 virus transmission in mammals, a group of researchers inspected avian H5N1 viruses from Egypt for this feature. Closer inspection of 2009–2011 H5N1 viruses from Egypt revealed that >70% of Egyptian isolates lack the HA154–156 glycosylation site. The H5N1 viruses currently circulating in Egypt are descendants of the so-called Qinghai Lake viruses that killed wild.
All 46 H5N1 viruses isolated in 2009–2011 from infected individuals in Egypt lacked the HA154–156 glycosylation site, while 28% of H5N1 viruses circulating in avian species in Egypt in 2009–2011 possessed this site. Phylogenetic analysis further suggested that mutations resulting in loss of the glycosylation site occurred in birds and that these variants subsequently transmitted to humans. In addition, the researchers say the mutation PB2-627K, which is known to be involved in mammalian adaptation of avian flu viruses, is found in most H5N1 isolates from Egypt.