In the new study, a particular variant of H5N1, labeled 18.104.22.168, was observed in Egypt. There, avian flu has already killed thousands of birds and caused 173 human cases, of which 63 have been fatal as of December 10th, 2013, according to the World Health Organization. These are the highest case numbers for H5N1 outside of Asia. As in the case of Asian H5N1, experts associate most human infections in Egypt with exposure to diseased poultry, particularly at live bird markets.
In their attempts to identify the origin and spread of the virus in Egypt, researchers made use of a new software platform created by Professor Scotch. Known as ZooPhy, the program enables the phylogeographic analysis of H5N1 spread. (Maps of viral spread made with ZooPhy may be seen in the accompanying video below.)
The avian influenza virus H5N1 takes its name from two kinds of spikes adorning the viral surface, hemagglutinin (HA) and neuraminidase (NA). Influenza viruses of Type A or Type B use hemagglutinin to attach to cell surface receptors, allowing viral infection of the cell. Neuraminidase later acts to remove these receptors from infected cells, allowing newly synthesized viruses particles to escape and infect other cells.
(There are 17 different types of hemagglutinin, from H1 to H17 and nine different types of neuraminidase, from N1 to N9 among influenza A viruses. Each virus has one type of H (such as H5) and one type of N (such as N1).)
Through the analysis of 226 HA and 92 NA sequences, Scotch and his colleagues used a phylogeographic approach to trace the preponderance and transmission routes of H5N1 in Egypt. Phylogeography is a particularly fruitful approach for animal-to-human (or zoonotic) RNA viruses, due to short genomic sequences and rapid rates of evolution.
The group's findings revealed a geographic spread of the 22.214.171.124 viral form of H5N1 across Egypt's four prima
|Contact: Joseph Caspermeyer|
Arizona State University