ARS | Publication request: Phylogenetics and pathogenesis of early avian influenza viruses (H5N2), Nigeria

Submitted to: Emerging Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2008
Publication Date: November 25, 2008
Citation: Aiki-Raji, C.O., Aguilar, P.V., Kwon, Y., Goetz, S.K., Suarez, D.L., Jethra, A.I., Nash, O., Adeyefa, C.O., Adu, F.D., Swayne, D.E., Basler, C.F. 2008. Phylogenetics and pathogenesis of early avian influenza viruses (H5N2), Nigeria. Emerging Infectious Diseases. 14(11):1753-1755.

Interpretive Summary: Since 1996, H5N1 high pathogenicity avian influenza (HPAI) outbreaks have occurred across Asia with later spread to Europe, Middle East and Africa. The first cases in Nigeria were reported during February 2006. This study describes the results of diagnostic investigations for HPAI viruses from sick and dead birds in the vicinity of Ibadan, Nigeria. These investigations yielded both HPAI and Newcastle disease viruses as etiologies of the poultry deaths. The HPAI viruses were of the H5N1 subtype and, through molecular sequencing, the hemagglutinin gene was determined to belong to Offlu subclades 2.2.2 and 2.2.3. (European-Middle Eastern-African clade 1). These findings indicate that H5N1 HPAI is not the only etiology that can cause high poultry losses in Nigeria.

Technical Abstract: Prior to the first officially recognized outbreaks of highly pathogenic avian influenza (HPAI) in poultry in Nigeria, in February 2006, an effort based at the poultry diagnostic clinic of the University of Ibadan Veterinary Teaching Hospital, was underway to isolate avian influenza viruses from sick and dead birds in the vicinity of Ibadan, Nigeria. Isolates obtained around the time of the first documented outbreaks yielded three H5N1 HPAI. Complete nucleotide sequence and phylogenetic analysis of the 8 genes shows that these viruses possess within their HA genes multibasic cleavage sites and belong to the Offlu subclades 2.2.2 and 2.2.3 (European-Middle Eastern-African clade 1) H5N1 viruses. Intravenous and intranasal pathogenicity tests in chickens provide the first careful characterization of the avian pathogenesis of African H5N1 HPAI viruses.