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Genetic analysis of H3N2 influenza A viruses isolated in 2006-2007 in Nairobi, Kenya.

ABSTRACT: Minimal influenza surveillance has been carried out in sub-Saharan Africa to provide information on circulating influenza subtypes for the purpose of vaccine production and monitoring trends in virus spread and mutations.The aim of this study was to investigate a surveillance program in Kenya to isolate and characterize influenza viruses.In the 2006-2007 influenza season, nine influenza A viruses were isolated. All were of H3N2 subtype with key amino acid (aa) changes indicating that they were more closely related to recent World Health Organization recommended vaccine strains than to older vaccine strains, and mirroring the evolution of circulating influenza A globally. Hemagglutination inhibition data showed that the 2006 Kenya isolates had titers identical to the 2005-2006 H3N2 vaccine strain but two- to threefold lower titers to the 2006-2007 vaccine strain, suggesting that the isolates were antigenic variants of the 2006-2007 vaccine strains. Analysis of aa substitutions of hemagglutinin-1 (HA1) protein of the 2006 Kenyan viruses revealed unique genetic variations with several aa substitutions located at immunodominant epitopes of the HA1 protein. These mutations included the V112I change at site E, the K 173 E substitution at site D and N 278 K change at site C, mutations that may result in conformational change on the HA molecule to expose novel epitopes thus abrogating binding of pre-existing antibodies at these sites.Characterization of these important genetic variations in influenza A viruses isolated from Kenya highlights the importance of continuing surveillance and characterization of emerging influenza drift variants in sub-Saharan Africa.

SUBMITTER: Bulimo WD

PROVIDER: S-EPMC4634699 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature

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Genetic analysis of H3N2 influenza A viruses isolated in 2006-2007 in Nairobi, Kenya.

Bulimo Wallace D WD Garner Jason L JL Schnabel David C DC Bedno Sheryl A SA Njenga M Kariuki MK Ochieng Walter O WO Amukoye Evans E Magana James M JM Simwa James M JM Ofula Victor O VO Lifumo Samwel M SM Wangui Julia J Breiman Robert F RF Martin Samuel K SK

Influenza and other respiratory viruses 20080501 3

<h4>Background</h4>Minimal influenza surveillance has been carried out in sub-Saharan Africa to provide information on circulating influenza subtypes for the purpose of vaccine production and monitoring trends in virus spread and mutations.<h4>Objective</h4>The aim of this study was to investigate a surveillance program in Kenya to isolate and characterize influenza viruses.<h4>Results</h4>In the 2006-2007 influenza season, nine influenza A viruses were isolated. All were of H3N2 subtype with ke ...[more]

PMID: 19453470

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Project description:BackgroundSince the first outbreak recorded in northern areas of Pakistan in early 2006, highly pathogenic avian influenza H5N1 viruses were isolated from commercial poultry and wild/domestic birds from different areas of Pakistan up to July 2008. Different isolates of H5N1 were sequenced to explore the genetic diversity of these viruses.ResultsPhylogenetic analysis revealed close clustering and highest sequence identity in all 8 genes to HPAI H5N1 isolates belonging to unified H5 clade 2.2, sub-lineage EMA-3 recovered from Afghanistan during the same time period. Two subgroups within Pakistani H5N1 viruses, from domestic and wild birds, were observed on the basis of their sequence homology and mutations. HPAI motif, preferred receptor specificity for α-(2, 3) linkages, potential N-linked glycosylation sites and an additional glycosylation site at the globular head of HA protein of four Pakistani H5N1 isolates. While, the amino acids associated with sensitivities to various antiviral drugs (Oseltamivir, Zanamivir, Amantadine) were found conserved for the Pakistani H5N1 isolates. Conspicuously, some important mutations observed at critical positions of antigenic sites (S141P, D155S, R162I & P181S) and at receptor binding pocket (A185T, R189K & S217P) of HA-1. A high sequence similarity between Pakistani HP H5N1 and LP H9N2 viruses was also observed. Avian like host specific markers with the exception of E627K in PB2, K356R in PA, V33I in NP, I28V in M2 and L107F in NS2 proteins were also observed.ConclusionsVarious point mutations in different genes of H5 viruses from Pakistan were observed during its circulation in the field. The outbreaks started in Khyber Pakhtoon Khawa (North West) province in 2006 and spread to the Southern regions over a period of time. Though migratory birds may have a role for this continued endemicity of clade 2.2 H5N1 viruses during 2006-2008 in Pakistan, the possibility of their transmission through legal or illegal poultry trade across the borders cannot be ignored.

Dataset Information

Genetic analysis of H3N2 influenza A viruses isolated in 2006-2007 in Nairobi, Kenya.

Publications

Genetic analysis of H3N2 influenza A viruses isolated in 2006-2007 in Nairobi, Kenya.

Similar Datasets

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