Genetic evolution of low pathogenecity H9N2 Avian influenza viruses in Tunisia: acquisition of new mutationsReportar como inadecuado




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Virology Journal

, 8:467

First Online: 12 October 2011Received: 23 August 2011Accepted: 12 October 2011

Abstract

BackgroundSince the end of 2009, H9N2 has emerged in Tunisia causing several epidemics in poultry industry resulting in major economic losses. To monitor variations of Influenza viruses during the outbreaks, Tunisian H9N2 virus isolates were identified and genetically characterized.

MethodsThe genomic RNA segments of Tunisian H9N2 strains were subjected to RT-PCR amplifications followed by sequencing analysis.

ResultsPhylogenetic analysis demonstrated that A-Ck-TUN-12-10 and A-Migratory Bird-TUN-51-10 viruses represent multiple reassortant lineages, with genes coming from Middle East strains, and share the common ancestor Qa-HK-G1-97 isolate which has contributed internal genes of H5N1 virus circulating in Asia. Some of the internal genes seemed to have undergone broad reassortments with other influenza subtypes. Deduced amino acid sequences of the hemagglutinin HA gene showed the presence of additional glycosylation site and Leu at position 234 indicating to binding preference to α 2, 6 sialic acid receptors, indicating their potential to directly infect humans. The Hemagglutinin cleavage site motif sequence is PARSSR*GLF which indicates the low pathogenicity nature of the Tunisian H9N2 strains and the potential to acquire the basic amino acids required for the highly pathogenic strains. Their neuraminidase protein NA carried substitutions in the hemadsorption HB site, similar to those of other avian H9N2 viruses from Asia, Middle Eastern and human pandemic H2N2 and H3N2 that bind to α -2, 6 -linked receptors. Two avian virus-like aa at positions 661 A and 702 K, similar to H5N1 strains, were identified in the polymerase PB2 protein. Likewise, matrix M protein carried some substitutions which are linked with increasing replication in mammals. In addition, H9N2 strain recently circulating carried new polymorphism -GSEV- PDZ ligand PL C-terminal motif in its non structural NS protein.

Two new aa substitutions I and V, that haven-t been previously reported, were identified in the polymerase and matrix proteins, respectively. Nucleoprotein and non-structural protein carried some substitutions similar to H5N1 strains.

ConclusionConsidering these new mutations, the molecular basis of tropism, host responses and enhanced virulence will be defined and studied. Otherwise, Continuous monitoring of viral genetic changes throughout the year is warranted to monitor variations of Influenza viruses in the field.

List of abbreviationsaaamino acid

AIVAvian Influenza virus

HAhemagglutinin

HBheamadsorption

HPAIVhighly pathogenic type

LPAILow pathogenic type

Mmatrix

NAneuraminidase

NPnucleoprotein

NSnon structural

PB2polymerase

PLPDZ ligand

RBSreceptor binding site

Electronic supplementary materialThe online version of this article doi:10.1186-1743-422X-8-467 contains supplementary material, which is available to authorized users.

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Autor: Wafa Tombari - Jihene Nsiri - Imen Larbi - Jean Luc Guerin - Abdeljelil Ghram

Fuente: https://link.springer.com/



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