Bird Flu Virus in Manipur in 2007 was Unique

INDIA - Study of the H5N1 virus causing the outbreak of highly pathogenic avian influenza (HPAI) in Manipur in 2007 suggests that the virus originated in Russia, China or Mongolia, and may have been brought by migrating wild birds.

24 February 2009

3 minute read

Asia

A focal H5N1 outbreak in poultry was reported from Manipur, a north-eastern state of India, in 2007. 7thspace reports that the aim of the study was to genetically characterize the Manipur virus isolate to understand the relationship with other H5N1 isolates and to trace the possible source of introduction of the virus into the country.

Characterisation of the complete genome revealed that the virus belonged to clade 2.2.

It was distinctly different from viruses of the three EMA sub-lineages of clade 2.2 but related to isolates from wild migratory waterfowl from Russia, China and Mongolia. The HA gene, had the cleavage site GERRRRKR, earlier reported in whooper swan isolates from Mongolia in 2005.

A stop codon at position 29 in the PB1-F2 protein could have implications on the replication efficiency. The acquisition of polymorphisms as seen in recent isolates of 2005-07 from distinct geographical regions suggests the possibility of transportation of H5N1 viruses through migratory birds.

The authors concluded that considering that all eight genes of the earlier Indian isolates belonged to the EMA3 sub-lineage and similar strains have not been reported from neighbouring countries of the sub-continent, it appears that the virus may have been introduced independently.

Reference

Mishra A.C., S.S. Cherian, A.K. Chakrabarti, S.D. Pawar, S.M. Jadhav, B. Pal, S. Raut, S. Koratkar and S.S. Kode. 2009. A unique influenza A (H5N1) virus causing a focal poultry outbreak in 2007 in Manipur, India. Virology Journal, 6: 26.