A unique influenza A (H5N1) virus causing a focal poultry outbreak in 2007 in Manipur, India.
BACKGROUND
A focal H5N1 outbreak in poultry was reported from Manipur, a north-eastern state, of India, in 2007. The aim of this study was to genetically characterize the Manipur isolate to understand the relationship with other H5N1 isolates and to trace the possible source of introduction of the virus into the country.


RESULTS
Characterization of the complete genome revealed that the virus belonged to clade 2.2. It was distinctly different from viruses of the three EMA sublineages 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.


CONCLUSIONS
Considering that all eight genes of the earlier Indian isolates belonged to the EMA3 sublineage and similar strains have not been reported from neighbouring countries of the subcontinent, it appears that the virus may have been introduced independently.
Mishra
Akhilesh C
AC
Microbial Containment Complex, National Institute of Virology, Pashan, Pune 411021, Maharashtra, India. acm1750@rediffmail.com
Cherian
Sarah S
SS
Chakrabarti
Alok K
AK
Pawar
Shailesh D
SD
Jadhav
Santosh M
SM
Pal
Biswajoy
B
Raut
Satish
S
Koratkar
Santosh
S
Kode
Sadhana S
SS
D025041:Animal Migration; D000818:Animals; D004196:Disease Outbreaks; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D007194:India / Q000453:epidemiology; D053124:Influenza A Virus, H5N1 Subtype / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D005585:Influenza in Birds / Q000453:epidemiology* / Q000821:virology; D010802:Phylogeny; D011200:Poultry; D011201:Poultry Diseases / Q000453:epidemiology* / Q000821:virology; D017422:Sequence Analysis, DNA
D019267:Hemagglutinin Glycoproteins, Influenza Virus