Molecular epidemiology of influenza A(H1N1)pdm09 viruses from Pakistan in 2009-2010.
BACKGROUND
In early 2009, a novel influenza A(H1N1) virus that emerged in Mexico and United States rapidly disseminated worldwide. The spread of this virus caused considerable morbidity with over 18000 recorded deaths. The new virus was found to be a reassortant containing gene segments from human, avian and swine influenza viruses.


RESULTS
The first case of human infection with A(H1N1)pdm09 in Pakistan was detected on 18(th) June 2009. Since then, 262 laboratory-confirmed cases have been detected during various outbreaks with 29 deaths (as of 31(st) August 2010). The peak of the epidemic was observed in December with over 51% of total respiratory cases positive for influenza. Representative isolates from Pakistan viruses were sequenced and analyzed antigenically. Sequence analysis of genes coding for surface glycoproteins HA and NA showed high degree of high levels of sequence identity with corresponding genes of regional viruses circulating South East Asia. All tested viruses were sensitive to Oseltamivir in the Neuraminidase Inhibition assays.


CONCLUSIONS
Influenza A(H1N1)pdm09 viruses from Pakistan form a homogenous group of viruses. Their HA genes belong to clade 7 and show antigenic profile similar to the vaccine strain A/California/07/2009. These isolates do not show any amino acid changes indicative of high pathogenicity and virulence. It is imperative to continue monitoring of these viruses for identification of potential variants of high virulence or drug resistance.
Department of Virology, Public Health Laboratories Division, National Institute of Health, Chak Shahzad, Islamabad, Pakistan.
Uzma
U
Bashir Aamir
Nazish
N
Badar
Muhammad Rashid
MR
Mehmood
Nadia
N
Nisar
Rana Muhammad
RM
Suleman
Shehzad
S
Shaukat
Salman
S
Sharif
Jaleel
J
Kamran
Syed Sohail Zahoor
SS
Zaidi
Birjees Mazher
BM
Kazi
Larisa
L
Gubareva
Xiyan
X
Xu
Rebecca
R
Garten
Alexander
A
Klimov
D006031:Glycosylation; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000378:metabolism; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D017720:Molecular Epidemiology; D009439:Neuraminidase / Q000378:metabolism; D010154:Pakistan / Q000453:epidemiology; D010802:Phylogeny
D019267:Hemagglutinin Glycoproteins, Influenza Virus; D009439:Neuraminidase