Swine flu virus shows genetic mutation
: The swine flu virus isolated from the throat swab samples of six H1N1-infected patients at the National Institute of Virology (NIV) has shown a small genetic mutation. All the six patients are from Pune. Scientists have, however, made it clear that the mutation has nothing to do with the high virus activity seen in Gujarat where 110 people have succumbed to the contagion since January till date.
"It is very important to study every mutation the swine flu virus undergoes. We have detected small mutations at two positions in the virus's genetic make up. We are closely monitoring every change. At present, there is no cause for alarm. The virus is fully susceptible to oseltamivir- which is an active ingredient in Tamiflu," D T Mourya, director, NIV told TOI on Friday.
Elaborating, senior scientist Mandeep Chadha, deputy director, NIV said, "Small mutations have been observed at two positions - D97 N and K 283 - of the amino acid in the haemagglutinin (HA) gene of the swine flu virus. Similar observations on the mutation at two positions have been made in US, Singapore and Mexico."
Genetic characterisation indicated that the viruses predominantly clustered in clade 7 (clade is a group of organisms believed to have evolved from a common ancestor), which is globally the most widely circulating pH1N1 clade. It is imperative to continue monitoring the genetic make-up of the pH1N1 viruses to understand their adaptability and evolutionary dynamics in the country, states the recently published research article of the NIV scientists.
Evidence for adaptive evolution in the HA was observed in the clade 7 isolates at the 'Ca' antigenic site that may have implications for future re-evaluation of the vaccine composition.
"The study thus warrants the need for continued surveillance and genetic characterization of whole genome sequences to detect any possible re-assortment events that might further contribute to the viral fitness of the pH1N1 viruses," the research paper stated.
NIV has characterized 31 full genomes and 94 haemagglutinin (HA) sequences of the pH1N1 viruses from various regions of India between May 2009 and October 2010.
"The 2009 influenza A(H1N1) pandemic has been characterised by mild and self-limiting disease in the overwhelming majority of cases. However, severe and fatal cases have been occurring in age groups where such clinical outcomes are very rarely seen in seasonal influenza," said paediatrician Sharad Agarkhedkar, former president of the Indian Medical Association (IMA), Pune branch.
"However, such apparently minor changes may result in drastic changes in the resulting protein molecule. For example, it may lead to drug resistance or change in virulence. Hence continuous monitoring is very important," said Agarkhedkar.
Among the newly identified mutations reported in the pandemic H1N1 virus that could alter the viral fitness, E374K in the HA was increasingly noted in 35 Indian isolates beyond September 2009 and its co-occurrence with D97N or V30A was also observed in the more recent isolates.
"It is very important to study every mutation the swine flu virus undergoes. We have detected small mutations at two positions in the virus's genetic make up. We are closely monitoring every change. At present, there is no cause for alarm. The virus is fully susceptible to oseltamivir- which is an active ingredient in Tamiflu," D T Mourya, director, NIV told TOI on Friday.
Elaborating, senior scientist Mandeep Chadha, deputy director, NIV said, "Small mutations have been observed at two positions - D97 N and K 283 - of the amino acid in the haemagglutinin (HA) gene of the swine flu virus. Similar observations on the mutation at two positions have been made in US, Singapore and Mexico."
Genetic characterisation indicated that the viruses predominantly clustered in clade 7 (clade is a group of organisms believed to have evolved from a common ancestor), which is globally the most widely circulating pH1N1 clade. It is imperative to continue monitoring the genetic make-up of the pH1N1 viruses to understand their adaptability and evolutionary dynamics in the country, states the recently published research article of the NIV scientists.
Evidence for adaptive evolution in the HA was observed in the clade 7 isolates at the 'Ca' antigenic site that may have implications for future re-evaluation of the vaccine composition.
"The study thus warrants the need for continued surveillance and genetic characterization of whole genome sequences to detect any possible re-assortment events that might further contribute to the viral fitness of the pH1N1 viruses," the research paper stated.
NIV has characterized 31 full genomes and 94 haemagglutinin (HA) sequences of the pH1N1 viruses from various regions of India between May 2009 and October 2010.
"The 2009 influenza A(H1N1) pandemic has been characterised by mild and self-limiting disease in the overwhelming majority of cases. However, severe and fatal cases have been occurring in age groups where such clinical outcomes are very rarely seen in seasonal influenza," said paediatrician Sharad Agarkhedkar, former president of the Indian Medical Association (IMA), Pune branch.
"However, such apparently minor changes may result in drastic changes in the resulting protein molecule. For example, it may lead to drug resistance or change in virulence. Hence continuous monitoring is very important," said Agarkhedkar.
Among the newly identified mutations reported in the pandemic H1N1 virus that could alter the viral fitness, E374K in the HA was increasingly noted in 35 Indian isolates beyond September 2009 and its co-occurrence with D97N or V30A was also observed in the more recent isolates.
