#4771
Once again we’ve a story out of India claiming that the novel H1N1 `swine flu’ virus has `mutated’, but as in earlier media reports, we’re given very little solid information to go on.
First the article from the Hindustan Times, then a bit of discussion.
H1N1 virus has mutated
Mumbai: , June 24, 2010
Neha Bhayana , Hindustan TimesThe H1N1 virus has undergone a slight genetic mutation and its effect on patients has also changed. But patients are still responding to anti-viral drug Tamiflu.
“Unlike last year, swine flu patients don’t have high fever these days. Severe sore throat and backache are the most prominent symptoms now,” said Dr G.T. Ambe, Brihanmumbai Municipal Corporation’s executive health officer.
He added that Tamiflu and the vaccine are still “very effective.”
The state Directorate of Health Services had called for a meeting of experts and officials involved in tackling swine flu on Wednesday.
Dr A.C. Mishra, director of the National Institute of Virology, who attended the meeting in Mumbai, shared insights about the change in antigenicity of the virus (ability to cause production of antibodies), according to sources.
Infectious disease specialist Dr Om Srivastav has also observed changes in the clinical manifestation of swine flu. “Fever is not a predominant feature anymore,” he said.
“There is a small change in the virus. But this is not surprising. We expect it to change further,” said Dr Srivastav, who is part of the state government’s H1N1 advisory committee.
Although the word `mutation’ has an ominous connotation, changes in the influenza virus happen often and only rarely result in a more aggressive or dangerous flu strain.
Most of these mutations result in evolutionary dead ends; flawed viruses unable to compete against the existing strain.
In order for a mutation to become a pathogenic `player’, it has to be biologically fit, and capable of replicating reliably and efficiently.
And even when that happens, the end result isn’t necessarily bad. A virus can certainly mutate into a less virulent strain.
This isn’t the first media story about suspected mutations in the H1N1 virus to come out of India since the pandemic started.
Last March (see PB2 Mutation Detected In India) there was a brief flurry of reports about the detection of an (unspecified) change in the PB2 segment of the virus.
It was reported that this mutation had little clinical significance.
Although details were not provided, this change is thought to be similar to that which Dutch scientists isolated last September; the E627K mutation (see ProMed Mail INFLUENZA PANDEMIC (H1N1) 2009 (58): THE NETHERLANDS, PB2 MUTATION).
The E627K mutation in novel H1N1 was widely expected to expedite viral replication in humans. The fact that it apparently doesn’t was of considerable surprise to scientists around the world.
And last September The Hindu printed this somewhat hyperbolic report:
Tuesday, Sep 15, 2009
HYDERABAD: The A(H1N1) virus is showing signs of getting ‘mutated’ into a more virulent form.
Clinical observation of experts in the State capital indicate that the genetic make up of A(H1N1) virus has ‘changed’ and is now more ‘potent’ after coming into contact with the local existing viral forms.
Inferring a `mutation’ based on a change in clinical presentation is an `iffy’ proposition. And despite the warnings of a `more virulent’ result, we’ve seen little evidence to support that prediction.
Small, often incremental changes to the H1N1 virus are to be expected. After all, that’s what influenza viruses do.
They mutate. They evolve.
The significance of this most recent report is difficult to gauge, given the lack of specifics provided.
More information regarding the location and type of mutation and the transmissibility (and incidence) of this `mutated virus’ would be helpful.
For now, I consider this report interesting, but not terribly illuminating.
