CDC rejects report of mutant H1N1 strain in Brazil

Jun 17, 2009 (CIDRAP News) – The Centers for Disease Control and Prevention (CDC) and other experts have rejected a report that a new strain of the novel H1N1 influenza virus has been identified in a Brazilian patient.

Scientists at Adolfo Lutz Bacteriological Institute in Sao Paolo said they found the new strain in a local patient who has recovered, according to a Medical News Today (MNT) report, which was based on information from the institute and Agence France-Presse.

The story said the scientists found "a number of discrete alterations in nucleotide and amino acid sequences" in the isolate's hemagglutinin (HA) gene. They also analyzed the matrix-protein (MP) gene and found no changes.

But CDC spokesman Joe Quimby in Atlanta discounted the report that the isolate is a new strain. "Our scientists have no knowledge of a new strain of novel A H1N1 influenza," he said.

"It's the same strain, it's not a new strain," Quimby added.

The Brazilian researchers labeled the isolate A/Sao/Paolo/1454/H1N1. They deposited the nucleotide sequences for the HA and MP genes in GenBank under accession numbers GQ247724 and GQ250156, the MNT report said.

Vincent Racaniello, PhD, a Columbia University virologist who writes Virology Blog, also dismissed the claim of a new strain.

"Comparison of the amino acid sequence of the HA protein of A/Sao Paulo/1454/H1N1 with those of other isolates of the current pandemic strain reveals no alterations in the HA protein which would allow the virus to infect new hosts," Racaniello wrote in his blog. "The HA protein of this virus and many other 2009 H1N1 isolates are identical. The few amino acid differences with other 2009 H1N1 isolates are in areas that would not be expected to influence antigenicity or host range."

The MNT report said the virus came from a 26-year-old Sao Paolo man who fell ill shortly after returning from a trip to Mexico. He was hospitalized on Apr 24 and later recovered.

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