- Sequences of the PB2 gene from two isolates at Novosibirsk
(A/duck/Novosibirsk/56/05(H5N1) and A/grebe/Novosibirsk/29/05(H5N1)) have
been made public at GenBank. The PB2 gene sequence has been of interest
because the 16 isolates from Qinghai Lake had the E627K polymorphism which
has been linked to increased virulence in mice as well as a poor outcome
in human or tigers infected with H5N1 carrying the polymorphism.
- The E627K polymorphism had been strictly segregated by
species prior to the reported isolates from Qinghai Lake. All H5N1 isolates
from birds had an E at position 627, while all human isolates with a human
serotype (H1, H2, or H3) has a K at that position.
- Surprisingly, all 16 Qinghai Lake isolates had E627K,
which has also been isolated from mouse brains. The two sequences at GenBank
from Novosibirsk also had the E627K polymorphism.
- Also of interest were three polymorphisms shares by the
Qinghai Isolates and European swine. Surprisingly, the Novosibirsk isolates
only had the third polymorphism found in swine. The first two polymorphisms
were wild type. The relationship between these changes that were in all
16 Qinghai Lake isolates, and infections in humans is unknown. Third party
boxun reports described human H5N1 cases at Qinghai Lake, but such human
infections in Russia, Kazakhstan, and Mongolia were not reported. However,
there have been reported human cases with bird flu symptoms in Hunan as
well as newly confirmed cases in Vietnam, Thailand, and Indonesia, which
may be related to the arrival of wild birds.
- Today's announcement of H5 in wild birds in Canada is
cause for concern. The crested grebe in Russia was asymptomatic and H5
is rarely detected in Canada, so the 28 infected birds in Quebec and 5
in Manitoba is cause for concern.
- © 2005 Recombinomics. All rights reserved.