Date: 8 Jan 2001 12:02:57
From: M. Cosgriff <mcosgriff@hotmail.com>
Source: South China Morning Post, Mon, 8 Jan 2001 2:01 PM SGT [edited]
<http://asia.dailynews.yahoo.com/headlines/health/article.html?s=asia/headlines/010108/health/healthanswers/HK-Devised_Bird_Flu_Test_Adopted_Worldwide.html>
Avian Influenza Virus Diagnostic Kits Adopted Worldwide
-------------------------------------------------------
HONG KONG: New testing kits for [avian influenza viruses] are being adopted
worldwide [as a result of the] discovery by Hong Kong virologists that the
lethal [H5N1 avian influenza virus] of 1997 was the product of
gene-swapping [genome sub-unit reassortment] between 3 avian influenza
viruses found in quail and geese.
These findings have led the World Health Organization (WHO) to develop
additional diagnostic kits for 3 [influenza virus hemagglutinin] genes -
H5, H9, and H6 - which are now being used internationally to monitor new
isolates. Professor Kennedy Shortridge of the Department of Microbiology of
the University of Hong Kong said it was a pioneering step forward as "World
health authorities would have a better chance of alerting people globally
[to emerging disease]."
The team found that an early form of H5N1 influenza virus from geese mixed
[had exchanged genes] with H9N2 and H6N1 viruses in quail and poultry fowl
to create the deadly H5N1 influenza virus of 1997. This H5N1 virus was
amplified to a high level in chickens, spreading throughout their organs.
Contact with contaminated chicken wastes or organs sold in the markets
subsequently passed the virus to humans.
--
ProMED-mail
<promed@promedmail.org>
[In 1997, 18 cases of influenza ("bird flu") in the Hong Kong Special
Administrative Region (SAR) caused by a novel H5N1 (chicken) virus resulted
in the deaths of 6 individuals and raised the specter of a potentially
devastating influenza pandemic. Previously it had been believed that the
introduction of novel avian influenza virus genes into human influenza
viruses (and the generation of new pandemic strains by sub-unit
reassortment) required co-infection of an intermediate host (the pig).
Slaughter of the poultry in the live bird markets of the Hong Kong SAR
removed the source of infection and no further human cases of H5N1
infection have occurred.
In March 1999, however, a new pandemic threat appeared when influenza A
H9N2 viruses infected 2 children in Hong Kong. These 2 virus isolates are
similar to an H9N2 virus isolated from a quail in Hong Kong in late 1997.
Although differing in their surface hemagglutinin and neuraminidase
components, a notable feature of these H9N2 viruses is that the 6 genes
encoding the internal components of the virus are similar to those of the
1997 H5N1 human and avian isolates.
This common feature emphasizes the apparent propensity of avian viruses
with this genetic complement to infect humans and highlights the potential
for the emergence of a novel human pathogen. This is illustrated through
the H9N2 virus, which appears to have provided the 'replicating' genes for
the H5N1 virus and which has since been isolated in the SAR from poultry,
pigs and humans, highlighting its propensity for inter-species transmission.
These events in the Hong Kong SAR have confirmed the role of avian hosts as
a source of pandemic human influenza viruses and offer the prospect of
improved forecasting of human pandemics in the future. These new reagents
will facilitate surveillance. - Mod.CP]
.
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