Chinese researchers have discovered that the H5N1 strain of the
bird flu virus can pass through the placenta of pregnant women to
the unborn fetus and can infect organs other than the lungs in
adults. The findings were published in the medical journal
Lancet last month.
Professor Gu Jiang and colleagues of Peking University in
Beijing studied post-mortem tissues of one man and one pregnant
woman who were confirmed to have been infected by H5N1 virus when
they were still alive.
They also tested the fetus of the dead woman. They investigated
how the H5N1 virus, an emerging infectious disease that causes
respiratory symptoms and a high fatality rate, affects different
organs in the body.
"The transmission of the virus from mother to fetus has been
established by our study. This is the first established report of
human to human transmission as the fetus is a different individual
from the mother," says Gu.
Little damage was found in the fetus examined by the
researchers. However, any long-term problems or permanent damage to
the fetus are not known at this time, according to Gu.
"The speculation about the fate of the fetus if the mother
survived is interesting. With the development of antibodies in the
mother and their transplacental crossing into the fetus,
pathological lesions in the fetus may result," says Dr Wai Fu Ng of
the Department of Pathology at Yan Chai Hospital in Hong Kong.
The major damage of H5N1 infection is still in the lungs as most
patients died of respiratory failure, says Gu. However, so far,
little is known about the specific effects in organs and cells
targeted by the virus, which is an important question Gu and his
colleagues tried to answer in their studies.
The researchers detected viral genetic material and antigens in
the lungs, certain cells in the trachea, the T cells of the lymph
node, and neurons in the brain. Viral genetic material was also
detected in the intestinal mucosa, but no H5N1 viral antigens were
found there.
"Our next goal in research is to ascertain the organs and cell
types that can be infected by this new virus. In particular, we are
not sure if bone marrow, thymus, and a number of other immune
organs are infected," says Gu.
A major obstacle for their studies should be a lack of the
tissue samples available for molecular investigation.
Up to now, owing to the difficulties to obtain complete autopsy
of bird flu victims, only eight autopsies have been done worldwide
and some of them were only partial autopsies, according to Gu. In
particular, most of the studies did not perform molecular technique
on the samples.
Funding is urgently needed for this and other studies on bird
flu topic, according to Gu.
"Our group at Peking University have obtained many very
important results in the research of bird flu and SARS with very
limited funding. Our results have been published in a number of
important international journals that has established China's
strong position in the field of pathology and pathogenesis of
research of newly emerged infectious diseases," he says.
(China Daily October 10, 2007)
