Does The Ad-36 Virus Cause Obesity?
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epidemic these days. Could a virus be behind it?
Scientists have presented a new study showing infection with the
adenovirus-36 (Ad-36) virus, long recognized as a cause of respiratory
and eye infections in humans, may be a contributing factor.
Their laboratory experiments they showed that infection with Ad-36
transforms adult stem cells obtained from fat tissue into fat cells.
Stem cells not exposed to the virus, in contrast, were unchanged.
They obtained adult stem cells from fatty tissue from a broad cross-
section of patients who had undergone liposuction. Half of the stem
cells were exposed to Ad-36 and the other half were not exposed to the
virus.
After about a week of growth in tissue culture, most of the virus-
infected adult stem cells developed into fat cells, whereas the non-
infected stem cells did not, the researchers say.
The research group recently identified a gene in the Ad-36 virus that
appears to be involved in causing fat accumulation observed in
infected animals. That gene, called E4Orfl, is now emerging as a
promising target for future human therapies, such as vaccines and anti-
viral medicines, aimed at preventing or inhibiting the obesity virus,
she says.
The exact mechanism by which the virus might cause obesity in people
is currently unknown, says Magdalena Pasarica, M.D., Ph.D., of the
Pennington Biomedical Research Center, a campus of the Louisiana State
University system, who does not rule out the possibility that other
human viruses may also contribute to obesity.
Researchers also do not know how long the virus remains in the body of
obese individuals nor how long its fat-enhancing effect lasts once the
virus is gone. However, Pasarica notes a recent study demonstrated
that animals that developed the virus remained obese up to six months
after their infection was gone. More studies are needed, especially in
humans, she adds.
“We’re not saying that a virus is the only cause of obesity, but this
study provides stronger evidence that some obesity cases may involve
viral infections,” says Pasarica. “Not all infected people will
develop obesity,” she notes. “We would ultimately like to identify the
underlying factors that predispose some obese people to develop this
virus and eventually find a way to treat it.”
Pasarica was part of the original research group which demonstrated
that the Ad-36 virus was capable of causing animals infected with the
virus to accumulate fat. Led by Nikhil Dhurandhar, Ph.D., now an
associate professor at Pennington Biomedical Research Center, the
group also conducted a noted epidemiologic study — the first to
associate a virus with human obesity — showing 30 percent of obese
people were infected with the Ad-36 virus in comparison to 11 percent
of lean individuals. But evidence that the virus could actually cause
fat levels to increase in human cells was lacking until now, Pasarica
says.
Pasarica and her associates are now in the process of trying to
identify the factors that predispose some people with the virus to
develop obesity while others do not, but results of this investigation
are not yet available, they say.
Source: American Chemical Society, BIOHW 003, presented at 10:15 a.m.,
Monday, Aug. 20, at the Boston Convention & Exhibition Center, Room
203, during the symposium, “Genomics of Obesity.”
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