First HIV hybrid formed in a human revealed

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http://www.newscientist.com/news/news.jsp?id=ns99993941

 

 

First HIV hybrid formed in a human revealed

 

 

The first case of two strains of HIV combining to form a new hybrid virus in a

human has been revealed by researchers.

 

More than one type of the deadly virus can infect a person at the same time - a

state called " superinfection " . Scientists have long suspected that different

strains could combine to produce a hybrid - but this had never been demonstrated

before.

 

Now scientists have shown that two major subtypes of HIV-1 swapped genes with

each other to form an entirely new virus in a female patient. Furthermore, the

hybrid took over from the original infections to become the dominant virus in

the woman's body. This caused her condition, which had been relatively stable,

to rapidly deteriorate.

 

As well as worsening the outlook for individual patients, this ability of HIV

strains to recombine could pose a crucial stumbling block in the hunt for an

AIDS vaccine. " Recombination resulting from superinfection with diverse strains

may pose problems for eliciting the broad immune responses necessary for an

effective vaccine, " said Harold Burger, of the Wadsworth Center in Albany, New

York, who led the research.

 

 

Sex workers

 

 

" The issue is can you get a vaccine that will cover all subtypes? " agrees Anton

Pozniak, an AIDS specialist at Chelsea and Westminster Hospital in London, UK.

He says even a vaccine that covers all existing subtypes could then be defeated

by a new hybrid.

 

 

 

 

 

 

 

 

 

 

 

 

 

Burger and colleagues examined the virus found in a woman patient taking part in

an ongoing study of Kenyan prostitutes - the Nairobi's Punwami Sex Workers

Cohort. She had first been tested in 1986 and was found to be infected only with

HIV-1 subtype A. Despite continuing exposure to the virus through her work as a

prostitute she remained relatively healthy.

 

However, she was suddenly struck by an acute febrile illness in April 1992. Her

CD4 white blood cell count plummeted by more than 80 per cent and the amount of

virus in her blood simultaneously rose.

 

When genetic material from the HIV in the woman's blood was analysed again in

1995 and 1997, the dominant hybrid was one that contained DNA from both type A

and type C was discovered. The hybrid took most of its genetic material from

subtype A, but sections coding for the virus's outer coat originally belonged to

subtype C.

 

The new work was presented at an International AIDS Society conference in Paris

on Monday.

 

Shaoni Bhattacharya

 

 

 

 

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