HIV evolv­ing ‘into milder form’

Lesotho Times - - Health -

LONDON — HIV is evolv­ing to be­come less deadly and less in­fec­tious, ac­cord­ing to a ma­jor sci­en­tific study.

The team at the Univer­sity of Ox­ford shows the virus is be­ing “wa­tered down” as it adapts to our im­mune sys­tems.

It said it was tak­ing longer for HIV in­fec­tion to cause Aids and that the changes in the virus may help ef­forts to con­tain the pan­demic.

Some vi­rol­o­gists sug­gest the virus may even­tu­ally be­come “almost harm­less” as it con­tin­ues to evolve.

More than 35 mil­lion peo­ple around the world are in­fected with HIV and inside their bod­ies a dev­as­tat­ing bat­tle takes place be­tween the im­mune sys­tem and the virus.

HIV is a master of dis­guise. It rapidly and ef­fort­lessly mu­tates to evade and adapt to the im­mune sys­tem.

How­ever, ev­ery so of­ten HIV in­fects some­one with a par­tic­u­larly ef­fec­tive im­mune sys­tem.

“[Then] the virus is trapped be­tween a rock and hard place, it can get flat­tened or make a change to sur­vive and if it has to change then it will come with a cost,” said Prof Philip Goul­der, from the Univer­sity of Ox­ford.


The “cost” is a re­duced abil­ity to repli­cate, which in turn makes the virus less in­fec­tious and means it takes longer to cause Aids.

This weak­ened virus is then spread to other peo­ple and a slow cy­cle of “wa­ter­ing-down” HIV be­gins.

The team showed this process hap­pen­ing in Africa by com­par­ing Botswana, which has had an HIV prob­lem for a long time, and South Africa where HIV ar­rived a decade later.

Prof Goul­der told the BBC News web­site: “It is quite strik­ing. You can see the abil­ity to repli­cate is 10 per­cent lower in Botswana than South Africa and that’s quite ex­cit­ing.

“We are ob­serv­ing evo­lu­tion hap­pen­ing in front of us and it is sur­pris­ing how quickly the process is hap­pen­ing.

“The virus is slow­ing down in its abil­ity to cause dis­ease and that will help con­trib­ute to elim­i­na­tion.” Drug bonus The find­ings in Pro­ceed­ings of the Na­tional Academy of Sciences also sug­gested anti-retro­vi­ral drugs were forc­ing HIV to evolve into milder forms.

It showed the drugs would pri­mar­ily tar­get the nas­ti­est ver­sions of HIV and en­cour­age the milder ones to thrive.

Prof Goul­der added: “Twenty years ago the time to Aids was 10 years, but in the last 10 years in Botswana that might have in­creased to 12.5 years, a sort of in­cre­men­tal change, but in the big pic­ture that is a rapid change.

“One might imag­ine as time ex­tends this could stretch fur­ther and fur­ther and in the fu­ture peo­ple be­ing asymp­to­matic for decades.”

The group did cau­tion that even

a wa­tered-down ver­sion of HIV was still dan­ger­ous and could cause Aids.

HIV orig­i­nally came from apes or mon­keys, in which it is fre­quently a mi­nor in­fec­tion.

Prof Jonathan Ball, a vi­rol­o­gist at the Univer­sity of Not­ting­ham, told the BBC: “If the trend con­tin­ues then we might see the global pic­ture change — a longer dis­ease caus­ing much less trans­mis­sion.

“In the­ory, if we were to let HIV run its course then we would see a hu­man pop­u­la­tion emerge that was more resistant to the virus than we col­lec­tively are to­day - HIV in­fec­tion would even­tu­ally be­come almost harm­less.

“Such events have prob­a­bly hap­pened through­out his­tory, but we are talk­ing very large timescales.”

Prof An­drew Freed­man, a reader in in­fec­tious dis­eases at Cardiff Univer­sity, said this was an “in­trigu­ing study”.

He said: “By com­par­ing the epi­demic in Botswana with that which oc­curred some­what later in South Africa, the re­searchers were able to demon­strate that the ef­fect of this evo­lu­tion is for the virus to be­come less vir­u­lent, or weaker, over time.

“The wide­spread use of an­tiretro­vi­ral ther­apy may also have a sim­i­lar ef­fect and to­gether, th­ese ef­fects may con­trib­ute to the ul­ti­mate con­trol of the HIV epi­demic.”

But he cau­tioned HIV was “an aw­fully long way” from be­com­ing harm­less and “other events will su­per­sede that in­clud­ing wider ac­cess to treat­ment and even­tu­ally the de­vel­op­ment of a cure”. — BBC

The virus is adapt­ing to the hu­man im­mune sys­tem, weak­en­ing it­self in the process

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