In heterosexuals, transmitted HIV strains often resemble original infecting virus

September 20, 2012

A new study has found that even though HIV diversifies widely within infected individuals over time, the virus strains that ultimately are passed on through heterosexual transmission often resemble the strain of virus that originally infected the transmitting partner. Learning the characteristics of these preferentially transmitted HIV strains may help advance HIV prevention efforts, particularly with regard to an HIV vaccine, according to the scientists who conducted the study. The research was led by Andrew D. Redd, Ph.D., staff scientist, and Thomas C. Quinn, M.D., senior investigator, both in the Laboratory of Immunoregulation of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.

Dr. Redd and colleagues examined particular genetic sequences of HIV in blood samples collected between 1994 and 2002 from hundreds of HIV-infected heterosexuals participating in the Rakai Community Cohort Study in Rakai District, Uganda. The scientists found a significant increase in population-wide HIV genetic diversity among infected individuals during the 8-year period, yet the amount of genetic change was significantly greater within individuals than across the population as a whole. To explain this phenomenon, the scientists hypothesized that the of HIV at the was limited because only certain strains of the virus within each person were responsible for subsequent sexual transmissions.

To test this hypothesis, the scientists examined the of HIV strains in 31 couples where heterosexual transmission occurred. Through three increasingly comprehensive analyses, they compared HIV strains in the transmitting partner at points before and around the estimated time of with the strain in the newly infected partner around the time of transmission. In 22 of the couples, or 71 percent of those studied, the in the blood of the newly infected partner were more closely related to those found in the blood of the transmitting partner at the earliest available time point than to strains present around the time of transmission. According to Dr. Redd, this finding demonstrates that in the heterosexual transmission of HIV, the frequent natural selection of viral strains from early in the infection of the transmitting partner reduces viral diversity at the population level.

Moreover, in four couples, the newly acquired strain was highly similar or identical to specific variants found in the transmitting partner at both the earliest time point and the time of transmission. The scientists hypothesize that these highly transmissible HIV strains from early infection were sustained in the blood at low levels or sequestered in certain cells for transmission at a later time.

Related research by other scientists shows that HIV strains found in infected individuals during the early stages of infection have diversified little from the strain that caused infection. Thus, the fact that these early HIV strains somehow are maintained or persist at low levels for transmission later suggests they may have an evolutionary advantage at crossing the genital barrier and causing infection, compared with that predominate later in infection, according to Dr. Redd.

This research was co-funded by the NIAID Division of Intramural Research; NIAID grants numbers R01A134826, R01A134265 and R01AI077473; the World Bank STI Project; the Henry M. Jackson Foundation; the Fogarty Foundation; and the Bill and Melinda Gates Institute for Population and Reproductive Health.

Explore further: New data suggests HIV superinfection rate comparable to initial HIV infection

More information: AD Redd et al. Previously transmitted HIV-1 viral strains are preferentially transmitted during subsequent sexual transmission. Journal of Infectious Diseases DOI 10.1093/infdis/jis503 (2012).

Related Stories

New data suggests HIV superinfection rate comparable to initial HIV infection

June 7, 2012
HIV superinfection, when a person with HIV could acquire a second, new strain of HIV, may occur as often as initial HIV infection in the general population in Uganda, a study suggests.

Viral load a major factor affecting risk of sexually transmitting HIV

January 12, 2012
The level of HIV-1 in the blood of an HIV-infected partner is the single most important factor influencing risk of sexual transmission to an uninfected partner, according to a multinational study of heterosexual couples in ...

Researchers discuss challenges to developing broadly protective HIV vaccines

September 7, 2011
The human body can produce powerful antibodies that shield cells in the laboratory against infection by an array of HIV strains. In people, however, recent research shows that these broadly neutralizing antibodies are not ...

Hope for more options in couples where one partner is HIV positive

November 15, 2011
In sub-Saharan Africa, couples in long-term relationships where one partner is HIV-positive and the other is HIV-negative (HIV serodiscordant couples) could benefit from anti-AIDS drugs (antiretroviral therapy) given either ...

Recommended for you

Study suggests a way to stop HIV in its tracks

December 1, 2017
When HIV-1 infects an immune cell, the virus travels to the nucleus so quickly there's not enough time to set off the cell's alarm system.

Discovery puts the brakes on HIV's ability to infect

November 30, 2017
Viewed with a microscope, the virus faintly resembles a pineapple—the universal symbol of welcome. But HIV, the virus that causes AIDS, is anything but that. It has claimed the lives of more than 35 million people so far.

Rising levels of HIV drug resistance

November 30, 2017
HIV drug resistance is approaching and exceeding 10% in people living with HIV who are about to initiate or reinitiate first-line antiretroviral therapy, according to the largest meta-analysis to date on HIV drug resistance, ...

Male circumcision and antiviral drugs appear to sharply reduce HIV infection rate

November 29, 2017
A steep drop in the local incidence of new HIV infections accompanied the rollout of a U.S.-funded anti-HIV program in a large East-African population, according to a study led by researchers at Johns Hopkins Bloomberg School ...

Combination HIV prevention reduces new infections by 42 percent in Ugandan district

November 29, 2017
A study published today in the New England Journal of Medicine provides real-world evidence that implementing a combination of proven HIV prevention measures across communities can substantially reduce new HIV infections ...

Research on HIV viral load urges updates to WHO therapy guidelines

November 24, 2017
A large cohort study in South Africa has revealed that that low-level viraemia (LLV) in HIV-positive patients who are receiving antiretroviral treatment (ART) is an important risk factor for treatment failure.

4 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Tom_Hennessy
1 / 5 (2) Sep 20, 2012
This would give credence to the oxidation of virus causing virus mutation. Virus' are known to mutate in a situation of high oxidative stress and the theory is those who ORIGINALLY had the virus , homosexuals and drug users , are already IN this high oxidative state , hence their problems , and which is WHY heterosexuals when they DO catch the virus don't cause the virus to mutate. Because , the heterosexuals aren't IN a high oxidative state when presented with the virus.
freethinking
1 / 5 (1) Sep 21, 2012
Aids, very hard to get through normal sex. Best way to catch AIDS do IV drugs, or participate in abnormal sexual practices.

If other disease research would receive the same funding as AIDS research, many diseases that affect many more people, than AIDS may be cured. How many lives could have been saved if money spent on a disease caused by one particular abnormal lifestyle would have been spent on diseases that are easily communicable.

AIDS can be prevented, you don't need to catch AIDS. If you don't practice abnormal sexual practices or take illegal IV drugs, your odds of catching AIDS very remote.
loneislander
1 / 5 (1) Sep 23, 2012
What would be an "abnormal" sex practice? Not having sex at all?
freethinking
1 / 5 (1) Sep 23, 2012
Sexual acts done by homosexuals, if you seriously don't know which homosexual acts spread AIDS IM me and I'll explain.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.