13 September 2012

Africa: New Weapon in the War Against HIV

Photo: Edward Echwalu
Each circumcision requires the presence of at least two health workers

HIV and Aids and other sexually transmitted infections continue to burden young African women because of various reasons, chief among them cultural issues that prevent them from negotiating for safe sex. Over the years, the burden has become much heavier for the women most of whom know, but cannot use preventative measures like the female and male condoms because they first have to seek approval from their male partners.

This dilemma of placing their health on a tray, hand it over and have male partners decide whether to protect or expose them to HIV and other STIs still remains a challenge in Africa.

This challenge is not confined to poor rural women only, even the educated rich urbanites still cannot negotiate safe sex as this fear of being battered for carrying condoms in a handbag still casts a black cloud in the prevention of transmission of HIV.

But there is some good news in the pipeline.

Scientists have developed a vaginal ring embedded with an antiviral drug that could potentially protect women against the virus that causes Aids.

The plastic cervical ring contains MIV-150, a compound developed and being tested by scientists at the non-profit Population Council.

In experiments with macaques, only two of 17 female monkeys fitted ahead of time with the flexible ring became infected after being exposed to SHIV.

That virus combines the genetic material of human immunodeficiency virus, or HIV, and a monkey version called SIV. At the same time, 11 of the 16 macaques with vaginal rings that did not contain any active drug became SHIV positive when exposed to the genetically engineered virus.

The results represent an 83 percent protection against the sexually-transmitted infection.

Unlike male or female condoms, microbicides are a potential preventive option that women can easily control and do not require the co-operation, consent or even knowledge of the partner.

Currently, available HIV prevention techniques are often not feasible for many women who live in resource poor settings.

A microbicide is a chemical product that is applied in the female private parts or rectum with the intention of preventing the transmission of sexually transmitted infections including HIV.

Speaking to The Herald on the sidelines of the Aids Vaccine 2012 conference in Boston, Massachusetts, USA, Centre for the Aids Programme of Research in South Africa ( CAPRISA), director Dr Salim Kalim said new formulations, including ARVs in vaginal rings, hold new hope for improving adherence.

He said the HIV burden remained high in African women between the ages of 15 to 24 hence the need to find technology women can use while waiting for a vaccine.

He said 3 476 African women in countries that include Zimbabwe, Malawi, South Africa, Uganda and Zambia were undergoing effectiveness MTN 020 trials for the dapivirine vaginal ring candidate.

He said in Rwanda, Malawi and South Africa, another 1 650 women were also candidates of the dapivirine vaginal ring trial IPM 027.

Dr Salim said a microbicide-containing cervical ring would be simple to use and has advantages over short-term protection methods, such as gels or creams that are placed into the vagina or rectum before sexual intercourse.

He also said the vaginal ring would greatly empower women to protect themselves and their partners against HIV as circumcision has nothing to offer for women as they cannot control their husbands' condom use.

"We want to give women something they can control. Unlike male or female condoms, microbicides are a potential preventive option that women can easily control and do not require the co-operation, consent or even knowledge of the partner.

"It is not dependent upon someone applying it just before intercourse and, on a daily basis, it would be in there hopefully for a month, two months, three months. That's hopefully going to help the advantage," said Dr Salim.

He added that the ring is similar to a contraceptive ring that's currently on the market. Once inserted, it is held in place by muscles in the vaginal canal.

"We would want to make it easily accessible to women through health facilities. An example is to integrate into family planning services and make it more available through government hospitals where it will be given out for free in South Africa. As it stands it will only be available through prescription," he said.

He added that South Africa would produce microbicides for the rest of Africa and this explains why they have women from Zimbabwe and other African countries on trials.

The MIV-150 compound, according to Dr Salim, acts as a shield in the mucosal tissue at the cellular level, where HIV gains entry into the body.

He added that several new products were in the pipeline while the effort to get Tenofovir gel to women is in progress.

He said they learnt a lot from breakthrough infections in CAPRISA 004 that inflammation plays a key role in HIV acquisition.

"We learnt that pre-existing genital tract inflammation associated with increased susceptibility to HIV infection.

Even trials that were conducted in monkeys proved that genital inflammation facilitates SIV infection.

"In macaques, Li and Haase (2009) showed that genital tract inflammation is necessary for the initiation of a productive SIV infection in the female genital mucosa," said.

He added that incidence of multiple variant infections in women from the CAPRISA 004 Tenofovir gel microbicide trial and in women from the general population in the CAPRISA 002 acute infection cohort proved that tenofovir gel had no impact on the HIV transmission bottleneck.

He said women in the Tenofovir gel arm had preserved HIV specific T cell responses.

"HIV-1 specific Gag IFNyCD4+ Tcell responses were significantly higher in infected women from the Tenofovir gel arm compared to the placebo gel arm. Protection at the site of infection is critical.

Genital tenofovir levels correlate with protection, and we found no drug resistance in the earliest genital tract viruses ," he said.

Dr Salim explained that the difference between the drug-infused ring and a topical microbicide may be that the drug delivery device offers continuous protection against the virus with MIV-150, while other microbicides wear off quickly.

Testing the monkeys two weeks after exposure to SHIV, researchers found the ring provided significant protection whether it had been inserted two weeks or just 24 hours earlier.

Future experiments will look at how long a ring containing MIV-150 must remain inserted to be fully effective.

He added that researchers are working hard to try and develop a ring that can be left in place for three months.

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