Washington, Genetic variations and not complying with treatment regimens may account for some failures of an anti-HIV drug to treat and prevent the infection.
The drug Tenofovir, marketed as Viread, is processed differently according to cell locations, the study said.
This is to see if the drug is eventually marketed as a topical gel, it can work differently depending on whether it is applied to the vagina or the rectum.
“Our results suggest that in future, before prescribing tenofovir to a patient, a doctor could order genetic testing and know in advance if it works, and prescribe a different drug if it won’t,” said Namandje Bumpus, associate professor of medicine at the Johns Hopkins University School of Medicine.
In the study described in the journal EBio-Medicine, the team focused on a search for the human enzymes that convert tenofovir from its original form to an activated one that combats HIV.
The team “knocked out” genes for phosphate-adding enzymes one by one, then exposed the tissues’ cells to tenofovir.
They found that the enzyme called pyruvate kinase was different from that which performed the second activation step in the colorectal tissues.
The team sequenced the genes of 142 women who had participated in a clinical trial of tenofovir to look for genetic variations that might have affected the function of the enzyme.
They found 71 such variants, several of which a computer model predicted would make the enzyme ineffective.
Altogether, eight percent of the women had genetic variants that were likely to make them unable to convert tenofovir to its activated form.
“Tenofovir has been shown in trials to be very effective, so when it does not work, researchers and clinicians tend to assume the individual just was not taking the drug as directed,” Bumpus said.
Pakistan is registering approximately 20,000 new HIV infections annually, the highest rate of increase among all countries in the region, warns the World Health Organization (WHO).
The international body says mortality among Pakistanis living with the virus, which causes the deadly AIDS disease, is also rising, in spite of the availability of lifesaving antiretroviral therapy.
The latest government figures show that only 16 percent of the estimated 150,000 people living with HIV had been tested and only 9 percent have access to lifesaving treatment.
“The remaining 135,000 people are walking around in the communities as carriers of (HIV) infection who are ready to transmit infections to those who are not infected, even to their unborn babies,” Dr. Saima Paracha of the National AIDS Control Program, told VOA.
Officials say the HIV epidemic in Pakistan remains largely concentrated among the key populations, including people who inject drugs, the transgender community, sex workers and their clients and men who have sex with men.
“The drivers of infection are now the sexual networks and they are ready to spill the infection into the general public,” Dr. Paracha cautioned.
Paracha says the Pakistani government offers free HIV testing and treatment, but she notes the marginalized key populations continue face widespread stigma and discrimination in the society.
The fear of maltreatment, and punitive actions by law enforcers impacts the willingness of these populations to pursue testing, which remains a major challenge facing national efforts to treat and prevent the spread of HIV, she lamented.
Official estimates show that Pakistan has seen a 45 percent increase in new HIV infections since 2010.
“The number of new HIV infections will continue to increase dramatically if implementation rates of intervention remain at current levels,” said Dr. Nima Saeed Abid, country head of WHO.
An official statement issued in connection with World AIDS Day quoted him as saying that Pakistan has the lowest rate of all regional countries in diagnosing people who are infected and linking them to care and treatment.
Naila Bashir, who heads the HIV treatment center at Islamabad’s Pakistan Institute of Medical Sciences (PIMS), told VOA the facility receives up to 40 new HIV patients every month, underscoring the alarming increase in the number of infections.
The center was established in 2005 and the number of patients has since increased from 22 to more than 3,000, including men, women and children of all ages, said Dr. Bashir.
HIV has never been a priority program in the national health system and the recent abolition of the federal health ministry and the devolution of its functions to the provinces, which lacked preparedness and capacity, have led to the increase in infections, say WHO experts in the country. However, they acknowledge the new government of Prime Minister Imran Khan is giving priority to tackling health emergencies in Pakistan, including HIV.
Federal Minister for National Health Services Regulation and Coordination, Aamir Mehmood Kiyani, says the government is working on a strategy to remove barriers and challenges in protecting people from HIV infections.
Kiyani told a seminar in Islamabad that since taking office three months ago, the government has moved to established 12 new HIV treatment centers while overall 33 such facilities have been working throughout Pakistan.
U.N. officials say the Pakistan government urgently needs to redouble efforts to “de-stigmatize HIV testing, advocate for confidential, non-discriminatory, community based care models and raise awareness about disease transmission, prevention treatment” to achieve reductions in new infections in affected populations. (VOA)