This Week in HIV Research: Long-Term Nonprogressors Have Greater Thymic Function; and HCV Reinfection Rates Examined

This week, a study finds that thymic function, which is associated with higher CD4 counts in people with HIV, is greater in long-term nonprogressors. Another study finds that for people with HIV, hepatitis C reinfection risk is higher for those who use injection drugs. And our last study looked at the significance of HPV genotypes among women with HIV who also had cervical cancer. To beat HIV, you have to follow the science!

Thymic Function Greater in Long-Term Nonprogressors

Higher thymic function is associated with higher CD4 cell levels in people living with HIV, while thymic function failure is associated with HIV progression, a study published in Clinical Infectious Diseases found.

Researchers analyzed the thymus gland's function in 774 people living with HIV, including long-term nonprogressors (LTNPs) and people who acquired HIV from their mothers (and were less than 18 years old). LTPNs control their HIV levels for a long time without antiretroviral medications. Those vertically infected had the best thymic function, followed by LTNPs and regular HIV progressors who were not on antiretroviral treatment.

Analysis of an LTNP subgroup of elite controllers showed that high CD4 T-cell maintenance is not linked to CD4 cell counts. The thymus of LTPNs functions at higher than normal levels, helping to produce naive T cells. This mechanism may account for that group's ability to naturally control HIV levels, study authors hypothesized.

HCV Reinfection Risk Greater Among High-Frequency Intravenous Drug Users

People living with HIV who frequently use intravenous drugs are six times more likely to be reinfected with hepatitis C (HCV) than former intravenous drug users (IDUs) living with HIV, an analysis published in Clinical Infectious Diseases found.

Researchers examined data from 257 participants in the Canadian Co-infection Cohort. About three-quarters had used intravenous drugs at some point and 14% were still injecting drugs. A third of participants were men who have sex with men (MSM). Everyone had achieved sustained viral response (SVR) of their HCV, and most were on antiretroviral treatment with undetectable HIV levels.

Statistical extrapolation yielded HCV reinfection rates of 58 per 1,000 person years (PYs) among frequent IDUs, 22 per 1,000 PYs for infrequent IDUs and 26 per 1000 PYs for MSM who reported high-risk sexual activity, and 16 per 1,000 PYs for MSM reporting low-risk sexual activities and a reference group composed mostly of former IDUs. All figures applied to the first year of follow-up after SVR. Study authors cautioned, however, that the low rate of reinfections led to a small sample size from which to extrapolate.

HPV Diagnoses in Africa Could Be Guided by Prevalence of Specific Genotypes

HPV 16 is the most carcinogenic human papillomavirus (HPV) genotype among women living with HIV (WHIV) across the globe, but HPV 45 is important in Africa, a cross-sectional analysis published in Clinical Infectious Diseases showed.

Researchers reviewed data from 86 studies involving close to 20,000 women living with HIV who had been tested for HPV. Most of the women were from Africa, including 770 of the almost 800 who had invasive cervical cancers (ICCs), the most serious form of cervical lesions.

While almost half of African WHIV with ICCs tested positive for HPV 16 and almost a quarter had HPV 18, 15% also had HPV 45. The corresponding numbers for the (few) European/North American WHIVs with ICCs were 63% and 13% for HPV 16 and 18, respectively, and 6% for HPV 45. These results may help to "prioritiz[e] the diagnostic workup of WHIV in low-infrastructure settings," where full genotyping of all WHIV who test positive for HPV may overburden the system, study authors wrote.