Iron, Haptoglobin Phenotype, and HIV-1 Viral Load: A Cross-Sectional Study Among Pregnant Zimbabwean Women

BACKGROUND:Viral load is a determinant of HIV-1 progression and transmission. Iron status and the phenotype of haptoglobin, a heme-binding acute phase reactant, may be determinants of viral load. We aimed to describe the effect of iron status, haptoglobin phenotype (Hp), and other predictors on HIV-1 viral load. METHODS:Based on a cross-sectional study among 1669 antenatal care attenders (22-35 weeks) in Zimbabwe, 526 (31.5%) were found to be HIV infected. The role of season, age, gravidity, gestational age, malaria parasitemia, Hp, and elevated serum α1-antichymotrypsin (ACT) as well as serum ferritin, folate, retinol, and β-carotene on HIV viral load among the 526 HIV-infected women was assessed using multiple linear regression analysis. RESULTS:The distribution of Hp 1-1 (32%), Hp 2-1 (48%), and Hp 2-2 (20%) was not different from that of 53 uninfected women. Mean viral load was 3.85 log10 (95% CI3.77-3.93) genome equivalents (geq)/mL, ranging from 3.77 (95% CI3.64-3.90) geq/mL in women with Hp 1-1 to 4.05 (95% CI3.81-4.21) geq/mL in women with Hp 2-2. With elevated serum ACT controlled for, women with Hp 2-2 had viral loads twice (95% CI1.4-4.0, p = .002) that of women with Hp 1-1, whereas those with serum ferritin 24 μg/L. Viral loads were also higher in women enrolled in the early rainy season compared with the dry season, in gravidae 4+ compared with gravidae 1 through 3, and in those with moderately elevated compared with low serum α1-antichymotrypsin, but neither age, gestational age, serum folate, serum retinol, nor serum β-carotene were predictors. CONCLUSION:Storage iron, Hp 2-2, and elevated ACT are independent positive predictors of HIV-1 viral load. The positive relationship between serum ferritin and viral load was not the result of an acute phase response or iron accumulation with advanced HIV infection. A possible detrimental role of iron in HIV infection would have serious public health implications.