As part of an ongoing study of early human immunodeficiency virus type 1 (HIV-1) infection in sub-Saharan African countries, we have identified 134 seroconverters (SCs) with distinct acute-phase (peak) and early chronic-phase (set-point) viremias. SCs with class I human leukocyte antigen (HLA) variants B*44 and B*57 had much lower peak viral loads (VLs) than SCs without these variants (adjusted linear regression beta values of ؊1.08 ؎ 0.26 log 10 [mean ؎ standard error] and ؊0.83 ؎ 0.27 log 10 , respectively; P < 0.005 for both), after accounting for several nongenetic factors, including gender, age at estimated date of infection, duration of infection, and country of origin. These findings were confirmed by alternative models in which major viral subtypes (A1, C, and others) in the same SCs replaced country of origin as a covariate (P < 0.03). Both B*44 and B*57 were also highly favorable (P < 0.03) in analyses of set-point VLs. Moreover, B*44 was associated with relatively high CD4 ؉ T-cell counts during early chronic infection (P ؍ 0.02). Thus, at least two common HLA-B variants showed strong influences on acute-phase as well as early chronic-phase VL, regardless of the infecting viral subtype. If confirmed, the identification of B*44 as another favorable marker in primary HIV-1 infection should help dissect mechanisms of early immune protection against HIV-1 infection.HIV-1 viral load (VL or viremia), in the typical form of viral RNA concentration in plasma, has both epidemiological and clinical implications because of its dual impact on transmission (18,30,71) and on the rate of disease progression (58, 59). In most studies, a quantitative measure of VL is used without reference to estimated date of infection (EDI), under the assumption that patients are seldom observed during acute-phase (peak) infection and that the early chronic-phase (set-point) VL is usually stable for years in patients with no apparent manifestations of immunodeficiency. Factors known or suspected to influence VL range from viral mutations (changes in replication fitness or switches in coreceptor tropism) (15,28,39,72) to host genes that govern innate and adaptive immune responses (54,75,81,83,84,86).Within the human nuclear genome, human leukocyte antigen (HLA) class I genes are the most convincing (and universally applicable) quantitative trait loci for HIV-1 viremia (14,16,17,66). However, the individual HLA alleles, haplotypes, and supertypes with reported impacts on HIV-1 VL are not always clear because their distribution and patterns of linkage disequilibrium often differ from one population to another (7,53,63). Consensus findings have been limited to a few variants like B*27 and B*57 (9, 80), although more recent work based on African cohorts has yielded consensus results for additional variants, including A*74, B*13, and B*81, that are often favorable (49, 81). The HLA class I heavy chains encoded by these alleles differentially present highly conserved viral epitopes for cytotoxic T-lymphocyte (CTL) responses (5,29,39). Su...