Major histocompatibility complex class II (HLA-DRB and -DQB) allele frequencies in Botswana: association with human immunodeficiency virus type 1 infection

Abstract

Southern Africa is facing an unprecedented public health crisis due to the high prevalence of human immunodeficiency virus type 1 (HIV-1). Vaccine development and testing efforts, mainly based on elicitation of HIV-specific T cells, are under way. To understand the role of human leukocyte antigen (HLA) class II alleles in HIV pathogenesis and to facilitate HLA-based HIV-1 vaccine design, we analyzed the frequencies of HLA class II alleles within the southern African country of Botswana. Common HLA class II alleles were identified within the Botswana population through the molecular genotyping of DRB and DQB1 loci. The DRB1 allele groups DRB1*01, DRB1*02/15, DRB1*03, DRB1*11, and DRB1*13 were encountered at frequencies above 20%. Within the DQB1 locus, DQB1*06 (47.7%) was the most common allele group, followed by DQB1*03 (39.2%) and DQB1*04 (25.8%). We found that DRB1*01 was more common in HIV-negative than in HIV-positive individuals and that those who expressed DRB1*08 had lower median viral loads. We demonstrate that the frequencies of certain HLA class II alleles in this Botswana population differ substantially from those in North American populations, including African-Americans. Common allele groups within Botswana cover large percentages of other African populations and could be targeted in regional vaccine designs.

FIG. 1.

Botswana DRB1 allele group frequencies compared with those of other populations. The data for the African populations are taken from the work of Dunand et al. (10) and this study (for Botswana), while those for North American Caucasians and African-Americans are taken from the work of Sintasath et al. (46). Data were not available for black West Africans, East Africans, and South Africans for allele groups DRB1*01, DRB1*04, and DRB1*07 to DRB1*10. The horizontal line represents the calculated 95% confidence interval for each population frequency. Plus signs indicate population frequencies that are significantly different from those for Botswana (P < 0.05).

FIG. 1.

Botswana DRB1 allele group frequencies compared with those of other populations. The data for the African populations are taken from the work of Dunand et al. (10) and this study (for Botswana), while those for North American Caucasians and African-Americans are taken from the work of Sintasath et al. (46). Data were not available for black West Africans, East Africans, and South Africans for allele groups DRB1*01, DRB1*04, and DRB1*07 to DRB1*10. The horizontal line represents the calculated 95% confidence interval for each population frequency. Plus signs indicate population frequencies that are significantly different from those for Botswana (P < 0.05).