Browsing by Author "Kisitu, Grace P."

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    The Collaborative African Genomics Network (CAfGEN): Applying Genomic technologies to probe host factors important to the progression of HIV and HIV-tuberculosis infection in sub-Saharan Africa [version 1; referees: awaiting peer review]
    (AAS open research, 2018) Mboowa, Gerald; Mwesigwa, Savannah; Katagirya, Eric; Retshabile, Gaone; Mlotshwa, Busisiwe C.; Williams, Lesedi; Kekitiinwa, Adeodata; Kateete, David; Wampande, Eddie; Wayengera, Misaki; Nsangi Kintu, Betty; Kisitu, Grace P.; Kyobe, Samuel; Brown, Chester W.; Hanchard, Neil A.; Mardon, Graeme; Joloba, Moses; Anabwani, Gabriel; Pettitt, Ed; Tsimako-Johnstone, Masego; Kasvosve, Ishmael; Maplanka, Koketso; Mpoloka, Sununguko W.; Hlatshwayo, Makhosazana; Matshaba, Mogomotsi
    The Human Heredity and Health in Africa consortium (H3Africa) was conceived to facilitate the application of genomics technologies to improve health across Africa. Here, we describe how the Collaborative African Genomics Network (CAfGEN) of the H3Africa consortium is using genomics to probe host genetic factors important to the progression of HIV and HIV-tuberculosis (TB) coinfection in sub-Saharan Africa. Methods: CAfGEN is an H3Africa collaborative centre comprising expertise from the University of Botswana; Makerere University; Baylor College of v
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    Exome Sequencing Reveals a Putative Role for HLA-C*03:02 in Control of HIV-1 in African Pediatric Populations
    (Frontiers in Genetics, 2021) Kyobe, Samuel; Mwesigwa, Savannah; Kisitu, Grace P.; Farirai, John; Katagirya, Eric; Mirembe, Angella N.; Ketumile, Lesego; Wayengera, Misaki; Ashaba Katabazi, Fred; Kigozi, Edgar; Wampande, Edward M.; Retshabile, Gaone; Mlotshwa, Busisiwe C.; Williams, Lesedi; Morapedi, Koketso; Kasvosve, Ishmael; Kyosiimire-Lugemwa, Jacqueline; Nsangi, Betty; Tsimako-Johnstone, Masego; Brown, Chester W.; Joloba, Moses; Anabwani, Gabriel; Bhekumusa, Lukhele; Mpoloka, Sununguko W.; Mardon, Graeme; Matshaba, Mogomotsi; Kekitiinwa, Adeodata; Hanchard, Neil A.
    Human leucocyte antigen (HLA) class I molecules present endogenously processed antigens to T-cells and have been linked to differences in HIV-1 disease progression. HLA allelotypes show considerable geographical and inter-individual variation, as does the rate of progression of HIV-1 disease, with long-term non-progression (LTNP) of disease having most evidence of an underlying genetic contribution. However, most genetic analyses of LTNP have occurred in adults of European ancestry, limiting the potential transferability of observed associations to diverse populations who carry the burden of disease. This is particularly true of HIV-1 infected children. Here, using exome sequencing (ES) to infer HLA allelotypes, we determine associations with HIV- 1 LTNP in two diverse African pediatric populations. We performed a case-control association study of 394 LTNPs and 420 rapid progressors retrospectively identified from electronic medical records of pediatric HIV-1 populations in Uganda and Botswana. We utilized high-depth ES to perform high-resolution HLA allelotyping and assessed evidence of association between HLA class I alleles and LTNP. Sixteen HLA alleles and haplotypes had significantly different frequencies between Uganda and Botswana, with allelic differences being more prominent in HLA-A compared to HLA-B and C allelotypes. Three HLA allelotypes showed association with LTNP, including a novel association in HLA-C (HLA-B 57:03, aOR 3.21, Pc = 0.0259; B 58:01, aOR 1.89, Pc = 0.033; C 03:02, aOR 4.74, Pc = 0.033). Together, these alleles convey an estimated population attributable risk (PAR) of non-progression of 16.5%. We also observed novel haplotype associations with HLA-B 57:03-C 07:01 (aOR 5.40, Pc = 0.025) and HLA-B 58:01- C 03:02 (aOR 4.88, Pc = 0.011) with a PAR of 9.8%, as well as a previously unreported independent additive effect and heterozygote advantage of HLA-C 03:02 with B 58:01 (aOR 4.15, Pc = 0.005) that appears to limit disease progression, despite weak LD (r2 = 0.18) between these alleles. These associations remained irrespective of gender or country. In one of the largest studies of HIV in Africa, we find evidence of a protective effect of canonical HLA-B alleles and a novel HLA-C association that appears to augment existing HIV-1 control alleles in pediatric populations. Our findings outline the value of using multi-ethnic populations in genetic studies and offer a novel HIV-1 association of relevance to ongoing vaccine studies.
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    Prevalence and correlates of HIV testing among adolescents 10–19 years in a post-conflict pastoralist community of Karamoja region, Uganda
    (BMC public health, 2018) Ssebunya, Rogers N.; Wanyenze, Rhoda K.; Namale, Leticia; Lukolyo, Heather; Kisitu, Grace P.; Nahirya-Ntege, Patricia; Kekitiinwa, Adeodata
    Adolescents are a priority group in HIV prevention and treatment. This study sought to determine the prevalence and correlates of HIV testing services (HTS) among adolescents in the pastoralist post-conflict area of Karamoja sub region, Uganda. Methods: A cross sectional study of 1439 adolescents aged 10–19 years, attending nine public health facilities in five of the seven districts of Karamoja, was conducted between August to September 2016. Adolescents were consecutively selected and interviewed using structured interviewer administered questionnaires. All respondents who had never tested for HIV were offered HTS. The main outcome was ever tested for HIV. Correlates of ever tested were analyzed using multivariate logistic regression model. Results: Of the 1439 adolescents, 904 (62.8%) were females, 1203 (83.6%) were aged 15–19 years, 618 (43.0%) had attained primary education and 885 (61.5%) had ever had sex. Overall 1177 (81.8%) had ever tested and received HIV results. Older age (15–19 years) (adj.OR = 2.71, 95% CI: 1.85–3.96), secondary level education or higher (adj.OR = 2.33, 95% CI: 1.33–4.10), and ever had sex (adj.OR = 2.03, 95% CI: 1.42–2.90) were associated with higher odds of HIV testing. Of the 262 who had never tested, 169 (64.5%) accepted testing and 2.4% were HIV positive. Reasons for not accepting the test included fear of being tested and not ready for an HIV test because of perceived suffering HIV positive clients go through. Conclusion: Awareness of HIV status and uptake of HTS among adolescents in this hard-to-reach post-conflict region was high and close to the global UNAIDS target of 90%. However, the HIV prevalence of 2.4% among the non-testers who accepted to be tested was high and emphasises the need for targeted testing to reach the undiagnosed HIV infected adolescents in this region.
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    Unmapped exome reads implicate a role for Anelloviridae in childhood HIV-1 long-term non-progression
    (NPJ Genomic Medicine, 2021) Mwesigwa, Savannah; Williams, Lesedi; Retshabile, Gaone; Katagirya, Eric; Mboowa, Gerald; Mlotshwa, Busisiwe; Kyobe, Samuel; Kateete, David P.; Mujjwiga Wampande, Eddie; Wayengera, Misaki; Wata Mpoloka, Sununguko; Mirembe, Angella N.; Kasvosve, Ishmael; Morapedi, Koketso; Kisitu, Grace P.; Kekitiinwa, Adeodata R.; Anabwani, Gabriel; Joloba, Moses L.; Matovu, Enock; Mulindwa, Julius; Noyes, Harry; Botha, Gerrit; Brown, Chester W.; Mardon, Graeme; Matshaba, Mogomotsi; Hanchard, Neil A.
    Human immunodeficiency virus (HIV) infection remains a significant public health burden globally. The role of viral co-infection in the rate of progression of HIV infection has been suggested but not empirically tested, particularly among children. We extracted and classified 42 viral species from whole-exome sequencing (WES) data of 813 HIV-infected children in Botswana and Uganda categorised as either long-term non-progressors (LTNPs) or rapid progressors (RPs). The Ugandan participants had a higher viral community diversity index compared to Batswana (p = 4.6 × 10−13), and viral sequences were more frequently detected among LTNPs than RPs (24% vs 16%; p = 0.008; OR, 1.9; 95% CI, 1.6–2.3), with Anelloviridae showing strong association with LTNP status (p = 3 × 10−4; q = 0.004, OR, 3.99; 95% CI, 1.74–10.25). This trend was still evident when stratified by country, sex, and sequencing platform, and after a logistic regression analysis adjusting for age, sex, country, and the sequencing platform (p = 0.02; q = 0.03; OR, 7.3; 95% CI, 1.6–40.5). Torque teno virus (TTV), which made up 95% of the Anelloviridae reads, has been associated with reduced immune activation. We identify an association between viral co-infection and prolonged AIDs-free survival status that may have utility as a biomarker of LTNP and could provide mechanistic insights to HIV progression in children, demonstrating the added value of interrogating off-target WES reads in cohort studies.
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    Whole-Exome Sequencing Reveals Uncaptured Variation and Distinct Ancestry in the Southern African Population of Botswana
    (The American Journal of Human Genetics, 2018) Retshabile, Gaone; Mlotshwa, Busisiwe C.; Williams, Lesedi; Mwesigwa, Savannah; Mboowa, Gerald; Huang, Zhuoyi; Rustagi, Navin; Swaminathan, Shanker; Katagirya, Eric; Kyobe, Samuel; Wayengera, Misaki; Kisitu, Grace P.; Kateete, David P.; Wampande, Eddie M.; Maplanka, Koketso; Kasvosve, Ishmael; Pettitt, Edward D.; Matshaba, Mogomotsi; Nsangi, Betty; Marape, Marape; Tsimako-Johnstone, Masego; Brown, Chester W.; Yu, Fuli; Kekitiinwa, Adeodata; Joloba, Moses; Mpoloka, Sununguko W.; Mardon, Graeme; Anabwani, Gabriel; Hanchard, Neil A.
    Large-scale, population-based genomic studies have provided a context for modern medical genetics. Among such studies, however, African populations have remained relatively underrepresented. The breadth of genetic diversity across the African continent argues for an exploration of local genomic context to facilitate burgeoning disease mapping studies in Africa.We sought to characterize genetic variation and to assess population substructure within a cohort of HIV-positive children from Botswana—a Southern African country that is regionally underrepresented in genomic databases. Using whole-exome sequencing data from 164 Batswana and comparisons with 150 similarly sequenced HIV-positive Ugandan children, we found that 13%–25% of variation observed among Batswana was not captured by public databases. Uncaptured variants were significantly enriched (p ¼ 2.2 3 10 16) for coding variants with minor allele frequencies between 1% and 5% and included predicted-damaging non-synonymous variants. Among variants found in public databases, corresponding allele frequencies varied widely, with Botswana having significantly higher allele frequencies among rare (<1%) pathogenic and damaging variants. Batswana clustered with other Southern African populations, but distinctly from 1000 Genomes African populations, and had limited evidence for admixture with extra-continental ancestries. We also observed a surprising lack of genetic substructure in Botswana, despite multiple tribal ethnicities and language groups, alongside a higher degree of relatedness than purported founder populations from the 1000 Genomes project. Our observations reveal a complex, but distinct, ancestral history and genomic architecture among Batswana and suggest that disease mapping within similar Southern African populations will require a deeper repository of genetic variation and allelic dependencies than presently exists.