KIR2DL1 gene is a surrogate marker of protection against infection-related hospitalization among HIV-1 unexposed versus exposed uninfected infants in Cameroon.

BACKGROUND: HIV-exposed uninfected infants (HEU) appear more vulnerable to infections compared to their HIV-unexposed uninfected (HUU) peers, generally attributed to poor passive immunity acquired from the mother. This may be due to some genetic factors that could alter the immune system. We thus sought to determine the distribution of Killer Cell Immunoglobulin-Like Receptors (KIRs) genes in HEU versus HUU and study their associations with the occurrence of infection-related hospitalization. METHODS: A cohort study was conducted from May 2019 to April 2020 among HEU and HUU infants, including their follow-up at weeks 6, 12, 24, and 48, in reference pediatric centers in Yaoundé-Cameroon. The infant HIV status and infections were determined. A total of 15 KIR genes were investigated using the sequence-specific primer polymerase chain reaction (PCR-SSP) method. The KIR genes that were significantly associated with HIV-1 status (HEU and HUU) were analyzed for an association with infection-related hospitalizations. This was only possible if, and to the extent that, infection-related hospitalizations varied significantly according to status. Multivariate logistic regression analyses were conducted to determine the association between KIR gene content variants and HIV status, while considering a number of potential confounding factors. Furthermore, the risk was quantified using relative risk, odds ratio, and a 95% confidence interval. The Fisher exact test was employed to compare the frequency of occurrences. A p-value of less than 0.05 was considered statistically significant. RESULTS: In this cohort, a total of 66 infants participated, but only 19 acquired infections requiring hospitalizations (14.81%, 04/27 HUU and 38.46%, 15/39 HEU, p = 0.037). At week 48 (39 HEU and 27 HUU), the relative risk (RR) for infection-related hospitalizations was 2.42 (95% CI: 1.028-5.823) for HEU versus HUU with OR 3.59 (1.037-12.448). KIR2DL1 gene was significantly underrepresented in HEU versus HUU (OR = 0.183, 95%CI: 0.053-0.629; p = 0.003), and the absence of KIR2DL1 was significantly associated with infection-related hospitalization (p < 0.001; aOR = 0.063; 95%CI: 0.017-0.229). CONCLUSION: Compared to HUU, the vulnerability of HEU is driven by KIR2DL1, indicating the protective role of this KIR against infection and hospitalizations.

Exhaled nitric oxide is associated with inflammatory biomarkers and risk of acute respiratory exacerbations in children with HIV-associated chronic lung disease.

OBJECTIVES: Chronic lung disease is a recognized complication in children with HIV. Acute respiratory exacerbations (ARE) are common among this group and cause significant morbidity. Exhaled nitric oxide (eNO) is a known marker of local airway inflammation. We investigated the association between eNO and ARE, biomarkers of systemic inflammation, and the effect of azithromycin on eNO levels. METHODS: Individuals aged 6-19 years with HIV-associated chronic lung disease in Harare, Zimbabwe, were enrolled in a placebo-controlled randomized trial investigating the effect of 48-week azithromycin treatment on lung function and ARE. eNO levels and biomarkers were measured at inclusion and after treatment in a consecutively enrolled subset of participants. Linear regression and generalized linear models were used to study associations between eNO and ARE, biomarkers, and the effect of azithromycin on eNO levels. RESULTS: In total, 172 participants were included in this sub-study, 86 from the placebo group and 86 from the azithromycin group. Participants experiencing at least one ARE during follow-up had significantly higher eNO levels at baseline than participants who did not (geometric mean ratio 1.13, 95% confidence interval [CI] 1.03-1.24, p = 0.015), adjusted for trial arm, age, sex and history of tuberculosis. Matrix metalloproteinase (MMP)-3, -7, and -10 were significantly associated with higher baseline eNO levels. At 48 weeks, azithromycin treatment did not affect eNO levels (geometric mean ratio 0.86, 95% CI 0.72-1.03, p = 0.103). CONCLUSION: Higher baseline eNO levels were a risk factor for ARE. eNO was associated with proinflammatory biomarkers previously found to contribute to the development of chronic lung disease. The potential use of eNO as a marker of inflammation and risk factor for ARE in HIV-associated chronic lung disease needs further investigation.

Shorter Granulocyte Telomeres Among Children and Adolescents With Perinatally Acquired Human Immunodeficiency Virus Infection and Chronic Lung Disease in Zimbabwe.

BACKGROUND: Chronic lung disease (CLD) has been reported among African children with perinatally acquired human immunodeficiency virus (HIV) infection (C-PHIV), despite combination antiretroviral therapy (cART). In adults, shorter telomere length (TL) has been reported in association with both CLD and HIV. As little is known in children, our objective was to compare TL in HIV-positive (cART-naive or -treated) and HIV-negative children with and without CLD. METHODS: Participants included Zimbabwean C-PHIV, aged 6-16, who were either newly diagnosed and cART-naive, or on cART for >6 months, and HIV-negative controls of similar age and sex. Packed blood cell (granulocyte) TLs from 621 children were compared cross-sectionally between groups. For a subset of newly diagnosed C-PHIV, changes in TL following cART initiation were evaluated. RESULTS: C-PHIV had shorter granulocyte TL compared with uninfected peers, regardless of cART. Among 255 C-PHIV without CLD, TL was shorter in cART-naive participants. In multivariable analyses adjusted for age, sex, CLD, and HIV/cART status, shorter TL was independently associated with older age, being HIV positive, and having reduced forced vital capacity (FVC). Last, cART initiation increased TL. CONCLUSIONS: In this cohort, C-PHIV and those with reduced FVC have shorter granulocyte TL, possibly the result of increased immune activation and cellular turnover due to longstanding HIV infection with delayed cART initiation.

Cytomegalovirus-Specific Immunoglobulin G Is Associated With Chronic Lung Disease in Children and Adolescents from Sub-Saharan Africa Living With Perinatal Human Immunodeficiency Virus.

In a cross-sectional study of 296 children and adolescents from Zimbabwe living with perinatal human immunodeficiency virus, individuals with the top tertile of cytomegalovirus-specific immunoglobulin G titer had an increased odds of chronic lung disease (odds ratio, 3.33; 95% confidence interval, 1.37-8.85; P = .010).

Role of antenatal plasma cytomegalovirus DNA levels on pregnancy outcome and HIV-1 vertical transmission among mothers in the University of Zimbabwe birth cohort study (UZBCS).

INTRODUCTION: Despite being a leading infectious cause of childhood disability globally, testing for cytomegalovirus (CMV) infections in pregnancy is generally not done in Sub-Sahara Africa (SSA), where breastfeeding practice is almost universal. Whilst CMV and human immunodeficiency virus (HIV) are both endemic in SSA, the relationship between antenatal plasma CMV-DNA, HIV-1-RNA levels and HIV-1-mother to child transmission (MTCT) including pregnancy outcomes remains poorly described. METHODS: Pregnant women at least 20 weeks' gestational age at enrolment were recruited from relatively poor high-density suburbs in Harare, Zimbabwe. Mother-infant dyads were followed up until 6 months postpartum. In a case-control study design, we tested antenatal plasma CMV-DNA levels in all 11 HIV-1 transmitting mothers, as well as randomly selected HIV-infected but non-transmitting mothers and HIV-uninfected controls. CMV-DNA was detected and quantified using polymerase chain reaction (PCR) technique. Antenatal plasma HIV-1-RNA load was quantified by reverse transcriptase PCR. Infants' HIV-1 infection was detected using qualitative proviral DNA-PCR. Predictive value of antenatal plasma CMV-DNAemia (CMV-DNA of > 50 copies/mL) for HIV-1-MTCT was analyzed in univariate and multivariate regression analyses. Associations of CMV-DNAemia with HIV-1-RNA levels and pregnancy outcomes were also explored. RESULTS: CMV-DNAemia data were available for 11 HIV-1 transmitting mothers, 120 HIV-infected but non-transmitting controls and 46 HIV-uninfected mothers. In a multivariate logistic regression model, we found a significant association between CMV-DNAemia of > 50 copies/mL and HIV-1 vertical transmission (p = 0.035). There was no difference in frequencies of detectable CMV-DNAemia between HIV-infected and -uninfected pregnant women (p = 0.841). However, CMV-DNA levels were higher in immunosuppressed HIV-infected pregnant women, CD4 < 200 cells/µL (p = 0.018). Non-significant associations of more preterm births (< 37 weeks, p = 0.063), and generally lower birth weights (< 2500 g, p = 0.450) were observed in infants born of HIV-infected mothers with CMV-DNAemia. Furthermore, in a multivariate analysis of HIV-infected but non-transmitting mothers, CMV-DNAemia of > 50 copies/mL correlated significantly with antenatal plasma HIV-1-RNA load (p = 0.002). CONCLUSION: Antenatal plasma CMV-DNA of > 50 copies/mL may be an independent risk factor for HIV-1-MTCT and higher plasma HIV-1-RNA load, raising the possibility that controlling antenatal CMV-DNAemia might improve infant health outcomes. Further studies with larger sample sizes are warranted to confirm our findings.

Unexpectedly High Prevalence of Cytomegalovirus DNAemia in Older Children and Adolescents With Perinatally Acquired Human Immunodeficiency Virus Infection.

BACKGROUND: Older children and adolescents with perinatally acquired human immunodeficiency virus (PHIV) infection in Africa experience multiple comorbidities that are not typical of HIV-associated opportunistic infections, including growth impairment and chronic lung disease. We examined associations between plasma cytomegalovirus (CMV) DNA and lung function and growth. METHODS: Plasma CMV DNA loads were measured children aged 6-16 years with PHIV (n = 402) and HIV-uninfected controls (n = 224). The HIV-infected children were either newly diagnosed or known HIV infected and stable on antiretroviral therapy (ART) for >6 months. CMV DNA loads were measured using quantitative polymerase chain reaction. CMV DNAemia was modeled as a time-varying outcome using longitudinal mixed-effects logistic regression. RESULTS: At enrollment, CMV DNAemia ≥1000 copies/mL (defined as "clinically significant") was detected in 5.8% of uninfected children, 14.7% of HIV-infected participants stable on ART, and 22.6% of HIV-infected ART-naive children (χ2 = 23.8, P < .001). The prevalence of CMV DNAemia ≥1000 copies/mL was associated with CD4 counts <350 cells/µL. Among HIV-infected ART-naive children, the presence of CMV DNAemia of ≥1000 copies/mL was independently associated with reduced lung function (adjusted odds ratio [aOR] = 3.23; 95% confidence interval [CI], 1.23-8.46; P = .017). Among ART-treated children, stunting was associated with CMV DNAemia of ≥1000 copies/mL (aOR = 2.79; 95% CI, 0.97-8.02; P = .057). CONCLUSIONS: Clinically significant levels of CMV DNAemia were common in older children with PHIV, even those on ART, suggesting a role for inadequately controlled CMV infection in the pathogenesis of PHIV comorbidities in Africa.

Correlates of T-cell-mediated viral control and phenotype of CD8(+) T cells in HIV-2, a naturally contained human retroviral infection.

While a significant proportion of HIV-2-infected individuals are asymptomatic and maintain undetectable viral loads (controllers), 15% to 20% progress to AIDS and are predicted by detectable viremia. Identifying immune correlates that distinguish these 2 groups should provide insights into how a potentially pathogenic retrovirus can be naturally controlled. We performed a detailed study of HIV-2-specific cellular responses in a unique community cohort in Guinea-Bissau followed for over 2 decades. T-cell responses were compared between controllers (n = 33) and viremic subjects (n = 27) using overlapping peptides, major histocompatibility complex class I tetramers, and multiparameter flow cytometry. HIV-2 viral control was significantly associated with a high-magnitude, polyfunctional Gag-specific CD8(+) T-cell response but not with greater perforin upregulation. This potentially protective HIV-2-specific response is surprisingly narrow. HIV-2 Gag-specific CD8(+) T cells are at an earlier stage of differentiation than cytomegalovirus-specific CD8(+) T-cells, do not contain high levels of cytolytic markers, and exhibit low levels of activation and proliferation, representing distinct properties from CD8(+) T cells associated with HIV-1 control. These data reveal the potential T-cell correlates of HIV-2 control and the detailed phenotype of virus-specific CD8(+) T cells in a naturally contained retroviral infection.

"The effect of 48-weeks azithromycin therapy on levels of soluble biomarkers associated with HIV-associated chronic lung disease".

OBJECTIVES: HIV-associated immune activation contributes to chronic lung disease (CLD) in children and adolescents living with HIV. Azithromycin has immunomodulatory and anti-microbial properties that may be useful for treating HIV-associated CLD (HCLD). This study describes the effect of azithromycin on expression of plasma soluble biomarkers in children and adolescents with HCLD. METHODS: This study was nested within a multi-site double-blind, placebo controlled, randomised controlled trial (RCT) of azithromycin in individuals aged 6-19 years with HCLD (defined as FEV1 z-score < -1) in Malawi and Zimbabwe (BREATHE (NCT02426112)). Participants were randomized 1:1 to once-weekly oral azithromycin with weight-based dosing, for 48 weeks, or placebo. Twenty-six plasma soluble biomarkers were measured on a MagPix Luminex instrument at enrolment, after 48-weeks of treatment and 24-weeks after treatment cessation. Mixed effects models were constructed to compare biomarker expression across treatment and placebo groups. RESULTS: Weekly azithromycin was associated with reduced levels of C-Reactive Protein (CRP), E-Selectin, Matrix metalloproteinase 10 (MMP-10). Treatment effects for all soluble biomarkers were not sustained 24-weeks after treatment cessation with biomarker expression returning to pre-treatment levels. CONCLUSIONS: We observed real-world effects of azithromycin on acute inflammation, neutrophil accumulation, and extracellular matrix degradation, that were not sustained after treatment cessation. These results are pertinent when using azithromycin for its immunomodulatory properties, or targeting pathways represented by the soluble biomarkers in this study.

Proinflammatory and cardiovascular biomarkers are associated with echocardiographic abnormalities in children with HIV taking antiretroviral therapy.

OBJECTIVES: Children with perinatally acquired HIV (PHIV) and taking antiretroviral therapy (ART) have a high prevalence of subclinical cardiac disease. We hypothesized that cardiac disease may be a consequence of dysregulated systemic immune activation driven by HIV infection. We examined cardiovascular and proinflammatory biomarkers and their association with echocardiographic abnormalities in children with PHIV. DESIGN: Cross-sectional analysis of soluble biomarkers from a prospective cohort of children aged 6-16 years with PHIV and age-matched HIV-uninfected comparison group. METHODS: Cryopreserved plasma samples were used to measure seven soluble biomarkers using multiplex bead assay (Luminex). Multivariable logistic regression assessed how biomarker levels related to cardiac abnormalities. RESULTS: A total of 406 children participated in this study (195 PHIV and 211 HIV-uninfected). Mean [standard deviation (SD)] ages of PHIV and HIV-uninfected participants were 10.7 (2.6) and 10.8 (2.8) years, respectively. Plasma levels of CRP, TNF-α, ST2, VCAM-1 and GDF-15 were significantly higher in the PHIV group compared with uninfected control ( P  < 0.001). Among children with PHIV, with one-unit representing one SD in biomarker level, a one-unit increase in CRP and GDF-15, was associated with increased odds of having left ventricular (LV) diastolic dysfunction [adjusted odds ratio (aOR), 1.49 (1.02-2.18; P  < 0.040)] and [aOR 1.71 (1.18-2.53; P  = 0.006)], respectively. Each one unit increase in GDF-15 was associated with increased odds of LV hypertrophy [aOR 1.84 (95% CI 1.10-3.10; P  < 0.021)]. CONCLUSION: Children with PHIV had higher levels of proinflammatory and cardiovascular biomarkers compared with HIV-uninfected children. Increased CRP and GDF-15 were associated with cardiac abnormalities in children with PHIV.

Highly avid, oligoclonal, early-differentiated antigen-specific CD8+ T cells in chronic HIV-2 infection.

HIV-1-specific CD8(+) T cells are present in most HIV-1-infected people and play an important role in controlling viral replication, but the characteristics of an effective HIV-specific T-cell response are largely unknown. The majority of HIV-2-infected people behave as long-term non-progressors while those who progress to AIDS do so in a manner indistinguishable from HIV-1. A detailed study of HIV-2 infection may identify protective immune responses. Robust gag p26-specific T-cell responses are elicited during HIV-2 infection and correlate with control of viremia. In this study, we analyzed features of an HLA-B 3501-restricted T-cell response to HIV-2 p26 that may contribute to virus control. In contrast to HIV-1, HIV-2-specific T cells are at an early stage of differentiation (CD27(+)CD28(+)), a finding that relates directly to CD4(+) T-cell levels and inversely to immune activation. The cells demonstrate IFN-gamma secretion, oligoclonal T-cell receptor Vbeta gene segment usage, exceptional avidity and secretion of pro-inflammatory cytokines. Despite the potentially strong selection pressure imposed on the virus by these cells, there was no evidence of HIV-2 sequence evolution. We propose that in chronic HIV-2 infection, the maintenance of early-differentiated, highly avid CD8(+) T cells could account for the non-progressive course of disease. Such responses may be desirable from an HIV vaccine.

Influence of HLA class I and HLA-KIR compound genotypes on HIV-2 infection and markers of disease progression in a Manjako community in West Africa.

Overall, the time to AIDS after HIV-2 infection is longer than with HIV-1, and many individuals infected with HIV-2 virus remain healthy throughout their lives. Multiple HLA and KIR gene products have been implicated in the control of HIV-1, but the effect of variation at these loci on HIV-2 disease is unknown. We show here for the first time that HLA-B*1503 is associated significantly with poor prognosis after HIV-2 infection and that HLA-B*0801 is associated with susceptibility to infection. Interestingly, previous data indicate that HLA-B*1503 is associated with low viral loads in HIV-1 clade B infection but has no significant effect on viral load in clade C infection. In general, alleles strongly associated with HIV-1 disease showed no effect in HIV-2 disease. These data emphasize the unique nature of the effects of HLA and HLA/KIR combinations on HIV-2 immune responses relative to HIV-1, which could be related to their distinct clinical course.

Soluble biomarkers associated with chronic lung disease in older children and adolescents with perinatal HIV infection.

OBJECTIVE: HIV-associated chronic lung disease (HCLD) is a common comorbidity in children and adolescents in sub-Saharan Africa (SSA). The pathogenesis of HCLD is unclear and may be driven by underlying dysregulated systemic immune activation and inflammation. We investigated the association between 26 plasma soluble biomarkers and HCLD. DESIGN: Case--control analysis of baseline biomarker data from 336 children and adolescents (6-19 years old) with perinatal HIV infection (PHIV) and HCLD (cases) and 74 age-matched and sex-matched controls with PHIV but no CLD. HCLD was defined as having a forced expiratory volume in one second (FEV1) z score less than -1 with no reversibility. METHODS: Cryopreserved plasma collected at recruitment was used in a multiplex bead assay (Luminex) to measure baseline levels of soluble biomarkers. Logistic regression alongside data-reduction and techniques quantifying the interconnectedness of biomarkers were used to identify biomarkers associated with odds of HCLD. RESULTS: Biomarkers of general immune activation and inflammation (ß2M, CRP, sCCL5, GCSF, IFN-γ, IP-10), T-cell activation (sCD25, sCD27), platelet activation (sCD40-L), monocyte activation (sCD14), coagulation (D-Dimer), cellular adhesion (E-selectin), and extracellular matrix degradation (MMP-1, MMP-7, MMP-10) were associated with increased odds of HCLD. Exploratory PCA and assessment of biomarker interconnectedness identified T-cell and platelet activation as centrally important to this association. CONCLUSION: HCLD was associated with a large number of soluble biomarkers representing a range of different pathways. Our findings suggest a prominent role for T-cell and platelet activation in HCLD.

TRIM22 genotype is not associated with markers of disease progression in children with HIV-1 infection.

OBJECTIVE: Untreated perinatal HIV-1 infection is often associated with rapid disease progression in children with HIV (CWH), characterized by high viral loads and early mortality. TRIM22 is a host restriction factor, which directly inhibits HIV-1 transcription, and its genotype variation is associated with disease progression in adults. We tested the hypothesis that TRIM22 genotype is associated with disease progression in CWH. DESIGN: ART-naive CWH, aged 6-16 years, were recruited from primary care clinics in Harare, Zimbabwe. We performed a candidate gene association study of TRIM22 genotype and haplotypes with markers of disease progression and indicators of advanced disease. METHODS: TRIM22 exons three and four were sequenced by Sanger sequencing and single nucleotide polymorphisms were associated with markers of disease progression (CD4+ T-cell count and HIV viral load) and clinical indicators of advanced HIV disease (presence of stunting and chronic diarrhoea). Associations were tested using multivariate linear and logistic regression models. RESULTS: A total of 241 children, median age 11.4 years, 50% female, were included. Stunting was present in 16% of participants. Five SNPs were analyzed including rs7935564, rs2291842, rs78484876, rs1063303 and rs61735273. The median CD4+ count was 342 (IQR: 195-533) cells/µl and median HIV-1 viral load 34 199 (IQR: 8211-90 662) IU/ml. TRIM22 genotype and haplotypes were not associated with CD4+ T-cell count, HIV-1 viral load, stunting or chronic diarrhoea. CONCLUSION: TRIM22 genotype was not associated with markers of HIV disease progression markers or advanced disease in CWH.

Robust Gag-specific T cell responses characterize viremia control in HIV-2 infection.

HIV-2 infection in the majority of infected subjects follows an attenuated disease course that distinguishes it from infection with HIV-1. Antigen-specific T cells are pivotal in the management of chronic viral infections but are not sufficient to control viral replication in HIV-1-positive subjects, and their function in HIV-2 infection is not fully established. In a community-based cohort of HIV-2 long-term nonprogressors in rural Guinea-Bissau, we performed what we believe is the first comprehensive analysis of HIV-2-specific immune responses. We demonstrate that Gag is the most immunogenic protein. The magnitude of the IFN-gamma immune response to the HIV-2 proteome was inversely correlated with HIV-2 viremia, and this relationship was specifically due to the targeting of Gag. Furthermore, patients with undetectable viremia had greater Gag-specific responses compared with patients with high viral replication. The most frequently recognized peptides clustered within a defined region of Gag, and responses to a single peptide in this region were associated with low viral burden. The consistent relationship between Gag-specific immune responses and viremia control suggests that T cell responses are vital in determining the superior outcome of HIV-2 infection. A better understanding of how HIV-2 infection is controlled may identify correlates of effective protective immunity essential for the design of HIV vaccines.

A novel full-length two-domain KIR2DL5A allele isolated in Zimbabwean samples: KIR2DL5A*0010104.

The novel allele KIR2DL5A*0010104 differs from that of KIR2DL5A*0010101 with eight single intronic nucleotide changes.

Variation of HLA class I (-A and -C) genes in individuals infected with hepatitis B or hepatitis C virus in Cameroon.

The Human Leucocyte Antigens (HLA) work in concert with other immune factors to modulate immunity to viral infections. Extensive variation has been reported in the genetic sequences and functions of classical HLA class I genes in many (mostly Western) populations, and several HLA associations with infectious disease outcomes have been reported. Little is known about their role in the susceptibility or resistance to hepatitis viruses in Central African populations. The aim of this study was to determine variants of two HLA class I genes (HLA-A and -C) in adults infected with hepatitis B (HBV)- or -C (HCV) virus in Cameroon. In this case-control study, a total of 169 unrelated adults comprising 68 HCV-infected, 38 HBV-infected and 63 uninfected (controls) individuals participated. Each consented participant was screened for HBV, HCV, and HIV infections and willingly donated a single blood sample for genomic DNA isolation and some clinical laboratory tests. HLA-A and HLA-C were genotyped using previously described sequence-based techniques (SBT). A total of 54 HLA alleles were identified in the study population (27 HLA-A and 27 HLA-C). HLA-A∗23:01 and HLA-C∗07:01 were the most common alleles with genotype frequencies of 31.4% and 29.3%, respectively. Hepatitis individuals were six times more likely to be HLA-A∗30:01 carriers than uninfected controls (OR = 6.30, p = 0.020 (HBV); OR = 6.21, p = 0.010 (HCV), respectively). Similarly, carriers of HLA-C∗17:01 were over-represented in the HBV-infected compared to the uninfected control group (21.9% vs. 6.4%, respectively) suggesting that this allele could play a role in the susceptibility to HBV infection. These findings demonstrate that carriers of HLA-A∗30:01 were over-represented in the hepatitis group compared to uninfected controls while HLA-C∗17:01 was completely absent in the HCV + group.

Killer Cell Immunoglobulin-Like Receptor Genotypes and Haplotypes Contribute to Susceptibility to Hepatitis B Virus and Hepatitis C Virus Infection in Cameroon.

Over 325 million people worldwide are living with hepatitis B and C viral infections and are at greater risk of developing hepatocellular carcinoma. The interactions between killer cell immunoglobulin-like receptors (KIRs) and their cognate ligands, human leukocyte antigens, modulate both infection processes and disease progression. We report here (1) genotype and haplotype variations in KIR genes in Cameroon and (2) their impact on susceptibility to hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. In 98 unrelated individuals (33 HCV+, 31 HBV+, and 34 uninfected healthy controls), we determined the presence of 15 KIR genes by polymerase chain reaction-sequence-specific primer techniques. One pseudogene and all 14 KIR genes were present. We identified 36 KIR genotypes, 5 of which have not been previously reported in public databases. Two inhibitory (KIR2DL1 and KIR2DL3) and three activating (KIR2DS4, KIR2DS2, and KIR2DS3) genes were present in all HCV-infected individuals. Similarly, KIR3DL1, KIR2DL1, and KIR2DS4 were present at 100% in the HBV+ group. Compared with uninfected healthy controls, the frequencies of KIR2DL2 and KIR3DS1 were significantly lower in the HBV+ group (p = 0.003 and p < 0.001, respectively). Conversely, KIR3DS1 was significantly overrepresented in the HCV+ group compared with controls (97.0% vs. 64.7%, respectively, p < 0.001). These results may imply that KIR3DS1 carriers were less likely to be HBV infected, but may be predisposed to HCV infection compared with uninfected controls, indicating their important role in transmission of these viruses. However, phenotypic, functional, and genomic studies to elucidate the role of these KIR genotypes and haplotypes in infection with HBV and HCV are important.

KIR and HLA-C Genetic Polymorphisms Influence Plasma IP-10 Concentration in Antiretroviral Therapy-Naive HIV-Infected Adult Zimbabweans.

Past studies on the relationship between Killer cell Immunoglobulin-like Receptor (KIR) and Human Leukocyte Antigen (HLA) genetic variation and chronic immune activation (CIA) in HIV infection are not uniformly consistent. Moreover, interferon-γ-induced protein 10 (IP-10) is a soluble biomarker of immune activation, with high plasma concentrations predicting accelerated disease progression in HIV infection. Thus, we investigated the association of KIR and HLA-C genetic polymorphisms with plasma IP-10 concentration in 183 treatment-naive chronically HIV-infected adults of Bantu origin from Zimbabwe. KIR genetic variation was determined using allele-specific primer PCR while HLA-C typing was characterized by sequencing. Plasma IP-10 was quantified using enzyme-linked immunosorbent assay. The KIR2DL3 gene was significantly associated with CIA as observed from IP-10 concentrations among KIR2DL3 carriers (265.20 pg/mL, IQR: 179.99-385.19) compared with KIR2DL3 noncarriers (183.56 pg/mL; IQR: 110.98-230.81; p = 0.001) and among KIR2DL3+HLA-C2 carriers (226.23 pg/mL, IQR: 187.96-394.73) compared with KIR2DL3+HLA-C2 noncarriers (212.86 pg/mL, IQR: 160.15-344.99; p = 0.017), respectively. Similarly, IP-10 concentrations were significantly higher (p = 0.030) in the KIR3DS1 carriers (313.86 pg/mL, IQR: 230.05-469.20) compared with KIR3DS1 noncarriers (246.01 pg/mL, IQR: 169.58-373.32). Thus, KIR and HLA-C could be playing important roles in HIV-associated immune activation. The elevation of IP-10 in KIR2DL3 and KIR2DL3+C2 could potentially be explained by increased IFN-γ secretion from activated NK cell activation due to the absence of KIR2DL3's cognate C1 ligand. To the best of our knowledge, this is the first study on a potential link between KIR and HLA-C genetic determinants and plasma IP-10 concentration in this population sample. Future studies are called for in other world populations for biomarkers of disease progression and mechanisms of IP-10 variability in HIV infection.

Discrimination Between Human Leukocyte Antigen Class I-Bound and Co-Purified HIV-Derived Peptides in Immunopeptidomics Workflows.

Elucidation of novel peptides presented by human leukocyte antigen (HLA) class I alleles by immunopeptidomics constitutes a powerful approach that can inform the rational design of CD8+ T cell inducing vaccines to control infection with pathogens such as human immunodeficiency virus type 1 (HIV-1) or to combat tumors. Recent advances in the sensitivity of liquid chromatography tandem mass spectrometry instrumentation have facilitated the discovery of thousands of natural HLA-restricted peptides in a single measurement. However, the extent of contamination of class I-bound peptides identified using HLA immunoprecipitation (IP)-based immunopeptidomics approaches with peptides from other sources has not previously been evaluated in depth. Here, we investigated the specificity of the IP-based immunopeptidomics methodology using HLA class I- or II-deficient cell lines and membrane protein-specific antibody IPs. We demonstrate that the 721.221 B lymphoblastoid cell line, widely regarded to be HLA class Ia-deficient, actually expresses and presents peptides on HLA-C*01:02. Using this cell line and the C8166 (HLA class I- and II-expressing) cell line, we show that some HLA class II-bound peptides were co-purified non-specifically during HLA class I and membrane protein IPs. Furthermore, IPs of "irrelevant" membrane proteins from HIV-1-infected HLA class I- and/or II-expressing cells revealed that unusually long HIV-1-derived peptides previously reported by us and other immunopeptidomics studies as potentially novel CD8+ T cell epitopes were non-specifically co-isolated, and so constitute a source of contamination in HLA class I IPs. For example, a 16-mer (FLGKIWPSYKGRPGNF), which was detected in all samples studied represents the full p1 segment of the abundant intracellular or virion-associated proteolytically-processed HIV-1 Gag protein. This result is of importance, as these long co-purified HIV-1 Gag peptides may not elicit CD8+ T cell responses when incorporated into candidate vaccines. These results have wider implications for HLA epitope discovery from abundant or membrane-associated antigens by immunopeptidomics in the context of infectious diseases, cancer, and autoimmunity.