Systematic analysis of Kaposi's sarcoma (KS)-associated herpesvirus genomes from a KS case-control study in Cameroon: Evidence of dual infections but no association between viral sequence variation and KS risk.

In sub-Saharan Africa, Kaposi's sarcoma-associated herpesvirus (KSHV) is endemic, and Kaposi's sarcoma (KS) is a significant public health problem. Until recently, KSHV genotype analysis was performed using variable gene regions, representing a small fraction of the genome, and thus the contribution of sequence variation to viral transmission or pathogenesis are understudied. We performed near full-length KSHV genome sequence analysis on samples from 43 individuals selected from a large Cameroonian KS case-control study. KSHV genomes were obtained from 21 KS patients and 22 control participants. Phylogenetic analysis of the K1 region indicated the majority of sequences were A5 or B1 subtypes and all three K15 alleles were represented. Unique polymorphisms in the KSHV genome were observed including large gene deletions. We found evidence of multiple distinct KSHV genotypes in three individuals. Additionally, our analyses indicate that recombination is prevalent suggesting that multiple KSHV infections may not be uncommon overall. Most importantly, a detailed analysis of KSHV genomes from KS patients and control participants did not find a correlation between viral sequence variations and disease. Our study is the first to systematically compare near full-length KSHV genome sequences between KS cases and controls in the same endemic region to identify possible sequence variations associated with disease risk.

Distinct genetic architectures and environmental factors associate with host response to the γ2-herpesvirus infections.

Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr Virus (EBV) establish life-long infections and are associated with malignancies. Striking geographic variation in incidence and the fact that virus alone is insufficient to cause disease, suggests other co-factors are involved. Here we present epidemiological analysis and genome-wide association study (GWAS) in 4365 individuals from an African population cohort, to assess the influence of host genetic and non-genetic factors on virus antibody responses. EBV/KSHV co-infection (OR = 5.71(1.58-7.12)), HIV positivity (OR = 2.22(1.32-3.73)) and living in a more rural area (OR = 1.38(1.01-1.89)) are strongly associated with immunogenicity. GWAS reveals associations with KSHV antibody response in the HLA-B/C region (p = 6.64 × 10-09). For EBV, associations are identified for VCA (rs71542439, p = 1.15 × 10-12). Human leucocyte antigen (HLA) and trans-ancestry fine-mapping substantiate that distinct variants in HLA-DQA1 (p = 5.24 × 10-44) are driving associations for EBNA-1 in Africa. This study highlights complex interactions between KSHV and EBV, in addition to distinct genetic architectures resulting in important differences in pathogenesis and transmission.

Dual infection and recombination of Kaposi sarcoma herpesvirus revealed by whole-genome sequence analysis of effusion samples.

Kaposi sarcoma herpesvirus (KSHV) is the etiological agent of three malignancies, Kaposi sarcoma (KS), primary effusion lymphoma (PEL) and KSHV-associated multicentric Castelman disease. KSHV infected patients may also have an interleukin six-related KSHV-associated inflammatory cytokine syndrome. KSHV-associated diseases occur in only a minority of chronically KSHV-infected individuals and often in the setting of immunosuppression. Mechanisms by which KSHV genomic variations and systemic co-infections may affect the pathogenic pathways potentially leading to these diseases have not been well characterized in vivo. To date, the majority of comparative genetic analyses of KSHV have been focused on a few regions scattered across the viral genome. We used next-generation sequencing techniques to investigate the taxonomic groupings of viruses from malignant effusion samples from fourteen participants with advanced KSHV-related malignancies, including twelve with PEL and two with KS and elevated KSHV viral load in effusions. The genomic diversity and evolutionary characteristics of nine isolated, near full-length KSHV genomes revealed extensive evidence of mosaic patterns across all these genomes. Further, our comprehensive NGS analysis allowed the identification of two distinct KSHV genome sequences in one individual, consistent with a dual infection. Overall, our results provide significant evidence for the contribution of KSHV phylogenomics to the origin of KSHV subtypes. This report points to a wider scope of studies to establish genome-wide patterns of sequence diversity and define the possible pathogenic role of sequence variations in KSHV-infected individuals.

Relationship between human leukocyte antigen alleles and risk of Kaposi's sarcoma in Cameroon.

Several studies published to date report associations between human leukocyte antigen (HLA) alleles and different types of Kaposi's Sarcoma (KS). However, there is little concordance between the HLA alleles identified and the populations studied. To test whether HLA alleles associate with KS in a Cameroonian case-control study, we performed high-resolution HLA typing in KSHV seropositive individuals. Among HIV-positive individuals, carriers of HLA-B*14:01 were at a significantly higher risk of AIDS-KS (p = 0.033). For HIV-negative patients, a gene-wise comparison of allele frequencies identified the HLA-B (p = 0.008) and -DQA1 (p = 0.002) loci as possible risk factors for endemic KS. Our study provides additional understanding of genetic determinants of KS and their implications in disease pathogenesis. Further validation of these findings is needed to define the functional relevance of these associations.

Polymorphisms in KSHV-encoded microRNA sequences affect levels of mature viral microRNA in Kaposi Sarcoma lesions.

Background: We previously reported Kaposi sarcoma-associated herpesvirus (KSHV) microRNA sequence variants in clinical samples correlated with increased risk of multicentric Castleman's disease (MCD). We then demonstrated that microRNAs with variant sequence have different maturation and mature microRNA expression in vitro. Here, we illustrate the association between microRNA sequence and changes in mature microRNA levels within Kaposi sarcoma (KS) lesions. Methods: KSHV microRNA sequences were determined from 20 KS lesions and 4 control skin biopsies from individuals evaluated for KS. Levels of mature KSHV microRNAs were measured with 21 custom small RNA qRT-PCR assays using RNA RNU6B as endogenous control. Results: The levels of 13 KSHV-encoded microRNAs were elevated in KS lesions compared to control biopsies. MicroRNA 9-5p was strongly down regulated in South African vs. US biopsies. Low levels of K12-9-5p were associated with single nucleotide polymorphisms (SNPs) in miR-K12-9-5p, 4-5p, 5-3p, 7-3p and pri-miR-K12-3. One SNP in pri-miR-K12-3 resulted in down regulation of miR-K12-6-3p, 8-3p, 10-3p, 12-5p and the upregulation of 5-5p, illustrating sequence variants outside pre-microRNAs were also associated with changes in mature microRNA levels. Conclusions: The levels of mature KSHV-encoded microRNAs in KS lesions correlate with sequence variation reflecting changes in secondary and tertiary RNA structure.

Sensitivity of the C-Terminal Nuclease Domain of Kaposi's Sarcoma-Associated Herpesvirus ORF29 to Two Classes of Active-Site Ligands.

Kaposi's sarcoma-associated herpesvirus (KSHV), the etiological agent of Kaposi's sarcoma, belongs to the Herpesviridae family, whose members employ a multicomponent terminase to resolve nonparametric viral DNA into genome-length units prior to their packaging. Homology modeling of the ORF29 C-terminal nuclease domain (pORF29C) and bacteriophage Sf6 gp2 have suggested an active site clustered with four acidic residues, D476, E550, D661, and D662, that collectively sequester the catalytic divalent metal (Mn2+) and also provided important insight into a potential inhibitor binding mode. Using this model, we have expressed, purified, and characterized the wild-type pORF29C and variants with substitutions at the proposed active-site residues. Differential scanning calorimetry demonstrated divalent metal-induced stabilization of wild-type (WT) and D661A pORF29C, consistent with which these two enzymes exhibited Mn2+-dependent nuclease activity, although the latter mutant was significantly impaired. Thermal stability of WT and D661A pORF29C was also enhanced by binding of an α-hydroxytropolone (α-HT) inhibitor shown to replace divalent metal at the active site. For the remaining mutants, thermal stability was unaffected by divalent metal or α-HT binding, supporting their role in catalysis. pORF29C nuclease activity was also inhibited by two classes of small molecules reported to inhibit HIV RNase H and integrase, both of which belong to the superfamily of nucleotidyltransferases. Finally, α-HT inhibition of KSHV replication suggests ORF29 nuclease function as an antiviral target that could be combined with latency-activating compounds as a shock-and-kill antiviral strategy.

T-cell responses to KSHV infection: a systematic approach.

Prior studies of T-cell responses to KSHV have included relatively few participants and focused on relatively few KSHV antigens. To provide a more comprehensive analysis, we investigated T-cell responses to the whole KSHV proteome using IFN-γ ELISpot. Using ∼7,500 overlapping 15mer peptides we generated one to three peptide pools for each of the 82 KSHV ORFs. IFN-γ ELISpot analysis of PBMCs from 19 patients with a history of KSHV-associated disease and 24 healthy donors (11 KSHV seropositive) detected widely varied responses. Fifty six of the 82 ORFs were recognized by at least one individual but there was little overlap between participants. Responses to at least one ORF pool were observed in all 19 patients and in 7 seropositive donors. Four seropositive donors and 10 seronegative donors had no detectable responses while 3 seronegative donors had weak responses to one ORF. Patients recognised more ORFs than the donors (p=0.04) but the response intensity (spot forming units: SFU per million cells) was similar in the two groups. In four of the responding donors, individual peptides eliciting the predominant responses were identified: three donors responded to only one peptide per ORF, while one recognized five. Using intracellular cytokine staining in four participant samples, we detected peptide-induced IFN-γ, MIP1-ß, and TNF-α as well as CD107a degranulation, consistent with multifunctional effector responses in CD8+ and CD4+ T cells. Sequence analysis of TCRs present in peptide specific T-cell clones generated from two participants showed both mono- and multi-clonotypic responses. Finally, we molecularly cloned the KSHV specific TCRs and incorporated the sequences into retroviral vectors to transfer the specificities to fresh donor cells for additional studies. This study suggests that KSHV infected individuals respond to diverse KSHV antigens, consistent with a lack of shared immunodominance and establishes useful tools to facilitate KSHV immunology studies.

HLA-allelotype associations with nevirapine-induced hypersensitivity reactions and hepatotoxicity: a systematic review of the literature and meta-analysis.

OBJECTIVE: Various studies have investigated associations between immunogenetic (HLA-allelotypes) factors and the risk of nevirapine-induced hypersensitivity reactions. However, results from individual studies have been inconsistent. To evaluate the association between HLA alleles and nevirapine hypersensitivity, a systematic review and meta-analysis was carried out. METHODS: A literature review of articles published up to December 2014 was performed. Where both allelotype and phenotype data from two or more studies could be combined, a Mantel-Haenszel random effects model was used to obtain a pooled odds ratio (OR) and 95% confidence intervals (CIs). RESULTS: Thirteen case-control studies investigating nevirapine hypersensitivity and HLA-allelotypes were identified. The OR (95% CI) for HLA-B*35 and cutaneous adverse drug reactions (cADRs) was 2.45 (95% CI: 1.10-5.48), with significant heterogeneity (I²=69%). The association between HLA-B*58:01 and hepatotoxicity in black African patients showed an OR of 3.51 (95% CI: 1.72-7.19) with no between study heterogeneity (I²=0%). For HLA-C*04 carriage, the OR in four different ethnic populations for cADRs was 2.63 (95% CI: 1.97-3.52; I²=0%). The OR for carriage of HLA-DRB1*01 in a multiethnic cohort was 2.94 (95% CI: 1.92-4.50; I²=0%) for nevirapine hepatotoxicity. CONCLUSION: HLA-C*04 carriage may be a common risk factor for cADRs to nevirapine in populations of differing ethnicity, whereas HLA-B*35 and HLA-DRB1*01 appear to be driven predominantly by an association within Thai and White populations, respectively. Heterogeneity between studies could be reduced by undertaking an individual patient data meta-analysis allowing the standardization of phenotype definitions and investigation of common haplotypes between populations.

CYP2B6 c.983T>C polymorphism is associated with nevirapine hypersensitivity in Malawian and Ugandan HIV populations.

BACKGROUND: Nevirapine, an NNRTI used in HIV treatment, can cause hypersensitivity reactions in 6%-10% of patients. In the most serious cases (1.3%) this can manifest as Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN). METHODS: DNA samples were obtained and analysed from a total of 209 adult patients with nevirapine hypersensitivity (57 from a prospective cohort and 152 routine clinic patients) and compared with 463 control patients on nevirapine without any hypersensitivity. The case group included 70 patients with SJS/TEN. All individuals were genotyped for two SNPs in the CYP2B6 gene [c.516G>T (CYP2B6*9) and c.983T>C (CYP2B6*18)] using the TaqMan real-time genotyping platform. The replication cohort comprised 29 controls and 55 nevirapine hypersensitive patients, including 8 SJS/TEN cases. RESULTS: An association between the CYP2B6 c.983T>C polymorphism and nevirapine-induced SJS/TEN was observed. In the SJS/TEN group, 30% of individuals possessed at least one c.983T>C versus 16% in the tolerant group [P = 0.006; OR (95% CI) 2.24 (1.27-3.94)]. This association was not significant in the replication cohort [P = 0.075; OR (95% CI) 4.33 (0.80-23.57)]. Combined analysis resulted in an OR of 2.52 (95% CI 1.48-4.20; P = 0.0005) for the association of c.983T>C with SJS/TEN. No association was observed for c.983T>C with other hypersensitivity phenotypes and for CYP2B6 c.516G>T with any hypersensitivity phenotypes. CONCLUSIONS: Our data show an association between the c.983T>C polymorphism and nevirapine-induced SJS/TEN. CYP2B6 c.983T>C has a frequency of 5%-10% in a variety of African populations, but is not observed in Caucasians, thus representing an ethnic-specific predisposing factor.

Loss of DJ-1 protein stability and cytoprotective function by Parkinson's disease-associated proline-158 deletion.

DJ-1 is a ubiquitous protein regulating cellular viability. Recessive mutations in the PARK7/DJ-1 gene are linked to Parkinson's disease (PD). Although the most dramatic L166P point mutation practically eliminates DJ-1 protein and function, the effects of other PD-linked mutations are subtler. Here, we investigated two recently described PD-associated DJ-1 point mutations, the A179T substitution and the P158Δ in-frame deletion. [A179T]DJ-1 protein was as stable as wild-type [wt]DJ-1, but the P158Δ mutant protein was less stable. In accord with the notion that dimer formation is essential for DJ-1 protein stability, [P158Δ]DJ-1 was impaired in dimer formation. Similar to our previous findings for [M26I]DJ-1, [P158Δ]DJ-1 bound aberrantly to apoptosis signal-regulating kinase 1. Thus, the PD-associated P158Δ mutation destabilizes DJ-1 protein and function. As there is also evidence for an involvement of DJ-1 in multiple system atrophy, a PD-related α-synucleinopathy characterized by oligodendroglial cytoplasmic inclusions, we studied an oligodendroglial cell line stably expressing α-synuclein. α-Synuclein aggregate dependent microtubule retraction upon co-transfection with tubulin polymerization-promoting protein p25α was ameliorated by [wt]DJ-1. In contrast, DJ-1 mutants including P158Δ failed to protect in this system, where we found evidence of apoptosis signal-regulating kinase 1 (ASK1) involvement. In conclusion, the P158Δ point mutation may contribute to neurodegeneration by protein destabilization and hence loss of DJ-1 function.

Parkinson's disease-associated DJ-1 modulates innate immunity signaling in Caenorhabditis elegans.

DJ-1 is a neuroprotective gene mutated in recessive Parkinson's disease (PD). In addition to direct protective functions in neurons, DJ-1 regulates neuroinflammatory signaling in primary mouse brain astrocytes. To assess the influence of DJ-1 on innate immunity signaling in vivo, we have generated djr-1 knockout Caenorhabditis elegans. When grown on pathogenic gram-negative bacteria, djr-1 (-/-) worms showed stronger phosphorylation of p38 mitogen-activated protein kinase (PMK-1) and hyper-induction of PMK-1 target genes. Thus, PD-associated DJ-1 contributes to regulation of innate immunity.