Epistatic interaction between ERAP2 and HLA modulates HIV-1 adaptation and disease outcome in an Australian population.

A strong genetic predictor of outcome following untreated HIV-1 infection is the carriage of specific alleles of human leukocyte antigens (HLAs) that present viral epitopes to T cells. Residual variation in outcome measures may be attributed, in part, to viral adaptation to HLA-restricted T cell responses. Variants of the endoplasmic reticulum aminopeptidases (ERAPs) influence the repertoire of T cell epitopes presented by HLA alleles as they trim pathogen-derived peptide precursors to optimal lengths for antigen presentation, along with other functions unrelated to antigen presentation. We investigated whether ERAP variants influence HLA-associated HIV-1 adaptation with demonstrable effects on overall HIV-1 disease outcome. Utilizing host and viral data of 249 West Australian individuals with HIV-1 subtype B infection, we identified a novel association between two linked ERAP2 single nucleotide polymorphisms (SNPs; rs2248374 and rs2549782) with plasma HIV RNA concentration (viral load) (P adjusted = 0.0024 for both SNPs). Greater HLA-associated HIV-1 adaptation in the HIV-1 Gag gene correlated significantly with higher viral load, lower CD4+ T cell count and proportion; P = 0.0103, P = 0.0061, P = 0.0061, respectively). When considered together, there was a significant interaction between the two ERAP2 SNPs and HLA-associated HIV-1 adaptation on viral load (P = 0.0111). In a comprehensive multivariate model, addition of ERAP2 haplotypes and HLA associated adaptation as an interaction term to known HLA and CCR5 determinants and demographic factors, increased the explanatory variance of population viral load from 17.67% to 45.1% in this dataset. These effects were not replicated in publicly available datasets with comparably sized cohorts, suggesting that any true global epistasis may be dependent on specific HLA-ERAP allelic combinations. Our data raises the possibility that ERAP2 variants may shape peptide repertoires presented to HLA class I-restricted T cells to modulate the degree of viral adaptation within individuals, in turn contributing to disease variability at the population level. Analyses of other populations and experimental studies, ideally with locally derived ERAP genotyping and HLA-specific viral adaptations are needed to elucidate this further.

Pragmatic Adaptive Trial for Respiratory Infection in Children (PATRIC) Clinical Registry protocol.

INTRODUCTION: Acute respiratory infections (ARI) are the most common cause of paediatric hospitalisation. There is an urgent need to address ongoing critical knowledge gaps in ARI management. The Pragmatic Adaptive Trial for Respiratory Infections in Children (PATRIC) Clinical Registry will evaluate current treatments and outcomes for ARI in a variety of paediatric patient groups. The registry will provide a platform and data to inform a number of PATRIC clinical trials, testing various interventions in ARI treatment and management to optimise paediatric ARI care. METHODS AND ANALYSIS: The PATRIC Clinical Registry is a single-centre, prospective observational registry recruiting from a tertiary paediatric Emergency Department in Western Australia. Through characterising demographic, clinical, treatment and outcome data, the PATRIC Clinical Registry will improve our understanding of antibiotic utilisation and ARI outcomes in children. ETHICS AND DISSEMINATION: The PATRIC Clinical Registry is conducted in accordance with the Declaration of Helsinki, and the International Council for Harmonisation (ICH) Guidelines for Good Clinical Practice (CPMP/ICH/13595) July 1996. Approval is provided by the Child and Adolescent Health Service Human Research Ethics Committee (HREC). Study results will be communicated by presentation and publication (HREC: RGS0000003078.) TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12619000903189. UTN: U1111-1231-3365.