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IntroductionPersistent oral infections with high-risk human papillomavirus (HR-HPV) are a potential cause of most oropharyngeal cancers (OPCs). Oral HR-HPV infection and persistence are significantly higher in people living with HIV (PLWH). Most data on oral HR-HPV in PLWH come from developed countries or adult cohorts. This study aims to investigate oral HR-HPV susceptibility and persistence among children and adolescents living with HIV (CALHIV) and to understand the roles of perinatal HIV exposure, infection, antiretroviral treatment, and the oral microbiome.Methods and analysisThis prospective cohort study is ongoing at the University of Benin Teaching Hospital (UBTH), Nigeria, involving mother-child pairs followed at 6-month intervals for 2 years. Participants include children aged 9–18 and their mothers aged 18 and above. The study targets 690 adolescents in three groups: 230 CALHIV, 230 HIV-exposed but uninfected and 230 HIV-unexposed and uninfected. Oral rinse, saliva, buccal swabs and supragingival plaque samples are collected at each visit. Blood samples are tested for HIV, Hepatitis B virus (HBV) and Hepatitis C virus (HCV), with CD4, CD8 and full blood counts performed. Oral HPV is assessed for incidence, persistence, and clearance. Statistical analyses to look for associations between cohort baseline characteristics and findings will be conducted using univariable and multivariable models for repeated data and high-dimensional microbiome data. All statistical tests will be two-sided; a p value <0.05 will indicate significance. Multiple comparisons will be adjusted using the False Discovery Rate (FDR) correction to control for Type I error.Ethics and disseminationThe study was approved by Rutgers State University (Pro2022000949) and the UBTH (ADM/E22/A/VOL. VII/14813674). Informed consent was obtained from all parents/guardians.

Whole metagenome shotgun sequencing (WMS) is widely used to profile microbial function. However, technical variability in sequencing and analysis often obscures true biological patterns. Large-scale studies are particularly susceptible to batch effects, such as differences in sequencing depth and platform and annotation strategies, as well as sample-to-flow-cell assignments. However, the relative effects of these factors on functional inference in such studies have yet to be systematically evaluated.We analyzed oral-rinse WMS data from a study cohort including 671 Nigerian youths aged 9-18, sequenced on two Illumina platforms. Microbial molecular functionality encoded in these data were annotated using the mi-faser/Fusion pipeline, to capture the broad functional repertoire, and HUMAnN 3/EC numbers pipeline to characterize curated enzymatic activities. We then quantified how technical factors and batch effects shaped the recovery of microbial functionality. Three findings of our work were most salient. First, we observed that the choice of annotation strategy traded off between breadth and specificity of functional coverage. Second, we found that low-prevalence functions were disproportionately lost at shallow sequencing depths, indicating that in e.g. case-control studies with few representatives of the minor class, sequencing depth could critically impact study resolution. Finally, using our newly developed model relating sequencing depth to functional recovery, we demonstrated that increasing sequencing depth does not directly or proportionally improve functional recall. That is, at as little as 10% of this study's sequencing depth, 30% of the estimated complete microbiome functional repertoire was detectable. However, even at the full depth used in this study, we were only able to recover an estimated 60% of that complete functional repertoire. Together, these findings and our depth-to-function mapping framework provide practical guidelines for the design and interpretation of WMS studies. Coordinating sequencing depth planning with annotation strategy, experimental design, and rigorous batch control is thus essential for robust detection of microbial functions and for ensuring reproducible microbiome insights.