Abstract The vagina and cervix have the lowest biodiversity of the human microbiota, with a colonized epithelium dominated by protective Lactobacilli. Changes in the cervicovaginal microbes are therefore a predicted cause of malignancies, revealing a tremendous potential of microbiome-related processes to be used in early cancer diagnostics. We hypothesized that bacterial communities and their metabolic profiles change in association to HPV infections, BMI and cervical disease. We characterized the microbiota and the metabolomic profiles of 47 Puerto Rican women coming to San Juan OB/Gyn clinics using 16S rRNA sequencing and Gas Chromatography coupled to Mass Spectrometry respectively. Samples compared between those negative for intraepithelial lesion or malignancy (NILM) and high-grade squamous intraepithelial lesions (HGSIL) samples, and grouped according to HPV status (positive and negative) followed by body mass indexes (BMI) of normal weight (NW) and overweight (OW). The microbiota was analyzed at first with Qiita, using the greengenes database as taxonomic reference, and community analyses were performed in QIIME and R. The MIMOSA2 framework was the approach to identify the key species contributors to the metabolite concentrations and their correspondent producing enzymes annotated using KEGG database. After that, we applied BURRITO framework to pair taxonomic and functional information obtained by MIMOSA2.The analysis of NILM (HPV+ and NW) and NILM (HPV+ and OW) showed a strong influence of HPV infections on microbiome contributions to metabolic shifts related to amino acid metabolism, and they were not overlapped in the metabolite identities and functions. In particular, degradation of alanine and synthesis of alanyl-tRNAAla concomitant with the activity of alanyl-tRNA synthetase which was associated primarily with A. vaginae, Gardnerella, L. inners and to a lesser extent by L. crispatus. Simultaneously, A. vaginae and Gardnerella displayed an antagonistic relationship for alanine production, associated with cysteine desulfurase. NILM HPV positive groups displayed enrichments in metabolites that belong to the tryptophan catabolic pathway. The HGSIL (HPV+ and OW) group triggered the most complex metabolic shift attributed to pyruvate, purine metabolism, glycine, serine and threonine metabolism, and aminoacyl-tRNA biosynthesis. Taken together, our data suggest that HPV infections trigger different changes in the dynamic equilibrium of the cervical lavage microbiota at the compositional and functional levels. These changes alter the metabolic phenotype of the host and are strongly associated with BMI. Sponsored by PRSTRT ARG# 2020-00112; NIGMS P20596GM103475, NIMHD S21MD001830. Citation Format: Natalyia Chorna, Josefina Romaguera, Filipa Godoy-Vitorino. Contributions of the rare microbial biosphere, HPV infections and BMI to shifts in metabolic profiles in the cervical lavage of Hispanics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2913.