Bacterial Dysbiosis and Epithelial Transformation of the California Sea Lion (Zalophus Californianus)

Abstract

Despite the high incidence of urogenital carcinoma (UGC) in California sea lions stranded along California, no UGC has been reported in other areas of their distribution, although cell morphologies typical of premalignant states have been found. Risk factors for UGC include high of organochlorines and infection with a gammaherpesvirus, OtHV-1, but the importance of the bacteriome for cellular epithelial transformation remains unknown. We characterized the genital bacteriome of adult female California sea lions along their distribution in the Gulf of California, and examined whether the diversity and abundance of the bacteriome varied spatially, whether there were detectable differences in the bacteriome between healthy and altered epithelia, and whether the bacteriome was different in sea lions infected with OtHV-1 or papillomavirus. We detected 2,270 ASVs in the genital samples, of which 35 met the criteria for inclusion in the core bacteriome. Fusobacteriia and Clostridia were present in all samples, at high abundances, and Actinobacteria, Alphaproteobacteria, and Campylobacteria were also well-represented. Alpha diversity and abundance of the sea lion genital bacteriome varied geographically. The abundance of bacterial ASVs varied depending on the cytological status and inflammation of the genital epithelia, with differences driven by classes Fusobacteriia, Clostridia, Campylobacteria and Alphaproteobacteria. Alpha diversity and abundance were lowest in samples in which OtHV-1 was detected, and highest those with papilomavirus. Our study is the first investigation of how the bacteriome is related to epithelial integrity in a wild marine species prone to developing cancer.

Keywords: genital bacteriome, California sea lion, Clostridia, Dysbiosis, Fusobacteriia, Oceanivirga