First molecular report of the Chelonid alphaherpesvirus 5 (ChHV5 Scutavirus chelonidalpha5) in a green turtle (Chelonia mydas) with fibropapillomatosis in the southwest Gulf of Mexico

Abstract Fibropapillomatosis (FP) is an emerging neoplastic disease associated with chelonid herpesvirus 5 (ChHV5; Scutavirus chelonidalpha 5 ) that affects all species of marine turtles worldwide, mainly green turtles ( Chelonia mydas ) at coastal feeding sites. This report describes the case of a juvenile green turtle stranded alive on the coast of Veracruz, Mexico that presented 41 lesions suggestive of FP distributed on the eyes, neck, front flippers, axillary/inguinal regions and plastron. Morphologically, the lesions varied in size, shape and appearance of the surface. A tumour was collected and analysed by histopathology revealing a benign neoplasm with fibropapilloma characteristics (dermal and epidermal proliferation) and cytopathic effects consistent with herpesvirus infection, such as ballooning, reticular, and vacuolar degeneration, cell necrosis, eosinophilic intranuclear inclusion bodies, and inflammatory cell infiltration. The tumour tested positive for ChHV5 through conventional PCR targeting the UL30, UL18, UL22, and UL27 genes. Phylogenetic analysis of the DNA Polymerase (UL30) placed the Veracruz variant in the Western Atlantic/Eastern Caribbean cluster along with sequences from Florida, Colombia, Barbados, and Brazil. Additional identification of the CMA1.1 DNA mitochondrial haplotype for this individual supports the connectivity between green turtles from the northern and southern regions of the Gulf of Mexico (GoM) and the Caribbean. It also suggests a potential risk route for ChHV5 infection. This report details the first case of FP linked to ChHV5 in Veracruz and the southwestern GoM. Further research on FP and ChHV5 in these areas is crucial due to their role as habitats for five sea turtle species across various life stages.