Identification of a novel Neorickettsia species in a Kemp's ridley sea turtle with granulomatous nephritis and development of a quantitative PCR assay.

An adult male Kemp's ridley turtle was found dead on the coast of Kenedy County, Texas, in August 2019 with bilateral severe, diffuse granulomatous nephritis. Pan-bacterial 16S rRNA gene polymerase chain reaction (PCR) and amplicon sequencing of affected tissue indicated the presence of a Neorickettsia. Neorickettsia is a genus of obligate intracellular Alphaproteobacteria that are transmitted by digenean trematodes. For further characterization, primers were designed to amplify and sequence the groEL gene. Phylogenetic analysis found that the organism was distinct from other known species to a degree consistent with a novel species. Immunohistochemistry using an antibody directed against a Neorickettsia surface protein showed bacterial clusters within the renal granulomas. A species-specific quantitative PCR was designed and detected the organism within the liver and colon of the index case. A quantitative PCR survey of grossly normal kidneys opportunistically collected from additional stranded sea turtle kidneys detected this organism in five of 15 Kemp's ridley turtles, two of nine green turtles, and neither of two loggerhead turtles. Recognition of this novel organism in an endangered species is concerning; additional work is underway to further characterize the potential of this organism as a pathogen of sea turtles.

Fibropapillomatosis and Chelonid Alphaherpesvirus 5 Infection in Kemp's Ridley Sea Turtles (Lepidochelys kempii).

Fibropapillomatosis (FP), a debilitating, infectious neoplastic disease, is rarely reported in endangered Kemp's ridley sea turtles (Lepidochelys kempii). With this study, we describe FP and the associated chelonid alphaherpesvirus 5 (ChHV5) in Kemp's ridley turtles encountered in the United States during 2006-2020. Analysis of 22 case reports of Kemp's ridley turtles with FP revealed that while the disease was mild in most cases, 54.5% were adult turtles, a reproductively valuable age class whose survival is a priority for population recovery. Of 51 blood samples from tumor-free turtles and 12 tumor samples from turtles with FP, 7.8% and 91.7%, respectively, tested positive for ChHV5 DNA via quantitative polymerase chain reaction (qPCR). Viral genome shotgun sequencing and phylogenetic analysis of six tumor samples show that ChHV5 sequences in Kemp's ridley turtles encountered in the Gulf of Mexico and northwestern Atlantic cluster with ChHV5 sequences identified in green (Chelonia mydas) and loggerhead (Caretta caretta) sea turtles from Hawaii, the southwestern Atlantic Ocean, and the Caribbean. Results suggest an interspecific, spatiotemporal spread of FP among Kemp's ridley turtles in regions where the disease is enzootic. Although FP is currently uncommon in this species, it remains a health concern due to its uncertain pathogenesis and potential relationship with habitat degradation.

Evolutionary Comparisons of Chelonid Alphaherpesvirus 5 (ChHV5) Genomes from Fibropapillomatosis-Afflicted Green (Chelonia mydas), Olive Ridley (Lepidochelys olivacea) and Kemp's Ridley (Lepidochelys kempii) Sea Turtles.

The spreading global sea turtle fibropapillomatosis (FP) epizootic is threatening some of Earth's ancient reptiles, adding to the plethora of threats faced by these keystone species. Understanding this neoplastic disease and its likely aetiological pathogen, chelonid alphaherpesvirus 5 (ChHV5), is crucial to understand how the disease impacts sea turtle populations and species and the future trajectory of disease incidence. We generated 20 ChHV5 genomes, from three sea turtle species, to better understand the viral variant diversity and gene evolution of this oncogenic virus. We revealed previously underappreciated genetic diversity within this virus (with an average of 2035 single nucleotide polymorphisms (SNPs), 1.54% of the ChHV5 genome) and identified genes under the strongest evolutionary pressure. Furthermore, we investigated the phylogeny of ChHV5 at both genome and gene level, confirming the propensity of the virus to be interspecific, with related variants able to infect multiple sea turtle species. Finally, we revealed unexpected intra-host diversity, with up to 0.15% of the viral genome varying between ChHV5 genomes isolated from different tumours concurrently arising within the same individual. These findings offer important insights into ChHV5 biology and provide genomic resources for this oncogenic virus.

Fibropapillomatosis prevalence and distribution in green turtles Chelonia mydas in Texas (USA).

Fibropapillomatosis (FP) is a neoplastic disease that can result in debilitating tumors in sea turtles. Initially identified in Florida, USA in 1937, it has since been detected in green turtle Chelonia mydas populations globally. FP was first identified and confirmed in Texas, USA in 2010. No FP tumors were documented in Texas prior to that year, though many green turtles were encountered and examined using standardized procedures since 1980. The present study was undertaken to identify temporal and spatial trends of FP prevalence in Texas since 2010. From 2010 through 2018, 1919 stranded or incidentally captured green turtles were documented with FP in Texas. FP prevalence was significantly correlated with year, hypothermic stunning, geographic region, and turtle size, as determined by logistic regression. FP was documented in <4.0% of the green turtles examined in Texas from 2010 to 2015, increasing to 21.6% in 2016, 27.3% in 2017, and 35.2% in 2018. More than twice as many hypothermic stunned green sea turtles had FP tumors as compared to those that were not hypothermic stunned. In Texas, FP was most prevalent in south Texas, particularly in the Laguna Madre, and associated channels. FP was more prevalent in turtles with straight carapace lengths 40.0-69.9 cm. The impact of this disease on green turtle population recovery in Texas is not yet apparent.