FIBROPAPILLOMATOSIS AND CHHV5 CIRCULATION IN JUVENILE GREEN TURTLES FROM COASTAL DEVELOPMENTAL HABITATS IN BRAZIL

ChHV5 circulation in juvenile Chelonia mydas

Abstract

Fibropapillomatosis (FP) is a tumor-associated disease affecting marine turtles worldwide and has been linked to ChHV5 infection, although disease expression depends on interactions among viral, host, and environmental factors. This study investigated the occurrence of ChHV5 in blood and tumor samples from juvenile Chelonia mydas sampled across five coastal developmental habitats distributed along the Brazilian coast. A total of 157 individuals were examined. Fibropapillomatosis was recorded in 27.4% of turtles, with significant variation among sampling localities (Fisher’s exact test, p < 0.001), and the highest prevalence was observed in Espírito Santo. ChHV5 DNA was detected in 8.3% of blood samples using the UL18 genetic target, including both individuals with and without visible FP, and blood-based viral detection was significantly associated with clinical FP status. Tumor samples collected opportunistically from seven turtles with clinically evident FP captured in Niterói, Rio de Janeiro, were all positive for ChHV5, reinforcing the association between ChHV5 and fibropapillomatous lesions. Viral detection occurred across multiple sampled localities, with no significant association between viral detection and sampling location. The UL18 assay showed a lower analytical detection limit than the UL30 assay under the conditions evaluated. Detection in turtles without visible FP supports viral occurrence beyond clinically apparent disease but does not establish infectiousness or transmission. Blood PCR can complement clinical surveillance, although negative blood results do not exclude infection. Conservation applications require integrated interpretation of clinical findings, molecular results, sampling effort, and habitat information.