Herpesvirus and adenovirus surveillance in threatened wild West Indian (Trichechus manatus) and Amazonian manatees (Trichechus inunguis), Brazil

Abstract

The family Trichechidae (order Sirenia) comprises three species: African (Trichechus senegalenses), West Indian (T. manatus), WIM)], and the Amazonian manatees (T. inunguis, AMM). Whereas WIM inhabits both riverine and coastal systems in the western Atlantic, AMM is the only exclusively freshwater sirenian, endemic to the Amazon River Basin. The study of infectious agents is essential to species conservation, especially considering that both species are classified as Vulnerable by the IUCN Red List and as Endangered by the Brazilian Red List. The current knowledge about viral agents in sirenians is scarce. Herpesviruses and adenovirus are DNA viruses able to infect and cause disease in a wide range of hosts. Herein, we used panPCR protocols to survey herpesvirus and adenovirus in blood samples of wild WIM (n = 23) and AMM (n = 26) under human care in Brazil. Herpesvirus DNA was detected in one juvenile female WIM (1/23; 4.3%; 95% CI -4.7 – 13.3) from Ceará state and in four AMM (two juvenile females, a juvenile male, and an adult female; 4/26; 15.4%; 95% CI 0.5 – 30.3) from Amazonas state. The two different gammaherpesvirus DNA polymerase sequence types identified (one per species, a sequence type in a WIM and another one in three AMM) were highly similar (99% nucleotide identity) to Trichechid herpesvirus 1, reported in West Indian manatees of Florida (USA), and 100% identical when translated into amino acids. A herpesviral glycoprotein B sequence was identified in two AMM. None of the samples was positive to adenovirus. To the authors’ knowledge, this is the first herpesvirus detection in manatees from South America, expanding the herpesvirus geographical range, and the first in WIM and AMM worldwide. Our findings suggest (i) that West Indian and Amazonian manatees are possibly the natural hosts of the detected herpesvirus, and (ii) coevolution of that gammaherpesvirus with Trichechus. Future studies are necessary to characterize the obtained virus and elucidate potential pathological effects (if any) in these species.