Survey of selected viral agents (herpesvirus, adenovirus and hepatitis E virus) in liver and lung samples of cetaceans, Brazil

Hepatic and pulmonary lesions are common in cetaceans, despite their poorly understood viral etiology. Herpesviruses (HV), adenoviruses (AdV) and hepatitis E virus (HEV) are emerging agents in cetaceans, associated with liver and/or pulmonary damage in mammals. We isolated and molecularly tested DNA for HV and AdV (n = 218 individuals; 187 liver and 108 lung samples) and RNA for HEV (n = 147 animals; 147 liver samples) from six cetacean families. All animals stranded or were bycaught in Brazil between 2001 and 2021. Positive-animals were analyzed by histopathology. Statistical analyses assessed if the prevalence of viral infection could be associated with the variables: species, family, habitat, region, sex, and age group. All samples were negative for AdV and HEV. Overall, 8.7% (19/218) of the cetaceans were HV-positive (4.8% [9/187] liver and 11.1% [12/108] lung), without HV-associated lesions. HV-prevalence was statistically significant higher in Pontoporiidae (19.2%, 10/52) when compared to Delphinidae (4.1%, 5/121), and in southeastern (17.1%, 13/76)-the most industrialized Brazilian region-when compared to the northeastern region (2.4%, 3/126). This study broadens the herpesvirus host range in cetaceans, including its description in pygmy sperm whales (Kogia breviceps) and humpback whales (Megaptera novaeangliae). Further studies must elucidate herpesvirus drivers in cetaceans.

Cerebral and cardiac congenital malformations in neonatal West Indian manatees (Trichechus manatus)

Strandings of live new-born West Indian manatees (WIMs; Trichechus manatus) are one of the main challenges for the conservation of this species in Brazil, particularly in the northeastern states. Congenital malformations (CMs) are rare in sirenians. We identified CMs in two of 19 stranded WIMs that were rescued, rehabilitated and subjected to complete pathological examinations in Ceará and Rio Grande do Norte States between 1992 and 2017. In case 1, dilation of the cerebral lateral and fourth ventricles with abundant cerebrospinal fluid (internal hydrocephalus), was diagnosed. Furthermore, this animal developed necrotizing enterocolitis associated with pneumatosis intestinalis and aspiration pneumonia late during rehabilitation. Cardiac malformations in case 2 included: right ventricle hypoplasia with marked stenosis of the tricuspid outflow, high ventricular septal defect, segmental pulmonary artery aneurysm, mitral valve haemocyst and left ventricular hypertrophy. Herein, we provide the first description of a neural tube defect, specifically a developmental internal hydrocephalus, and multiple cardiac congenital anomalies, together with their respective clinicopathological features in manatees. Although the aetiology of the CMs remains unknown in these cases, a genetic basis is plausible given the low genetic variability in this population. These cases add to the body of knowledge on health and disease aspects of manatees and may provide scientific basis for future medical and conservation efforts on neonatal WIMs.

Genetic characterization, molecular epidemiology, and phylogenetic relationships of insect-specific viruses in the taxon Negevirus

The recently described taxon Negevirus is comprised of a diverse group of insect-specific viruses isolated from mosquitoes and phlebotomine sandflies. In this study, a comprehensive genetic characterization, molecular, epidemiological and evolutionary analyses were conducted on nearly full-length sequences of 91 new negevirus isolates obtained in Brazil, Colombia, Peru, Panama, USA and Nepal. We demonstrated that these arthropod restricted viruses are clustered in two major phylogenetic groups with origins related to three plant virus genera (Cilevirus, Higrevirus and Blunevirus). Molecular analyses demonstrated that specific host correlations are not present with most negeviruses; instead, high genetic variability, wide host-range, and cross-species transmission were noted. The data presented here also revealed the existence of five novel insect-specific viruses falling into two arthropod-restrictive virus taxa, previously proposed as distinct genera, designated Nelorpivirus and Sandewavirus. Our results provide a better understanding of the molecular epidemiology, evolution, taxonomy and stability of this group of insect-restricted viruses.

Renal lesions in cetaceans from Brazil

This study reports the occurrence of renal lesions in cetaceans from the coast of Brazil subjected to necropsy examination between 1996 and 2011. The animals (n = 192) were by-caught in fishing nets, were found dead on beaches or died despite attempted rehabilitation. Kidney samples were evaluated grossly and microscopically and, depending on the histopathological findings, immunohistochemical and ultrastructural analyses were conducted. Due to autolysis, a diagnosis was reached in only 128 animals, of which 82 (64.1%) had kidney lesions. Cystic renal disease was the most common lesion observed in 34 cases (26.6%) and these were classified as simple cysts in eight cases (6.3%), polycystic kidney disease in one rough-toothed dolphin (Steno bredanensis), secondary glomerulocystic disease in 16 cases (12.5%) and primary glomerulocystic disease in nine cases (7%). Other lesions included membranous glomerulonephritis (28 cases; 21.9%), membranoproliferative glomerulonephritis (20 cases; 15.6%), lymphoplasmacytic interstitial nephritis (21 cases; 16.4%), lipidosis (19 cases; 14.8%), glomerulosclerosis (8 cases; 6.3%) and pyogranulomatous nephritis(five cases; 3.9%); two of the later were associated with the migration of nematode larvae. Additionally, tubular adenoma was identified in a Franciscana (Pontoporia blainvillei). The pathological implications of these lesions are discussed according the cause of death, age or sex of the animals. Furthermore, the lesions were compared with those of other marine and terrestrial mammals, including man.

Yellow fever virus in Haemagogus leucocelaenus and Aedes serratus mosquitoes, southern Brazil, 2008

Yellow fever virus (YFV) was isolated from Haemagogus leucocelaenus mosquitoes during an epizootic in 2001 in the Rio Grande do Sul State in southern Brazil. In October 2008, a yellow fever outbreak was reported there, with nonhuman primate deaths and human cases. This latter outbreak led to intensification of surveillance measures for early detection of YFV and support for vaccination programs. We report entomologic surveillance in 2 municipalities that recorded nonhuman primate deaths. Mosquitoes were collected at ground level, identified, and processed for virus isolation and molecular analyses. Eight YFV strains were isolated (7 from pools of Hg. leucocelaenus mosquitoes and another from Aedes serratus mosquitoes); 6 were sequenced, and they grouped in the YFV South American genotype I. The results confirmed the role of Hg. leucocelaenus mosquitoes as the main YFV vector in southern Brazil and suggest that Ae. serratus mosquitoes may have a potential role as a secondary vector.