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Since 2010, Guiana dolphin morbillivirus (GDMV; family Paramyxoviridae , genus Morbillivirus , species Morbillivirus ceti , syn. Cetacean morbillivirus ) is recognized as the cause of death of multiple cetacean species along the Brazilian coast, including an unusual mortality event in Rio de Janeiro state. Coronaviruses of the genus Gammacoronavirus (family Coronaviridae ) have been previously detected in cetaceans in the northern hemisphere. After the emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for the COVID-19 pandemic and with the potential to affect several mammal species, there is an increased concern about the risk of infection in aquatic mammals. The goal of this study was to molecularly screen the presence of morbillivirus and coronavirus infections in cetaceans stranded in several regions of the Brazilian coast in order to determine their occurrence rates, pathogenicity, and range of potentially susceptible cetacean species. We molecularly tested tissue samples of 118 cetaceans, belonging to 20 species, found stranded in Brazil, between 2015 and 2022. Overall, 2.5% (3/118) of the analyzed cetaceans were positive for GDMV infection: a Guiana dolphin ( Sotalia guianensis ), an Atlantic spotted dolphin ( Stenella frontalis ), and a humpback whale ( Megaptera novaeangliae ). None of the animals were positive for coronavirus. Our findings indicate that the morbillivirus sequence type identified in Indo-Pacific bottlenose dolphins ( Tursiops aduncus ) of Australia and our GDMV sequences from Brazil belong to the same strain. The systematic monitoring of cetacean morbilliviruses is recommended to properly estimate the occurrence rate, pathogenicity and evolution of these viruses, which may help anticipate novel epizooties and reduce their impact on endangered cetacean populations.

Herpesvirus (HV) is widely distributed among cetacean populations, with the highest prevalence reported in the Mediterranean Sea. In this study, a comprehensive analysis was conducted, including epidemiological, phylogenetic, and pathological aspects, with particular emphasis on neuropathology, to better understand the impact of HV in these animals. Our results show a higher presence of HV in males compared to females, with males exhibiting a greater number of positive tissues. Additionally, adults were more frequently affected by HV infection than juveniles, with no infections detected in calves or neonates. The affected species were striped ( Stenella coeruleoalba ) and bottlenose dolphins ( Tursiops truncatus ). The highest positivity rates were observed in the genital system, cerebrum, and skin tissues. Phylogenetic analysis indicated a higher occurrence of Gammaherpesvirus (GHV) sequences but increased genetic diversity within Alphaherpesvirus (AHV). Key neuropathological features included astro-microgliosis (n = 4) and meningitis with minimal to mild perivascular cuffing (n = 2). The presence of concurrent infections with other pathogens, particularly cetacean morbillivirus (CeMV), underscores the complex nature of infectious diseases in cetaceans. However, the presence of lesions at the Central Nervous System (CNS) with molecular positivity for GHV, excluding the involvement of other potential neurotropic agents, would confirm the potential of this HV subfamily to induce neurological damage. Pathological examination identified lesions in other organs that could potentially be associated with HV, characterized by lymphoid depletion and tissue inflammation. These findings enhance our understanding of HV in odontocetes and highlight the need for ongoing research into the factors driving these infections and their broader implications.

Morbilliviruses, including measles virus (MV), canine distemper virus (CDV), peste des petits ruminants virus, and cetacean morbillivirus pose a significant threat to humans and animals. While the host range of morbilliviruses is generally well-defined, cross-species transmission events with significant mortality have also been reported. Their entry into immune cells, the primary targets of morbilliviruses, relies on the signaling lymphocytic activation molecule (SLAM), also known as SLAMF1 or CD150. In this study, we hypothesize that the ability of morbilliviruses to utilize heterologous SLAM receptors stems from evolutionarily conserved structural determinants within the SLAM protein and that minimal genetic changes in the viral receptor-binding H protein can enable adaptation to novel hosts. To test this, we systematically assessed SLAM utilization and adaptation by diverse morbilliviruses. We found that most morbilliviruses efficiently utilize SLAM from multiple host species, including Myotis bat SLAM, but not human SLAM. Only MV could efficiently utilize human SLAM. Additionally, unlike other morbilliviruses, MV utilized Myotis bat SLAM inefficiently. As an example of morbillivirus adaptation to non-host animal SLAM, we conducted an MV adaptation experiment with Myotis bat SLAM. We demonstrated that MV readily adapted to utilize Myotis bat SLAM by acquiring a single N187Y mutation in its hemagglutinin protein. Notably, hypothetical ancestral SLAMs acted as universal receptors for all morbilliviruses. These results reinforced that morbillivirus receptor usage is primarily supported by evolutionarily conserved structural features of SLAM, highlighting a molecular basis that enables morbilliviruses to rapidly adapt to diverse animal SLAMs.

A northern Gulf of Mexico (GoM) cetacean unusual mortality event (UME) involving primarily bottlenose dolphins (Tursiops truncatus) in Louisiana, Mississippi, and Alabama began in February 2010 and continued into 2014. Overlapping in time and space with this UME was the Deepwater Horizon (DWH) oil spill, which was proposed as a contributing cause of adrenal disease, lung disease, and poor health in live dolphins examined during 2011 in Barataria Bay, Louisiana. To assess potential contributing factors and causes of deaths for stranded UME dolphins from June 2010 through December 2012, lung and adrenal gland tissues were histologically evaluated from 46 fresh dead non-perinatal carcasses that stranded in Louisiana (including 22 from Barataria Bay), Mississippi, and Alabama. UME dolphins were tested for evidence of biotoxicosis, morbillivirus infection, and brucellosis. Results were compared to up to 106 fresh dead stranded dolphins from outside the UME area or prior to the DWH spill. UME dolphins were more likely to have primary bacterial pneumonia (22% compared to 2% in non-UME dolphins, P = .003) and thin adrenal cortices (33% compared to 7% in non-UME dolphins, P = .003). In 70% of UME dolphins with primary bacterial pneumonia, the condition either caused or contributed significantly to death. Brucellosis and morbillivirus infections were detected in 7% and 11% of UME dolphins, respectively, and biotoxin levels were low or below the detection limit, indicating that these were not primary causes of the current UME. The rare, life-threatening, and chronic adrenal gland and lung diseases identified in stranded UME dolphins are consistent with exposure to petroleum compounds as seen in other mammals. Exposure of dolphins to elevated petroleum compounds present in coastal GoM waters during and after the DWH oil spill is proposed as a cause of adrenal and lung disease and as a contributor to increased dolphin deaths.

Feline morbillivirus was first identified in healthy and diseased stray cats captured in Hong Kong. Recently, it was demonstrated that the virus circulates within cat populations in Japan, Italy, Germany, and the USA. Importantly, an association between feline morbillivirus infection and chronic kidney disease was suggested by histological analysis of kidney tissue of infected cats. The aim of this study was to verify the presence and examine the genetic diversity of feline morbilliviruses associated with infections of domestic cats in Brazil. Seventeen cats without clinical manifestations of urinary tract diseases from a multi-cat household and 35 random client-owned cats admitted to the Teaching Veterinary Hospital for a variety of reasons were evaluated for paramyxoviral infection and the presence of uropathy. A fragment of the paramyxoviral L gene was amplified from urine samples using a reverse transcription semi-nested PCR assay. For the first time, we detected a feline morbillivirus strain that was genetically related to viral strains previously characterized in Japan in urine samples from cats in South America, in Brazil. This together with the recent description of feline morbillivirus identification within cat populations in the USA, suggests a possible widespread distribution of this viral agent on the American continent. Our data demonstrated feline morbillivirus RNA shedding mostly in the urine of cats without clinical, laboratorial, or ultrasonographic signs of urinary tract diseases. In contrast to previously published findings that associated feline morbillivirus infection with chronic kidney disease, we did not observe a clear relationship between feline morbillivirus RNA shedding in urine and kidney disease in the cats evaluated.

Following the X-Press Pearl maritime disaster off the coast of Sri Lanka, a stranded spinner dolphin (Stenella longirostris) was recovered, and the cause of death was investigated. Post-mortem examinations revealed evidence of by-catch, but a natural coinfection with dolphin morbillivirus (DMV) and gammaherpesvirus was detected by further analyses, marking the first documented case of a dual viral infection in this species within the region. Molecular diagnostics, including PCR and sequencing, were performed on tissue imprints collected on FTA® cards, confirming the presence of DMV in the prescapular lymph node and gammaherpesvirus in the lesions in the oral cavity. The concurrent detection of DMV and gammaherpesvirus raises significant concerns regarding the potential impacts of environmental stressors, such as chemical pollutants from the X-Press Pearl maritime disaster, on exacerbating susceptibility to viral infections in marine mammals. These findings highlight the need for ongoing surveillance of cetacean populations in the Indian Ocean to better understand pathogen circulation and health and conservation implications of anthropogenic activities on the marine ecosystem.

The monitoring of herpesvirus infection provides useful information when assessing marine mammals’ health. This paper shows the prevalence of herpesvirus infection (80.85%) in 47 cetaceans stranded on the coast of the Valencian Community, Spain. Of the 966 tissues evaluated, 121 tested positive when employing nested-PCR (12.53%). The largest proportion of herpesvirus-positive tissue samples was in the reproductive system, nervous system, and tegument. Herpesvirus was more prevalent in females, juveniles, and calves. More than half the DNA PCR positive tissues contained herpesvirus RNA, indicating the presence of actively replicating virus. This RNA was most frequently found in neonates. Fourteen unique sequences were identified. Most amplified sequences belonged to the Gammaherpesvirinae subfamily, but a greater variation was found in Alphaherpesvirinae sequences. This is the first report of systematic herpesvirus DNA and RNA determination in free-ranging cetaceans. Nine (19.14%) were infected with cetacean morbillivirus and all of them (100%) were coinfected with herpesvirus. Lesions similar to those caused by herpesvirus in other species were observed, mainly in the skin, upper digestive tract, genitalia, and central nervous system. Other lesions were also attributable to concomitant etiologies or were nonspecific. It is necessary to investigate the possible role of herpesvirus infection in those cases.

Feline morbillivirus infections have gained increased attention due to repeated reports of their association with urinary tract disease in cats. In the present study, 112 serum samples from free-roaming domestic cats in Chile were tested for antibodies against feline morbillivirus genotypes 1 and 2 (FeMV-1 and FeMV-2) using an indirect immunofluorescence assay. In total, 63% of the animals showed antibodies against one or both FeMV genotypes. Antibodies directed exclusively against FeMV-2 were significantly more prevalent in male cats. The correlation of sex and FeMV-2 infection might give insight into potential routes of transmission. We provide, for the first time, serological data on FeMV in Chile.

Cetacean morbillivirus (CeMV) is a major threat to cetaceans worldwide, causing individual deaths and outbreaks of mass mortality. Based on partial sequences of the viral phosphoprotein, CeMV is subclassified into seven strains and two distinct lineages. To date, only CeMV-1 strains, including the dolphin morbillivirus (DMV), have been completely sequenced. The CeMV-2 lineage was first reported in Guiana dolphins (Sotalia guianensis) in Brazil and was associated with an unusual mortality event in 2017–2018. Here we provide the nearly complete Guiana dolphin morbillivirus (GDMV) genome sequence, representing the first within the CeMV-2 lineage. GDMV was isolated using Vero.DogSLAMtag cells, the viral RNA was extracted, and deep sequencing analysis was performed. Gaps in the viral genome were completed by Sanger sequencing. The final genome length was 15,607 nucleotides covering 99.3% of the DMV reference genome, including full sequences of the six structural proteins encoded by morbillivirus. The sequence similarity was 74–77.9% to other CeMV strains, with highest identity to the DMV. The complete L protein amino acid sequence comparison-based taxonomy indicates that GDMV is a distinct morbillivirus species; however, as GDMV and CeMV-1 strains infect a similar host spectrum, our findings support that GDMV represents a new CeMV-2 lineage.

Background Feline morbillivirus (FeMV) has been associated with renal pathology in cats; however, the specific pathological alterations caused by FeMV infection remain controversial. This study aimed to investigate histopathological changes, viral localization, and apoptotic activity in the kidneys of FeMV-infected cats. Methods Kidney tissues from 150 deceased cats with suspected or confirmed chronic kidney disease (CKD) were screened for FeMV using conventional reverse-transcription PCR (cRT-PCR). Positive cases were genotyped and quantified for viral load using reverse-transcription digital PCR (RT-dPCR). A control group of nine FeMV-negative kidneys with CKD was included for comparison. Histological evaluation was conducted using hematoxylin and eosin (H&E), periodic acid–Schiff (PAS), and Masson’s trichrome staining. Immunohistochemistry (IHC) and in situ hybridization (ISH) were employed to localize viral antigens and assess expression of apoptotic markers, including cleaved caspase-3 (cCasp3), B-cell lymphoma 2 (BCL-2), and BCL-2–associated X protein (BAX). Results FeMV RNA was detected in 6% (9/150) of kidneys, all classified as genotype 1. Histological findings in FeMV-positive cases included eosinophilic intracytoplasmic inclusion bodies, lymphoplasmacytic tubulointerstitial nephritis (TIN) and varying degrees of fibrosis. FeMV antigens were localized in the renal tubular epithelial cells. Statistically, cCasp3 expression ( P  = 0.005) and interstitial fibrosis ( P  = 0.040) were significantly higher in FeMV-positive cases than in FeMV-negative controls. No significant differences were observed for TIN, BAX, or BCL-2 expression ( P  > 0.05). Among FeMV-positive cases, viral load was significantly associated with cCasp3 expression ( P  = 0.049), but not with TIN, fibrosis, BAX, or BCL-2 expression. Spearman’s correlation revealed a strong positive correlation between viral load and cCasp3 expression (ρ = 0.8222, P  = 0.007). Conclusions FeMV infection in cats was associated with increased caspase-3–mediated apoptotic activity and interstitial fibrosis in kidney tissue, particularly in cases with higher viral loads. While these findings suggest a possible role for FeMV in renal injury, the absence of consistent associations with other apoptotic markers and inflammatory parameters indicates that additional factors may contribute to disease progression. Further studies, including longitudinal and experimental investigations, are needed to clarify the pathogenic mechanisms and the clinical relevance of FeMV in feline kidney disease.