Alpha- and gammaherpesviruses in stranded striped dolphins (Stenella coeruleoalba) from Spain: first molecular detection of gammaherpesvirus infection in central nervous system of odontocetes

Abstract

Background Herpesvirus infections in cetaceans have always been attributed to the Alphaherpesvirinae and Gammaherpesvirinae subfamilies. To date, gammaherpesviruses have not been reported in the central nervous system of odontocetes. Case presentation A mass stranding of 14 striped dolphins ( Stenella coeruleoalba ) occurred in Cantabria (Spain) on 18th May 2019. Tissue samples were collected and tested for herpesvirus using nested polymerase chain reaction (PCR), and for cetacean morbillivirus using reverse transcription-PCR. Cetacean morbillivirus was not detected in any of the animals, while gammaherpesvirus was detected in nine male and one female dolphins. Three of these males were coinfected by alphaherpesviruses. Alphaherpesvirus sequences were detected in the cerebrum, spinal cord and tracheobronchial lymph node, while gammaherpesvirus sequences were detected in the cerebrum, cerebellum, spinal cord, pharyngeal tonsils, mesenteric lymph node, tracheobronchial lymph node, lung, skin and penile mucosa. Macroscopic and histopathological post-mortem examinations did not unveil the potential cause of the mass stranding event or any evidence of severe infectious disease in the dolphins. The only observed lesions that may be associated with herpesvirus were three cases of balanitis and one penile papilloma. Conclusions To the authors’ knowledge, this is the first report of gammaherpesvirus infection in the central nervous system of odontocete cetaceans. This raises new questions for future studies about how gammaherpesviruses reach the central nervous system and how infection manifests clinically.

Contribution to Herpesvirus Surveillance in Beaked Whales Stranded in the Canary Islands

“…All the sequences obtained from this study belonged to the Alphaherpesvirinae subfamily in contrast to similar previous studies, in which both alpha and gammaherpesvirus were detected [27,34,35,40,44].…”

“…Herpesvirus sequences detected in BWs from our study should be then analyzed by species. Specifically, sequences from Cuvier's BWs are not novel sequences, displaying higher homologies (100-98.06%) with sequences from striped dolphins stranded in the Mediterranean Sea and central and northeast Atlantic coasts (the Canary Islands and Portugal) (MG437217, KY680657, KY680656, and KJ156331) [26,34,35] (Case 1) and with a sequence detected in other Cuvier's BW from the Mediterranean Sea (KP995682) (Cases 5 and 8). The sequence KP995682 can be considered novel since it shows the highest homology (83.98%) with the sequence detected in the brain of a striped dolphin stranded in the Mediterranean Sea in 2011 (KP995684), which in turn showed the highest homology with the sequence from Case 1 in our study (95.5%) and with the sequence KP995682 (83.98%).…”

“…A percentage positivity of 8.57% (3/35) was found within Cuvier's BW group, while the percentage of positivity rose to 25% (5/20) within the Mesoplodon group. Previously published prevalence of HV infection in stranded cetaceans include: 5.3% in the Western North Pacific (Japan) [40], 3.7% in Brazil [44], 7.8% in Portugal [35], and 41.2% in Cantabria, Spain [34]. Most of the references of HV infection in BWs are case reports: two alphaherpesviruses in a Cuvier's BW and a Blainville's BW stranded in the Canary Islands [17,18] and one gammaherpesvirus in a Blainville's BW stranded in the USA [16].…”

“…Specifically, alphaherpesvirus has been related to fatal systemic infections [25], lymphoid necrosis [17], interstitial nephritis [18] and encephalitis and meningoencephalitis [26][27][28]. Gammaherpesvirus, however, has been described as mainly associated with mucocutaneous, skin, and genital lesions [16,[29][30][31][32][33], although it has been recently described the first detection of gammaherpesvirus in the central nervous system of several striped dolphins (Stenella coeruleoalba) stranded in the Cantabrian Sea, Spain [34].…”

Systematic Determination of Herpesvirus in Free-Ranging Cetaceans Stranded in the Western Mediterranean: Tissue Tropism and Associated Lesions

“…Moreover, these animals are vulnerable to infectious diseases, some of which have implications for human public health and others of which may serve as indicators of environmental distress syndrome [1]. For example, several studies have reported herpesvirus (HV) infection in cetaceans , with prevalences of up to 62.5% [24] or 78.57% [21]. HV can establish latent infections [25,26], and stress and immunosuppression can then cause the virus to revert to an actively replicating state [27].…”