New potential insight for cetacean welfare assessments: molecular detection of cetacean poxvirus through a non-invasive skin sampling device

Abstract

Animal welfare can be understood as animals’ adaptation to their environment, resulting in a balance of positive and negative stimuli affecting physical and physiological health as well as emotional state and behaviour. Thus, health is an important aspect of welfare, being especially relevant in welfare assessments. In last decades, characteristic poxvirus-like lesions have been reported as a potential general health indicator in both freeranging and under human care odontocetes (CePV-1) and mysticetes (CePV-2). There is an overall agreement that these distinguishable lesions are caused due to chronic environmental disturbances leading into immunosuppression and, therefore, more susceptibility to disease. Most studies have related the presence of these lesions with tattoo-skin-disease through visual assessments, depriving of diagnostic methods to correctly corroborate CePV infection. On the other hand, some authors have used biopsy as a skin sampling procedure to further either histologically or molecularly determine viral infection. Nevertheless, extrapolate this sampling technique on cetaceans under human care might be invasive, adding to this that it implies long-term handling which can negatively affect animals’ wellbeing. Accordingly, aiming to address skin biopsies intrusiveness, we developed a model study validating cytology cell samplers (CCS) as a non-invasive skin sampling device to detect CePV-1 in twelve tattoo-like-lesions from two stranded cetaceans on Canary coasts. To sustain the results, two different genomic extraction protocols to compare both skin sampling procedures were performed, using DNA Tissue Kit STM (QuickGene, Kurabo, Japan) and DNeasyTM Blood and Tissue Kit (Qiagen, Inc., Valencia, CA). Our findings show that, through the first extraction kit, a percentage of positivity of 83.3% with CCS was obtained compared to 91.7% with biopsies. However, better results were obtained with second extraction kit with 100% of positivity using CCS. Confirming poxvirus lesions in cetaceans under human care through CCS could be a potential health measure to welfare evaluation.