Carriage of antibiotic resistant bacteria in endangered and declining Australian pinniped pups

The rapid emergence of antimicrobial resistance (AMR) is a major concern for wildlife and ecosystem health globally. Genetic determinants of AMR have become indicators of anthropogenic pollution due to their greater association with humans and rarer presence in environments less affected by humans. The objective of this study was to determine the distribution and frequency of the class 1 integron, a genetic determinant of AMR, in both the faecal microbiome and in Escherichia coli isolated from neonates of three pinniped species. Australian sea lion ( Neophoca cinerea ), Australian fur seal ( Arctocephalus pusillus doriferus ) and long-nosed fur seal ( Arctocephalus forsteri ) pups from eight breeding colonies along the Southern Australian coast were sampled between 2016-2019. DNA from faecal samples ( n =309) and from E. coli ( n =795) isolated from 884 faecal samples were analysed for class 1 integrons using PCRs targeting the conserved integrase gene ( intI ) and the gene cassette array. Class 1 integrons were detected in A. p. doriferus and N. cinerea pups sampled at seven of the eight breeding colonies investigated in 4.85% of faecal samples ( n =15) and 4.52% of E. coli isolates ( n =36). Integrons were not detected in any A. forsteri samples. DNA sequencing of the class 1 integron gene cassette array identified diverse genes conferring resistance to four antibiotic classes. The relationship between class 1 integron carriage and the concentration of five trace elements and heavy metals was also investigated, finding no significant association. The results of this study add to the growing evidence of the extent to which antimicrobial resistant bacteria are polluting the marine environment. As AMR determinants are frequently associated with bacterial pathogens, their occurrence suggests that these pinniped species are vulnerable to potential health risks. The implications for individual and population health as a consequence of AMR carriage is a critical component of ongoing health investigations.

Molecular identification of the first Galapagos fur seal (Arctocephalus galapagoensis) reported on the central coast of Oaxaca

Several sightings of different pinniped species have been recorded outside their typical areas of distribution. In May 2019, pinniped yearlings were sighted on 4 occasions on the central coast of Oaxaca, Mexico. One of them was found injured in La Escobilla (Oaxaca, Mexico) and was transported immediately to the Centro Mexicano de la Tortuga for rehabilitation. Visual identification of the species was inconclusive, as young individuals of several fur seal species can be very similar. A molecular analysis was thus performed to confirm the species. DNA was extracted from the individual, and a fragment of the mitochondrial DNA control region was sequenced and aligned with several sequences of other fur seal species. A parsimony analysis was performed, and the tree revealed that the individual was a Galapagos fur seal, Arctocephalus galapagoensis. This is the first record of this species on the central coast of Oaxaca. The atypical presence of this species in the country could be related to high sea surface temperatures associated with events such as El Niño.

A Comparison of Parapoxviruses in North American Pinnipeds

Parapoxviruses cause nodular lesions on the skin and mucosal membranes of pinnipeds and infections by these viruses have been documented worldwide. Seal parapoxvirus is currently classified as a tentative species of the Parapoxvirus genus. Tissue or swab samples were analyzed from 11 pinnipeds of different host species undergoing rehabilitation on the east and west coasts of the United States of America (USA) that were positive for parapoxvirus. The aim of the study was to compare parapoxvirus sequences of fragments of the B2L, DNA polymerase, GIF and viral interleukin-10 ortholog (vIL-10) genes and to examine the evolutionary relationship between viruses detected in different pinniped species and at different locations with other members of the Parapoxvirus genus, such as Orf virus (ORFV), Bovine papular stomatitis virus (BPSV) and Pseudocowpox virus (PCPV). The sequence analysis showed that the parapoxvirus sequences from the pinnipeds differed significantly from those found in terrestrial hosts and that they formed a separate cluster within the genus. Our results suggest that transmission of the same parapoxvirus strain is possible between different species, including between members of different families (phocids and otariids). Animals belonging to the same species but living in distant geographic locations presented genetically distant parapoxviruses. The findings of this study demonstrate that sealpox lesions in pinnipeds of different species are caused by viruses that belong to the Parapoxvirus genus but have significant genetic differences compared to the established virus species in terrestrial hosts, thus strongly supporting the classification of pinniped parapoxvirus as a new species of the genus.

Amyloid β and tau pathology in brains of aged pinniped species (sea lion, seal, and walrus)

Alzheimer’s disease (AD) is characterized by the accumulation of amyloid-β (Aβ) as senile plaques and cerebral amyloid angiopathy, and hyperphosphorylated tau (hp-tau) as neurofibrillary tangles in the brain. The AD-related pathology has been reported in several non-human animals, and most animals develop only the Aβ or tau pathology. We herein describe the Aβ and hp-tau pathology in the brains of aged pinniped species (seal, sea lion, and walrus). Molecular analyses revealed that the sequence of pinniped Aβ was identical to that of human Aβ. Histopathological examinations detected argyrophilic plaques composed of Aβ associated with dystrophic neurites in the cerebral cortex of aged pinnipeds. Astrogliosis and microglial infiltration were identified around Aβ plaques. Aβ deposits were observed in the blood vessel walls of the meninges and cerebrum. Pinniped tau protein was physiologically subjected to alternative splicing at exons 2, 3, and 10, and presented as five isoforms: two 3-repeat tau isoforms (1N3R, 2N3R) and three 4-repeat tau isoforms (0N4R, 1N4R, 2N4R); 0N3R tau isoform was absent. Histopathological examinations revealed argyrophilic fibrillar aggregates composed of hp-tau in the neuronal somata and neurites of aged pinniped brains. Few hp-tau aggregates were found in oligodendrocytes and microglia. Biochemically, hp-tau of the 3-repeat and 4-repeat isoforms was detected in brain sarkosyl-insoluble fractions. Aβ and hp-tau both predominantly accumulated in the neocortex, particularly the frontal cortex. Furthermore, the activation of GSK-3β was detected within cells containing hp-tau aggregates, and activated GSK-3β was strongly expressed in cases with severe hp-tau pathologies. The present results suggest that, in association with Aβ deposition, the activation of GSK-3β contributes to hp-tau accumulation in pinniped brains. Here, we report that pinniped species naturally accumulate Aβ and tau with aging, similar to the human AD pathology.

Harbour Seals: Population Structure, Status, and Threats in a Rapidly Changing Environment

The harbour seal (Phoca vitulina) is the world’s most widely distributed pinniped species ranging from temperate to Arctic regions (30–78.5° N in the Atlantic, 28–61.2° N in the Pacific), but no detailed overview of the species status exists. The aims of this review are to (i) provide current information on the genetic structure, population status, and threats; (ii) review potential consequences of a changing climate; and (iii) identify knowledge gaps to guide future research and monitoring. Although the species is globally abundant, wide differences exist across the species’ broad range. As climate warms, populations at the edges of the species’ distributional range are likely to be more affected. The primary climate-related drivers include: (i) changes in weather patterns, which can affect thermoregulation; (ii) decrease in availability of haul-out substrates; (iii) large-scale changes in prey availability and inter-specific competition; (iv) shifts in the range of pathogens; (v) increase in temperature favouring the biotransformation of contaminants; and (vi) increased exposure to pollutant from increased freshwater run-off. Multiple anthropogenic stressors may collectively impact some populations. Coordinated monitoring efforts across and within regions is needed. This would allow for a spatially explicit management approach including population-specific responses to known stressors.

First record of tuberculosis lesions in zooarchaeological samples of otariid pinnipeds. New aspects of the pre-european origin of human tuberculosis in South America and dissemination mechanisms of Mycobacterium pinnipedii in the Southern Hemisphere

In 2003 Mycobacterium pinnipedii was described as responsible for producing tuberculosis (TB) in living otariid pinnipeds from Argentina and Australia. It is the only member of marine origin within the Mycobacterium tuberculosis Complex (MTBC), which also affects other domestic and wild mammals, and humans. Based on several pre-Columbian records of human tuberculosis in South America, in 2010-2011 a new hypothesis about the origin of this zoonosis through otariid pinnipeds arose. In 2014, this hypothesis was confirmed based on the study of ancient DNA from three mummies (700-1,000 years BP) of the Chiribaya culture (Peru). Since there were no records of TB bone lesions in zooarchaeological samples of otariid pinnipeds from South America and the rest of the world, our study aimed at examining zooarchaeological samples of pinnipeds from coastal sites of the Beagle Channel (Tierra del Fuego, Argentina), being the oldest Túnel I (6,400-4,300 years BP). A total of 4,138 vertebrae were analyzed, of which 0.46 % showed lesions compatible with TB. In addition, we propose a new hypothesis on possible mechanisms of Mycobacterium pinnipedii dissemination that would explain the transmission routes to the different otariid pinniped species of the Southern Hemisphere. Mycobacterium pinnipedii is one of the most aggressive mycobacteria of the MTBC and of high risk for humans.

New host and geographical records for Parafilaroides normani (Nematoda: Filaroididae) Dailey, 2009 in South American fur seal, Arctocephalus australis, from southern Brazil

Lungworms are a common finding in seals and fur seals around the world. However, from existing records, the biogeographical distribution of filaroid helminths appears to be restricted, and these parasites are endemic in only certain areas and species, mainly in the Northern Hemisphere. The occurrence of infection in pinniped species in the Southern Hemisphere is scarce. The objective of this work is to verify the prevalence of lungworms in Arctocephalus australis in waters off the southern coast of Brazil. Twenty subadult specimens of A. australis found recently dead on the southern coast of Brazil were necropsied and their lungs were examined. Parasitic cysts were found in only one specimen (prevalence of 5%). The helminths were morphologically identified as Parafilaroides normani (Metastrongyloidea: Filaroididae). This helminth species has been reported in pinnipeds from Australia, New Zealand and South Africa. This is the first record of P. normani in A. australis and for the western South Atlantic, providing additional data regarding the biogeographic distribution of the parasite.