Mycoplasmas in Australian fur seals (Arctocephalus pusillus doriferus): identification and association with abortion

Molecular Detection and Characterization of Mycoplasma spp. in Marine Mammals, Brazil

Mycoplasma spp. are wall-less bacteria able to infect mammals and are classified as hemotropic (hemoplasma) and nonhemotropic. In aquatic mammals, hemoplasma have been reported in California sea lions (Zalophus californianus) and river dolphins (Inia spp.). We investigated Mycoplasma spp. in blood samples of West Indian manatees (Trichechus manatus), pinnipeds (5 species), and marine cetaceans (18 species) that stranded or were undergoing rehabilitation in Brazil during 2002-2022. We detected Mycoplasma in blood of 18/130 (14.8%) cetaceans and 3/18 (16.6%) pinnipeds. All tested manatees were PCR-negative for Mycoplasma. Our findings indicate that >2 different hemoplasma species are circulating in cetaceans. The sequences from pinnipeds were similar to previously described sequences. We also detected a nonhemotropic Mycoplasma in 2 Franciscana dolphins (Pontoporia blainvillei) that might be associated with microscopic lesions. Because certain hemoplasmas can cause disease and death in immunosuppressed mammals, the bacteria could have conservation implications for already endangered aquatic mammals.

Environmental influences on breeding biology and pup production in Australian fur seals

Knowledge of factors affecting a species' breeding biology is crucial to understanding how environmental variability impacts population trajectories and enables predictions on how species may respond to global change. The Australian fur seal (Arctocephalus pusillus doriferus, AUFS) represents the largest marine predator biomass in southeastern Australia, an oceanic region experiencing rapid warming that will impact the abundance and distribution of prey. The present study (1997-2020) investigated breeding phenology and pup production in AUFS on Kanowna Island, northern Bass Strait. The pupping period varied by 11 days and the median pupping date by 8 days and were negatively correlated to 1- and 2-year lagged winter zonal winds, respectively, within Bass Strait. While there was no temporal trend over the study period, annual pup production (1386-2574 pups) was negatively correlated to 1-year lagged summer zonal winds in the Bonney Upwelling region and positively correlated to the current-year Southern Oscillation Index (SOI). In addition, a fecundity index (ratio of new-born pups to adult females at the median pupping date) was positively correlated with current-year Southern Annular Mode (SAM) conditions. Periods of positive SOI and positive SAM conditions are forecast to increase in coming decades, suggesting advantageous conditions for the Kanowna Island AUFS population.

Sustained reduction in numbers of Australian fur seal pups: Implications for future population monitoring

Fur seal populations in the Southern Hemisphere were plundered in the late 1700s and early 1800s to provide fur for a clothing industry. Millions of seals were killed resulting in potentially major ecosystem changes across the Southern Hemisphere, the consequences of which are unknown today. Following more than a century of population suppression, partly through on-going harvesting, many of the fur seal populations started to recover in the late 1900s. Australian fur seals (Arctocephalus pusillus doriferus), one of the most geographically constrained fur seal species, followed this trend. From the 1940s to 1986, pup production remained at approximately 10,000 per year, then significant growth commenced. By 2007, live pup abundance had recovered to approximately 21,400 per year and recovery was expected to continue However, a species-wide survey in 2013 recorded a 20% decline, to approximately 16,500 live pups. It was not known if this decline was due to 2013 being a poor breeding year or a true population reduction. Here we report the results of a population-wide survey conducted in 2017 and annual monitoring at the most productive colony, Seal Rocks, Victoria that recorded a large decline in live pup abundance (-28%). Sustained lower pup numbers at Seal Rocks from annual counts between 2012–2017 (mean = 2908 ± 372 SD), as well as the population-wide estimate of 16,903 live pups in 2017, suggest that the pup numbers for the total population have remained at the lower level observed in 2013 and that the 5-yearly census results are not anomalies or representative of poor breeding seasons. Potential reasons for the decline, which did not occur range-wide but predominantly in the most populated and long-standing breeding sites, are discussed. To enhance adaptive management of this species, methods for future monitoring of the population are also presented. Australian fur seals occupy several distinct regions influenced by different currents and upwellings: range-wide pup abundance monitoring enables comparisons of ecosystem status across these regions. Forces driving change in Australian fur seal pup numbers are likely to play across other marine ecosystems, particularly in the Southern Hemisphere where most fur seals live.

Mycoplasma miroungirhinis sp. nov. and Mycoplasma miroungigenitalium sp. nov., isolated from northern elephant seals (Mirounga angustirostris), Mycoplasma phocoenae sp. nov., isolated from harbour porpoise (Phocoena phocoena), and Mycoplasma phocoeninasale sp. nov., isolated from harbour porpoise and California sea lions (Zalophus californianus)

Seven novel independent strains of Mycoplasma species were isolated from northern elephant seals (ES2806-NAST, ES2806-GENT, ES3157-GEN-MYC and ES3225-GEN-MYC), a harbour porpoise (C264-GENT and C264-NAST), and a California sea lion (CSL7498). These strains were phenotypically and genetically characterized and compared to the known Mycoplasma species. Four strains (C264-GENT, C264-NAST, CSL7498 and ES2806-NAST) hydrolysed arginine but not urea and did not produce acid from carbohydrates. Strains ES2806-GENT, ES3157-GEN-MYC and ES3225-GEN-MYC did not produced acid from carbohydrates and did not hydrolyse arginine or urea; hence, it is assumed that organic acids are used as the energy source for them. All were isolated and propagated in ambient air supplemented with 5±1 % CO2 at +35–37 °C using either SP4 or PPLO medium. Colonies on solid medium showed a typical fried-egg appearance and transmission electron microscopy revealed a typical mycoplasma cellular morphology. The complete genomes were sequenced for all type strains. Average nucleotide and amino acid identity analyses showed that these novel strains were distant from the phylogenetically closely related Mycoplasma species. Based on these data, we propose four novel species of the genus Mycoplasma , for which the name Mycoplasma miroungirhinis sp. nov. is proposed with the type strain ES2806-NAST (=NCTC 14430T=DSM 110945T), Mycoplasma miroungigenitalium sp. nov. is proposed with the type strain ES2806-GENT (=NCTC 14429T=DSM 110944T) and representative strains ES3157-GEN-MYC and ES3225-GEN-MYC, Mycoplasma phocoenae sp. nov. is proposed with the type strain C264-GENT (=NCTC 14344T=DSM 110687T) and Mycoplasma phocoeninasale sp. nov. is proposed with the type strain C264-NAST (=NCTC 14343T=DSM 110688T) and representative strain CSL7498. The genome G+C contents are 24.06, 30.09, 28.49 and 29.05% and the complete genome sizes are 779 550, 815 486, 693 115, and 776 009 bp for strains ES2806-NAST, ES2806-GENT, C264-GENT and C264-NAST, respectively.

Occurrence of Mycoplasmas in Galapagos Sea Lions (Zalophus wollebaeki) and their Association with Other Respiratory Pathogens

During the 2018 breeding season, an outbreak of respiratory disease occurred among Galapagos sea lions (Zalophus wollebaeki) that inhabit rookeries near urban areas with introduced fauna such as dogs and cats. Several sea lions had nasal discharge and respiratory distress and were in poor body condition. Eighteen sea lions were captured for a general health assessment including collection of blood for serology and nasal discharge for culture and PCR. Samples were analyzed for 15 respiratory pathogens known to infect cats, dogs, and marine mammals. There was no evidence for interspecies pathogen transmission between Galapagos sea lions and domestic animals. Several bacterial pathogens associated with respiratory tract infection in the California sea lion (Zalophus californianus) were isolated. Mycoplasma spp. were identified by PCR in nasal discharge samples but were not the species commonly found in cats and dogs.

The seal louse (Echinophthirius horridus) in the Dutch Wadden Sea: investigation of vector-borne pathogens

BACKGROUND

Belonging to the anopluran family Echinophthiriidae, Echinophthirius horridus, the seal louse, has been reported to parasitise a broad range of representatives of phocid seals. So far, only a few studies have focused on the vector function of echinophthiriid lice, and knowledge about their role in pathogen transmission is still scarce. The current study aims to investigate the possible vector role of E. horridus parasitising seals in the Dutch Wadden Sea.

METHODS

E. horridus seal lice were collected from 54 harbour seals (Phoca vitulina) and one grey seal (Halichoerus grypus) during their rehabilitation period at the Sealcentre Pieterburen, The Netherlands. DNA was extracted from pooled seal lice of individual seals for molecular detection of the seal heartworm Acanthocheilonema spirocauda, the rickettsial intracellular bacterium Anaplasma phagocytophilum, and the cell wall-less bacteria Mycoplasma spp. using PCR assays.

RESULTS

Seal lice from 35% of the harbour seals (19/54) and from the grey seal proved positive for A. spirocauda. The seal heartworm was molecularly characterised and phylogenetically analysed (rDNA, cox1). A nested PCR was developed for the cox1 gene to detect A. spirocauda stages in seal lice. A. phagocytophilum and a Mycoplasma species previously identified from a patient with disseminated 'seal finger' mycoplasmosis were detected for the first time, to our knowledge, in seal lice.

CONCLUSIONS

Our findings support the potential vector role of seal lice in the transmission of A. spirocauda and reveal new insights into the spectrum of pathogens occurring in seal lice. Studies on vector competence of E. horridus, especially for bacterial pathogens, are essentially needed in the future as these pathogens might have detrimental effects on the health of seal populations. Furthermore, studies on the vector role of different echinophthiriid species infecting a wide range of pinniped hosts should be conducted to extend the knowledge of vector-borne pathogens.

Seal bites at sub-Antarctic Marion Island: Incidence, outcomes and treatment recommendations

Seal biologists at Marion Island (Southern Ocean) are in frequent contact with seals. During research activities, biologists may be bitten by seals, yet no standardised protocol for treating such bites is in place. Information on 22 seal bite cases at Marion Island was collected. Treatment of these bites varied, reflecting a need for standardised protocols for the treatment of bites. Recommendations for the in-field treatment of bites are presented. Five of the 22 cases had some symptoms which resembled ‘seal finger’ – a zoonotic infection, usually of the hands, that is contracted after a person comes into contact with tissues of seals or is bitten by one. However, in four of these cases, symptoms subsided within 4 days without antibiotic treatment; in the fifth case antibiotics were administered and symptoms subsided in 4 days. There is little evidence of the occurrence of seal finger at Marion Island, but this deserves further investigation.

Complete Sequence and Annotation of the Mycoplasma phocicerebrale Strain 1049T Genome

The Mycoplasma phocicerebrale genome was analyzed to better understand this opportunistic pathogen. Amplification with ϕ29 polymerase was used to generate enough genomic DNA for large-insert library construction. Like other mycoplasmas from seals, M. phocicerebrale encodes an immunosuppressor that may predispose susceptibility to infection or influence intercurrent diseases of affected hosts.

The Mycoplasma phocicerebrale genome was analyzed to better understand this opportunistic pathogen. Amplification with ϕ29 polymerase was used to generate enough genomic DNA for large-insert library construction. Like other mycoplasmas from seals, M. phocicerebrale encodes an immunosuppressor that may predispose susceptibility to infection or influence intercurrent diseases of affected hosts.

Pinnipediae

This chapter reviews common diseases of pinnipeds, including species in the Otariidae (fur seals and sea lions), Phocidae (true seals), and Odobenidae (walrus) families. Much of the knowledge on pathologic conditions of pinnipeds comes from necropsies of stranded animals and those housed in captivity. As such, disease knowledge is biased toward species frequently housed in zoos and aquaria, those that strand more commonly, or those in which free-ranging populations are more easily accessible. Though historically systematic evaluations of wild populations have rarely been accomplished, in the past 10 years, with advances in marine mammal medicine and anesthesia, biologists and veterinarians more frequently completed live animal health field investigations to evaluate health and disease in free-ranging pinniped populations.

Insights into the pathogenesis of Mycoplasma pneumoniae (Review)

Mycoplasma are the smallest prokaryotic microbes present in nature. These wall-less, malleable organisms can pass through cell filters, and grow and propagate under cell-free conditions in vitro. Of the pathogenic Mycoplasma Mycoplasma pneumoniae has been examined the most. In addition to primary atypical pneumonia and community-acquired pneumonia with predominantly respiratory symptoms, M. pneumoniae can also induce autoimmune hemolytic anemia and other diseases in the blood, cardiovascular system, gastrointestinal tract and skin, and can induce pericarditis, myocarditis, nephritis and meningitis. The pathogenesis of M. pneumoniae infection is complex and remains to be fully elucidated. The present review aimed to summarize several direct damage mechanisms, including adhesion damage, destruction of membrane fusion, nutrition depletion, invasive damage, toxic damage, inflammatory damage and immune damage. Further investigations are required for determining the detailed pathogenesis of M. pneumoniae.

Transformation of the genital epithelial tract occurs early in California sea lion development

An unusually high prevalence of metastatic urogenital carcinoma has been observed in free-ranging California sea lions stranded off the coast of California in the past two decades. No cases have been reported for sea lions in the relatively unpolluted Gulf of California. We investigated occurrence of genital epithelial transformation in 60 sea lions (n=57 pups and 3 adult females) from the Gulf of California and examined whether infection by a viral pathogen previously found to be associated with urogenital carcinoma accounted for such alterations. We also explored the contribution of MHC class II gene expression on transformation. Cellular alterations, such as squamous cell atypia (ASC), atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesions were observed in 42% of the pups and in 67% of the adult females. Normal genital epithelium was more common in male than female pups. ASC was five times more likely to occur in older pups. Epithelial alterations were unrelated to infection by the potentially oncogenic otarine type I gammaherpesvirus (OtHV-1), but ASCUS was more common in pups with marked and severe inflammation. Expression of MHC class II DRB loci (Zaca DRB-D) by peripheral antigen-presenting leucocytes showed a slightly 'protective' effect for ASC. We propose that transformation of the California sea lion genital epithelium is relatively common in young animals, increases with age and is probably the result of infection by an unidentified pathogen. Expression of a specific MHC class II gene, suggestive of presentation of specific antigenic peptides to immune effectors, appears to lower the risk of transformation. Our study provides the first evidence that epithelial transformation of the California sea lion genital tract is relatively common, even from an early age, and raises questions regarding differences in sea lion cancer-detection and -repair success between geographical regions.