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Tissue samples from Australian carpet pythons (Morelia spilota) with neurological disease were screened for viruses using next-generation sequencing. Coding complete genomes of two bornaviruses were identified with the gene order 3’-N-X-P-G-M-L, representing a transposition of the G and M genes compared to other bornaviruses and most mononegaviruses. Use of these viruses to search available vertebrate genomes enabled recognition of further endogenous bornavirus-like elements (EBLs) in diverse placental mammals, including humans. Codivergence patterns and shared integration sites revealed an ancestral laurasiatherian EBLG integration (77 million years ago [MYA]) and a previously identified afrotherian EBLG integration (83 MYA). The novel python bornaviruses clustered more closely with these EBLs than with other exogenous bornaviruses, suggesting that these viruses diverged from previously known bornaviruses prior to the end-Cretaceous (K-Pg) extinction, 66 MYA. It is possible that EBLs protected mammals from ancient bornaviral disease, providing a selective advantage in the recovery from the K-Pg extinction. A degenerate PCR primer set was developed to detect a highly conserved region of the bornaviral polymerase gene. It was used to detect 15 more genetically distinct bornaviruses from Australian pythons that represent a group that is likely to contain a number of novel species. [ABSTRACT FROM AUTHOR]

As part of a larger investigation into three emerging disease syndromes highlighted by conjunctivitis and pharyngitis, systemic lymphoid proliferation and encephalitis, and lymphonodular skin infiltrates in farmed saltwater crocodiles ( Crocodylus porosus ) and one emerging syndrome of systemic lymphoid proliferation in captive freshwater crocodiles ( Crocodylus johnstoni ), cytopathic effects (CPE), including syncytial cell formation, were observed in primary crocodile cell lines exposed to clarified tissue homogenates from affected crocodiles. Ten cell cultures with CPE were then screened for herpesviruses using two broadly-reactive herpesvirus PCRs. Amplicons were obtained from 9 of 10 cell cultures and were sequenced. Three novel herpesviruses were discovered and the phylogenetic analysis of these viruses showed there was a 63% Bayesian posterior probability value supporting these viruses clustering with the subfamily Alphaherpesvirinae , and 100% posterior probability of clustering with a clade containing the Alphaherpesvirinae and other unassigned reptile herpesviruses. It is proposed that they are named Crocodyline herpesvirus (CrHV) 1, 2 and 3. CrHV1 and 2 were only isolated from saltwater crocodiles and CrHV3 was only isolated from freshwater crocodiles. A duplex PCR was designed that was able to detect these herpesviruses in formalin-fixed paraffin-embedded tissues, a sample type that neither of the broadly-reactive PCRs was able to detect these herpesviruses in. This work describes the isolation, molecular detection and phylogeny of these novel herpesviruses but the association that they have with the emerging disease syndromes requires further investigation. [ABSTRACT FROM AUTHOR]

An aquatic animal faces challenges not encountered by its terrestrial counterparts, promoting adaptive responses in multiple traits. For example, a thicker dermis might protect snakes when they are pushed against sharp objects by water currents, and might enable a snake to shed fouling organisms attached to its skin. We thus predicted that marine snakes should have thicker skin than terrestrial species, and that smaller sea snakes should have relatively thicker skin (because absolute, not relative, thickness determines vulnerability to fouling). Measurements of 192 snakes of 44 species supported those predictions. Many (but not all) sea snakes have skins 50% thicker than those of terrestrial and amphibious snake species, representing multiple independent evolutionary origins of thicker skin (in acrochordids, Laticauda sea kraits and both main clades of hydrophiine sea snakes). Marine snakes showed different allometries of skin thickness compared with their terrestrial counterparts; larger snakes had thicker skin within and among species of amphibious and terrestrial snakes, but larger aquatic snake species had thinner skin compared with smaller taxa. Interspecific variation in skin thickness was primarily due to increased collagen in the deep dermis, a physical barrier well suited to protecting against physical injury and to resisting penetration by epibionts. [ABSTRACT FROM AUTHOR]

At an invasion front, energetic and physiological trade-offs may differ from those at the range-core as a result of selection for enhanced dispersal, combined with a low density of conspecifics (which reduces pathogen transmission and competition for food). We measured traits related to energy stores and immunity in wild cane toads ( Rhinella marina) across a 750-km transect from their invasion front in tropical Australia, back into sites colonized 21 years earlier. Several traits were found to vary with population age; some linearly and others in a curvilinear manner. The relative size of spleens and fat bodies was highest in the oldest and newest populations, where rates of lungworm infection were lowest. Toads from older populations produced more corticosterone in response to a standardized stressor, and had higher lymphocyte counts (but lower basophil counts). The amount of skin swelling elicited by phytohaemagglutinin injection did not vary geographically, although recruitment of leukocytes to the injected tissue was higher in toads from long-colonized areas. Because this was a field-based study, we cannot differentiate the effects of population age, toad density or pathogen pressure on our measures of stress and immune responses, nor can we distinguish whether the causation involves hard-wired adaptive processes or phenotypically plastic responses. Nonetheless, our data demonstrate substantial variation in immune systems among toads at varying distances from an invasion front, showing that a biological invasion imposes strong pressures on physiological systems of the invader. [ABSTRACT FROM AUTHOR]

Highlights • The impact of known crocodilian skin pathogens including viral, bacterial, fungal and helminth taxa are reviewed. • Best husbandry practices to minimise these pathogens are discussed. • Husbandry improvements, such as heating, have already seen a reduced incidence in many of these pathogens. • Viral pathogens are the largest risk to crocodilian skin quality and require more than improved husbandry practices. Abstract The control of pathogens that target crocodilian skin is essential to the long-term success and sustainability of intensive farming operations worldwide. To understand the impact these pathogens may have on the skin, a brief overview of skin histology is given. A review of the known viral, bacterial, fungal and helminth taxa associated with skin conditions in commercially significant crocodilian species is presented. Best management practices are discussed, with an emphasis on addressing extrinsic factors that influence transmission and pathogenicity. It is argued that, in the past, reduced immune function arising from inadequate thermal regulation was the leading cause of skin disease in captive crocodilians. Consequently, innovations such as temperature control, coupled with the adoption of more stringent hygiene standards, have greatly reduced the prevalence of many infectious skin conditions in intensively farmed populations. However, despite improvements in animal husbandry and disease management, viral pathogens such as West Nile virus, herpesvirus and poxvirus continue to afflict crocodilians in modern captive production systems. [ABSTRACT FROM AUTHOR]

Specific pathways of the ecological impact of invasive species remain poorly known. Although the spread of toxic cane toads (Bufo marinus) through tropical Australia is widely believed to have caused extensive mortality of native reptiles and mammals, effects of toad ingestion on native anurans have been virtually ignored. Our studies on the Adelaide River floodplain show that the most numerous vertebrate victims of toad invasion are native tadpoles that die when they attempt to consume toad eggs. We documented 11 episodes of mass mortality, totalling >1300 tadpoles of 10 species, in five waterbodies within a single wet-season shortly after the toads invaded. A causal link between toad breeding and tadpole mortality is supported by observations that: (1) in at least 9 of the 11 waterbodies involved, toads bred immediately prior to mortality events; (2) water quality was indistinguishable from that of control ponds, and tadpoles placed in that water remained healthy; (3) dead tadpoles showed no sign of disease; and (4) laboratory trials showed rapid, 100% mortality in native tadpoles exposed to freshly-laid toad eggs. Despite these high mortality rates, toad invasion does not appear to threaten the viability of anuran populations because frogs often breed in ponds not used by toads, and because density-dependent growth and survival within tadpole communities mean that additional mortality may not reduce the total effective recruitment of metamorph frogs from a waterbody. [Copyright &y& Elsevier]