Modulation of host lipid metabolism by virus infection leads to exoskeleton damage in shrimp.

The arthropod exoskeleton provides protection and support and is vital for survival and adaption. The integrity and mechanical properties of the exoskeleton are often impaired after pathogenic infection; however, the detailed mechanism by which infection affects the exoskeleton remains largely unknown. Here, we report that the damage to the shrimp exoskeleton is caused by modulation of host lipid profiles after infection with white spot syndrome virus (WSSV). WSSV infection disrupts the mechanical performance of the exoskeleton by inducing the expression of a chitinase (Chi2) in the sub-cuticle epidermis and decreasing the cuticle chitin content. The induction of Chi2 expression is mediated by a nuclear receptor that can be activated by certain enriched long-chain saturated fatty acids after infection. The damage to the exoskeleton, an aftereffect of the induction of host lipogenesis by WSSV, significantly impairs the motor ability of shrimp. Blocking the WSSV-caused lipogenesis restored the mechanical performance of the cuticle and improved the motor ability of infected shrimp. Therefore, this study reveals a mechanism by which WSSV infection modulates shrimp internal metabolism resulting in phenotypic impairment, and provides new insights into the interactions between the arthropod host and virus.

The role of Virus "X" (Tortoise Picornavirus) in kidney disease and shell weakness syndrome in European tortoise species determined by experimental infection.

Tortoise Picornavirus (ToPV) commonly known as Virus "X" was recently discovered in juvenile European tortoises suffering from soft carapace and plastron as well as kidney disease. Therefore, this virus was a potential candidate to be a causative agent for these disease patterns. Spur thighed tortoises (Testudo graeca) seemed to be more susceptible to establish clinical symptoms than other European species like T. hermanni. Thus this trial investigated the role of ToPV in the described syndrome. Two groups of juvenile European tortoises (T. graeca and T.hermanni) each of 10 animals, were cloacally, oronasally and intracoelomically inoculated with an infectious dose (~ 2000 TICD) of a ToPV strain isolated from a diseased T. graeca. A control group of two animals of each species received non-infected cell culture supernatant. The tortoises were examined daily and pharyngeal and cloacal swabs for detection of ToPV-RNA by RT-PCR were taken from each animal every six days for a period of 6 months. At the end of the study the remaining animals were euthanised and dissected. Bacteriological and parasitological tests were performed and organ samples of all tortoises were investigated by RT-PCR for the presence of ToPV and histopathology. Animals that were euthanised at the end of the experiment, were examined for presence of specific anti-ToPV antibodies. Several animals in both inoculated groups showed retarded growth and a light shell weakness, in comparison to the control animals. Three animals were euthanised during the trial, showing reduced weight gain, retarded growth, severe shell weakness and apathy, in parallel to clinical observations in naturally infected animals. In all inoculated animals of both species an intermittent virus shedding, starting from 18 days post inoculation (d.p.i.), till 164 d.p.i. was detected, while the control animals remained negative. The virus was successfully reisolated in terrapene heart cell culture in 16 of 20 inoculated animals of both species. Histopathology of most inoculated animals revealed a lack of bone remodeling and vacuolisation in kidney tubuli which supports the described pathogenesis of nephropathy and osteodystrophy. Anti- ToPV antibody titres ranged from 1:2 to >1:256 in 13 of 20 animals, whereas all control animals were seronegative. The study proofed the Henle Koch`s postulates of ToPV as causative agent for shell dystrophy and kidney disease in both testudo species. The proposed species specific sensitivity towards clinical disease was not observed.

DETECTION OF RANAVIRUS USING BONE MARROW HARVESTED FROM MORTALITY EVENTS IN EASTERN BOX TURTLES ( TERRAPENE CAROLINA CAROLINA).

The causes of free-living chelonian mortality events are often unknown because of infrequent recovery of remains and rapid postmortem decomposition. This study describes a technique to harvest bone marrow and detect frog virus 3-like ranavirus (FV3) using quantitative polymerase chain reaction in skeletonized eastern box turtles ( Terrapene carolina carolina) ( N = 87), and assesses agreement with concurrent perimortem samples ( N = 14). FV3 was detected in bone marrow samples from 12 turtle shells (14%). Three of 14 turtles had detectable FV3 loads in both bone marrow and perimortem samples, two turtles had detectable FV3 in bone marrow only, and nine turtles tested FV3 negative in both bone marrow and concurrent perimortem samples. There was substantial agreement between FV3 testing of bone marrow and other tissues ( κ = 0.658). Harvesting bone marrow from shells is easily performed and can serve as a means for biologists and wildlife veterinarians to improve postmortem surveillance for systemically distributed pathogens, including FV3.

Disease, parasite, and commensal prevalences for blue crab Callinectes sapidus at shedding facilities in Louisiana, USA.

Blue crab diseases, parasites, and commensals are not well studied in the Gulf of Mexico, and their prevalence rates have only been sporadically determined. Commercial soft shell shedding facilities in Louisiana experience high mortality rates of pre-molt crabs, and some of these deaths may be attributable to diseases or parasites. During the active shedding season in 2013, we determined the prevalence of shell disease, Vibrio spp., Lagenophrys callinectes, and Hematodinium perezi at 4 commercial shedding facilities along the Louisiana coast. We also detected Ameson michaelis and reo-like virus infections. Shell disease was moderately prevalent at rates above 50% and varied by shedding facility, collection month, and crab size. Vibrio spp. bacteria were prevalent in the hemolymph of 37% of the pre-molt crabs. Lagenophrys callinectes was highly prevalent in the pre-molt crabs, but because it is a commensal species, it may not cause high mortality rates. Hematodinium perezi was absent in all pre-molt crabs.

Herpesvirus in a captive Australian Krefft's river turtle (Emydura macquarii krefftii).

CASE REPORT: A mature, captive Krefft's river turtle (Emydura macquarii krefftii) was presented with severe proliferative and ulcerative lesions of the skin and shell. The areas were biopsied and histopathological examination demonstrated orthokeratotic hyperkeratosis with keratinocytes containing eosinophilic intranuclear inclusions. Molecular diagnostics confirmed the presence of a herpesvirus in the affected tissues. CONCLUSION: This is the first recorded case of herpesvirus infection in an Australian freshwater turtle species.

Soft plastron, soft carapace with skeletal abnormality in juvenile tortoises. Histopathology and isolation of a novel picornavirus from Testudo graeca and Geochelone elegans.

OBJECTIVE: A disease is described in juvenile tortoises (Testudo graeca and Geochelone elegans) consisting mainly of a soft carapace, soft plastron and deformed skeleton. The aim of this study was to determine histopathological lesions and the biological properties of the isolated viruses. MATERIALS AND METHODS: Clinical signs and gross pathology were determined on diseased and healthy appearing tortoises. Paraffin sections were stained with HE, PAS and Prussian Blue and histologically examined. Terrapene heart (TH-1) cell cultures served for virus isolations from 64 tissues and 104 swabs. One isolate (isolate 1243/37 tongue) was used in neutralization tests on 19 sera. RESULTS: Retarded growth and increasingly soft plastron and carapace were the prominent signs in diseased tortoises. Pathological lesions consisted of dilated urinary sac, enlarged kidneys and livers. Histopathologically, hepatic hemosiderosis, hypoplastic anaemia, congestive glomerulonephrosis and osteodystrophy were seen. A novel vi- rus ("virus X") was isolated from 64 organs and 79 of 104 swabs. The isolated viruses were identified as a novel chelonid picornavirus based on cytopathic effect, resistance to chloroform and stability at low pH. Co-cultivation with 5-iodo-2'-deoxyuridine and actinomycin D did not reduce virus titres. Electron microscopically, round, non-enveloped particles (25-30 nm) were detected. Neutralizing antibodies to the isolate 1243/37tongue were present in 17 of 19 sera from seven species of tortoises. CONCLUSION AND CLINICAL RELEVANCE: Nephropathy, osteodystrophy and virus isolations suggest a viral aetiology. Metabolic bone disease is the major differential diagnosis. Further investigations in vivo are needed to evaluate the likely effects of the picornavirus on tortoises.