Cardiac Rhabdomyoma in Four Göttingen Minipigs.

Göttingen minipigs are increasingly used as an alternative large animal model in nonclinical toxicology studies, and proliferative lesions in this species are rare. Here, we report four cases of cardiac rhabdomyoma in Göttingen minipigs, an incidental and benign mass in the heart. Three cases lacked gross observations and had a microscopic nodule in either the left ventricle or interventricular septum. The last case had a large, firm, raised nodule on a left ventricular papillary muscle noted at necropsy, with additional microscopic intramural masses in the left ventricular wall. In all cases, microscopic evaluation revealed well-circumscribed, expansile nodules composed of bundles of large, highly vacuolated, ovoid to polygonal cells with variable cytoplasmic processes radiating from a centrally located nucleus. Cells displayed patchy accumulation of intracytoplasmic, PAS-positive material and haphazardly arranged cytoplasmic cross-striations. There was no evidence of cardiac insufficiency or other data to suggest the masses were clinically meaningful. Cardiac rhabdomyomas have been reported in meat-hybrid swine, with a breed predisposition in red wattle. This lesion is well established in guinea pigs, but documentation in other laboratory species used in toxicologic studies is limited to two beagle dogs. To our knowledge, this is the first report of spontaneous cardiac rhabdomyoma in Göttingen minipigs.

Idiopathic Aneurysms of the Ascending Aorta in the Mouse and Rat.

Aneurysms of the ascending aorta, unrelated to xenobiotic administration, are described in 5 rats and 2 mice in nonclinical safety studies conducted at Charles River Laboratories (CRL) sites over the past 10 years. The most prominent microscopic finding was focal dilation with disruption of the wall of the ascending aorta with chronic adventitial inflammation or fibroplasia. The pathogenesis of this finding is unknown. There were no associated macroscopic findings, clinical abnormalities, or vascular lesions elsewhere. The results of a search of historical control data from toxicology studies of 1 day to 72 weeks' duration performed at CRL for aortic findings from 5900 mice and 23,662 rats are also reported. Aortic lesions are uncommon in mice and rats used in nonclinical safety studies, but toxicologic pathologists should be aware that aneurysms of the ascending aorta with fibroplasia and inflammation in the aortic wall and adventitia may occur spontaneously or iatrogenically, as they have the potential to impact interpretation in toxicology studies.

Inhibition of an Aquatic Rhabdovirus Demonstrates Promise of a Broad-Spectrum Antiviral for Use in Aquaculture.

Many enveloped viruses cause devastating disease in aquaculture, resulting in significant economic impact. LJ001 is a broad-spectrum antiviral compound that inhibits enveloped virus infections by specifically targeting phospholipids in the lipid bilayer via the production of singlet oxygen (1O2). This stabilizes positive curvature and decreases membrane fluidity, which inhibits virus-cell membrane fusion during viral entry. Based on data from previous mammalian studies and the requirement of light for the activation of LJ001, we hypothesized that LJ001 may be useful as a preventative and/or therapeutic agent for infections by enveloped viruses in aquaculture. Here, we report that LJ001 was more stable with a prolonged inhibitory half-life at relevant aquaculture temperatures (15°C), than in mammalian studies at 37°C. When LJ001 was preincubated with our model virus, infectious hematopoietic necrosis virus (IHNV), infectivity was significantly inhibited in vitro (using the epithelioma papulosum cyprini [EPC] fish cell line) and in vivo (using rainbow trout fry) in a dose-dependent and time-dependent manner. While horizontal transmission of IHNV in a static cohabitation challenge model was reduced by LJ001, transmission was not completely blocked at established antiviral doses. Therefore, LJ001 may be best suited as a therapeutic for aquaculture settings that include viral infections with lower virus-shedding rates than IHNV or where higher viral titers are required to initiate infection of naive fish. Importantly, our data also suggest that LJ001-inactivated IHNV elicited an innate immune response in the rainbow trout host, making LJ001 potentially useful for future vaccination approaches. IMPORTANCE: Viral diseases in aquaculture are challenging because there are few preventative measures and/or treatments. Broad-spectrum antivirals are highly sought after and studied because they target common components of viruses. In our studies, we used LJ001, a broad-spectrum antiviral compound that specifically inhibits enveloped viruses. We used the fish rhabdovirus infectious hematopoietic necrosis virus (IHNV) as a model to study aquatic enveloped virus diseases and their inhibition. We demonstrated inhibition of IHNV by LJ001 both in cell culture as well as in live fish. Additionally, we showed that LJ001 inhibited the transmission of IHNV from infected fish to healthy fish, which lays the groundwork for using LJ001 as a possible therapeutic for aquatic viruses. Our results also suggest that virus inactivated by LJ001 induces an immune response, showing potential for future preventative (e.g., vaccine) applications.

Broad-spectrum antiviral JL122 blocks infection and inhibits transmission of aquatic rhabdoviruses.

The aquaculture industry is growing rapidly to meet the needs for global protein consumption. Viral diseases in aquaculture are quite challenging due to lack of treatment options as well as limited injection-delivery vaccines, which are costly. Thus, water-immersion antiviral treatments are highly desirable. This study focused on broad-spectrum, light-activated antivirals that target the viral membrane (envelope) of viruses to prevent viral-cell membrane fusion, ultimately blocking viral entry into cells. Of the tested small-molecules, JL122, a new broad-spectrum antiviral previously unexplored against aquatic viruses, blocked infection of three aquatic rhabdoviruses (IHNV, VHSV and SVCV) in cell culture and in two live fish challenge models. Importantly, JL122 inhibited transmission of IHNV from infected to uninfected rainbow trout. Further, the effective antiviral concentrations were not toxic to cells or susceptible fish. These results show promise for JL122 to become an immersion treatment option for outbreaks of aquatic enveloped viral infections.

Discovery of a novel, monocationic, small-molecule inhibitor of scrapie prion accumulation in cultured sheep microglia and Rov cells.

Prion diseases, including sheep scrapie, are neurodegenerative diseases with the fundamental pathogenesis involving conversion of normal cellular prion protein (PrP(C)) to disease-associated prion protein (PrP(Sc)). Chemical inhibition of prion accumulation is widely investigated, often using rodent-adapted prion cell culture models. Using a PrP(Sc)-specific ELISA we discovered a monocationic phenyl-furan-benzimidazole (DB772), which has previously demonstrated anti-pestiviral activity and represents a chemical category previously untested for anti-prion activity, that inhibited PrP(Sc) accumulation and prion infectivity in primary sheep microglial cell cultures (PRNP 136VV/154RR/171QQ) and Rov9 cultures (VRQ-ovinized RK13 cells). We investigated potential mechanisms of this anti-prion activity by evaluating PrP(C) expression with quantitative RT-PCR and PrP ELISA, comparing the concentration-dependent anti-prion and anti-pestiviral effects of DB772, and determining the selectivity index. Results demonstrate at least an approximate two-log inhibition of PrP(Sc) accumulation in the two cell systems and confirmed that the inhibition of PrP(Sc) accumulation correlates with inhibition of prion infectivity. PRNP transcripts and total PrP protein concentrations within cell lysates were not decreased; thus, decreased PrP(C) expression is not the mechanism of PrP(Sc) inhibition. PrP(Sc) accumulation was multiple logs more resistant than pestivirus to DB772, suggesting that the anti-PrP(Sc) activity was independent of anti-pestivirus activity. The anti-PrP(Sc) selectivity index in cell culture was approximately 4.6 in microglia and 5.5 in Rov9 cells. The results describe a new chemical category that inhibits ovine PrP(Sc) accumulation in primary sheep microglia and Rov9 cells, and can be used for future studies into the treatment and mechanism of prion diseases.