ICTV Virus Taxonomy Profile: Arteriviridae 2021.

The family Arteriviridae comprises enveloped RNA viruses with a linear, positive-sense genome of approximately 12.7 to 15.7 kb. The spherical, pleomorphic virions have a median diameter of 50-74 nm and include eight to eleven viral proteins. Arteriviruses infect non-human mammals in a vector-independent manner. Infections are often persistent and can either be asymptomatic or produce overt disease. Some arteriviruses are important veterinary pathogens while others infect particular species of wild rodents or African non-human primates. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Arteriviridae, which is available at ictv.global/report/arteriviridae.

In situ hybridization and histopathological observations during ostreid herpesvirus-1-associated mortalities in Pacific oysters Crassostrea gigas.

In a previous longitudinal study conducted during a mortality investigation associated with ostreid herpesvirus-1 (OsHV-1) microvariant in New Zealand Pacific oysters in 2010-2011, temporality of OsHV-1 nucleic acid detection by real-time PCR assay and onset of Pacific oyster mortality was observed. The present study further elucidated the role of OsHV-1 using an in situ hybridization (ISH) assay on sections of Pacific oysters collected from the same longitudinal study. Hybridization of the labelled probe with the target region of the OsHV-1 genome in infected cells was detected colorimetrically using nitro blue tetrazolium (NBT). OsHV-1 presence and distribution in spat indicated by the ISH signal was then compared with the existence of pathological changes in oyster tissues. Dark blue to purplish black NBT cell labelling was seen predominantly in the stroma of the mantle and gills at Day 5 post introduction to the farm. The distribution and location of ISH signals indicated the extent of OsHV-1-infected cells in multiple tissues. Histopathological abnormalities were mostly non-specific; however, a progressive pattern of increasingly widespread haemocytosis coincided with the appearance of OsHV-1-infected cells in spat collected at different time-points. The visualisation of an increasing number of OsHV-1-positive cells in spat prior to a marked increase in mortality indicated the strong likelihood of an on-going and active viral infection in some oysters. Further studies are recommended to elucidate OsHV-1 pathogenesis in Pacific oysters in association with other potentially causal variables, such as elevated temperature and interaction with Vibrio spp. bacteria.

Genomic characterisation of canine papillomavirus type 17, a possible rare cause of canine oral squamous cell carcinoma.

Squamous cell carcinomas (SCCs) are the second most common cancer of the canine oral cavity resulting in significant morbidity and mortality. Recently a dog with multiple oral SCCs that contained a novel papillomavirus (PV) was reported. The aim of the present study was to determine the genome of this novel PV. To do this a short section of PV DNA was amplified from an oral SCC and 'back-to-back' primers were designed. Due to the circular nature of PV DNA, these primers were then used to amplify the remainder of the genome by inverse PCR. The PCR product was sequenced using next generation sequencing and the full genome of the PV, consisting of 8007 bp, was assembled and analysed. As this is the seventeenth PV identified from the domestic dog, the novel PV was designated Canis familiaris papillomavirus (CPV) type 17. Similar to other CPV types, the putative coding regions of CPV-17 were predicted to produce 5 early and 2 late proteins. Phylogenetic analysis of ORF L1 revealed greater than 70% similarity to CPV-2 and CPV-7 and we propose that CPV-17 also be classified as a Taupapillomavirus 1. While it appears CPV-17 is only rarely present in canine oral SCCs, evidence suggests that this PV could influence the development of oral SCCs in this species.

Genomic characterisation of the feline sarcoid-associated papillomavirus and proposed classification as Bos taurus papillomavirus type 14.

Feline sarcoids are rare mesenchymal neoplasms of domestic and exotic cats. Previous studies have consistently detected short DNA sequences from a papillomavirus (PV), designated feline sarcoid-associated papillomavirus (FeSarPV), in these neoplasms. The FeSarPV sequence has never been detected in any non-sarcoid sample from cats but has been amplified from the skin of cattle suggesting that feline sarcoids are caused by cross-species infection by a bovine papillomavirus (BPV). The aim of the present study was to determine the genome of the PV that contains the FeSarPV sequence. Using the circular nature of PV DNA, four specifically designed 'outward facing' primers were used to amplify two approximately 4,000 bp DNA segments from a feline sarcoid. The two PCR products were sequenced using next generation sequencing and the full genome of the PV, consisting 7,966 bp, was assembled and analysed. Phylogenetic analysis revealed the PV was closely related to the species 4 delta BPVs-1, -2, and -13, but distantly related to any carnivoran PV genus. These results are consistent with feline sarcoids being caused by a BPV type and we propose a classification of BPV-14 for this novel PV. Initial analysis suggests that, like other delta BPVs, the BPV-14 E5 protein could cause mesenchymal proliferation by binding to the platelet derived growth factor beta receptor. Interestingly BPV-14 has not been detected in any equine sarcoid suggesting that BPV-14 has a host range that is limited to bovids and felids.

Effects of physiologic concentrations of l-lysine on in vitro replication of feline herpesvirus 1.

OBJECTIVE: To evaluate the effects of various concentrations of l-lysine on in vitro replication of feline herpesvirus 1 (FHV-1). SAMPLE: Cultures of Crandell-Rees feline kidney (CRFK) cells. PROCEDURES: CRFK cells were inoculated with FHV-1 and maintained in media with 20 combinations of l-arginine and l-lysine concentrations. Changes in cell viability were monitored by continuous measurement of electrical impedance of cultured cells and by observation of viral cytopathic effects. Viral load was determined by use of quantitative PCR assay in supernatants obtained from infected cultures at specified time points. RESULTS: Increases in l-lysine concentration had no effect on the kinetics of cell death in FHV-1-infected cultures. There was also no significant effect (r(2) < 0.1) on viral DNA load for l-arginine concentrations ≥ 12 µg/mL There was a significant effect of increases in l-lysine concentration on viral DNA load in media supplemented with 6 µg of l-arginine/mL (mean ± SD slope, -4,641 ± 1,626 units; adjusted r(2) = 0.45). However, the difference between the lowest (1 × 10(6.28) copies/µL) and highest (1 × 10(6.86) copies/µL) FHV-1 DNA load in these media was < 1 logarithm. CONCLUSIONS AND CLINICAL RELEVANCE: The difference in FHV-1 DNA load was unlikely to be biologically important. Various l-lysine concentrations did not inhibit in vitro replication of FHV-1 at l-arginine concentrations sufficient to maintain cell growth. This conclusion was consistent with results of other studies in which investigators have not detected a consistently beneficial effect when l-lysine is administered to FHV-1-infected cats.

Comparison of the levels of Equus caballus papillomavirus type 2 (EcPV-2) DNA in equine squamous cell carcinomas and non-cancerous tissues using quantitative PCR.

Equus caballus papillomavirus type 2 (EcPV-2) infection has been associated with equine genital squamous cell carcinomas (SCCs). However, quantitative PCR (qPCR) has not been performed to determine viral copy numbers within these lesions. Additionally, the frequency with which EcPV-2 can be detected in other common sites of equine SCC development remains uncertain. The aim of this study was to develop a qPCR assay to estimate the viral load in a variety of equine tissue samples. These included 40 SCC lesions, 19 penile non-SCC or precursor disease lesions, and 222 tissues without observable lesions from SCC-prone sites on clinically normal horses. EcPV-2 DNA was present significantly more frequently, and in higher copy numbers, in equine penile SCC lesions than in either healthy penile mucosa or non-SCC penile lesions. This supports the hypothesis that EcPV-2 is involved in development of penile SCCs and suggests that penile EcPV-2 infection is rare in the absence of SCCs. Samples of normal vulval mucosa rarely contained EcPV-2 DNA and none of the nictitating membrane samples contained EcPV-2 DNA, indicating that asymptomatic EcPV-2 infection is uncommon at these sites. EcPV-2 DNA was detected in a proportion of both SCCs and normal samples from the oral cavity or pharynx, although there were no significant differences in the rate of infection or viral copy number between the SCCs and the normal mucosal samples. As such, the role of EcPV-2 in development of SCCs in this location remains to be established.

Genomic characterization of Felis catus papillomavirus-3: a novel papillomavirus detected in a feline Bowenoid in situ carcinoma.

There is increasing evidence that papillomaviruses (PVs) may cause skin cancer in cats. Neoplasms most frequently contain Felis domesticus PV type 2 (FdPV-2) DNA, but other PV DNA sequences have also been detected suggesting multiple PVs could cause disease. One of these sequences, FdPV-MY2, was previously detected in 5 of a series of 70 feline skin cancers. The aim was to determine the genome sequence of this PV. Using the circular nature of PV DNA, 'outward facing' primers specific for FdPV-MY2 were designed and amplified a 7300 bp length of DNA from a feline Bowenoid in situ carcinoma (BISC) that showed microscopic evidence of a viral etiology and tested positive for FdPV-MY2 DNA. The PCR product was sequenced using next generation sequencing technology. The full genomic sequence of the virus, comprising 7583 bp, was assembled and analyzed. As this is the third PV from a domestic cat, the virus was designated Felis catus PV type 3 (FcaPV-3). Consistent with other PVs, the putative coding regions of FcaPV-3 were predicted to produce 6 early proteins and 2 late ones. Classification was difficult as the virus contained over 60% nucleotide similarity within the ORF L1 with PVs from 3 different genera. However, based on phylogenetic analysis of ORF L1, FcaPV-3 was most closely related to the tau-PVs CPV-2 and CPV-7. As FcaPV-3 has over 60% nucleotide similarity with the ORF L1 of both tau-PVs, it is proposed that FcaPV-3 is classified in the genus Taupapillomavirus and is the first non-canine PV in this genus.

Evaluation of the effects of footwear hygiene protocols on nonspecific bacterial contamination of floor surfaces in an equine hospital.

OBJECTIVE: To evaluate the effects of footwear hygiene protocols on bacterial contamination of floor surfaces in an equine hospital. DESIGN: Field trial. PROCEDURES: Footwear hygiene protocols evaluated included use of rubber overboots with footbaths and footmats containing a quaternary ammonium disinfectant, rubber overboots with footbaths and footmats containing a peroxygen disinfectant, and no restrictions on footwear type but mandatory use of footbaths and footmats containing a peroxygen disinfectant. Nonspecific aerobic bacterial counts were determined via 2 procedures for sample collection and bacterial enumeration (contact plates vs swabbing combined with use of spread plates), and the effects of each footwear hygiene protocol were compared. RESULTS: There were no consistent findings suggesting that any of the protocols were associated with differences in numbers of bacteria recovered from floor surfaces. Although there were detectable differences in numbers of bacteria recovered in association with different footwear hygiene protocols, differences in least square mean bacterial counts did not appear to be clinically relevant (ie, were < 1 log10). CONCLUSIONS AND CLINICAL RELEVANCE: Although cleaning and disinfection of footwear are important aids in reducing the risk of nosocomial transmission of infectious agents in veterinary hospitals, the numbers of aerobic bacteria recovered from floor surfaces were not affected by use of rubber overboots or the types of disinfectant used in this study. Further study is warranted to evaluate the usefulness of footwear hygiene practices relative to their efficacy for reducing transmission of specific pathogens or decreasing nosocomial disease risk.

Efficacy of directed misting application of a peroxygen disinfectant for environmental decontamination of a veterinary hospital.

OBJECTIVE: To evaluate effectiveness of 4% peroxymonosulfate disinfectant applied as a mist to surfaces in a large animal hospital as measured by recovery of Staphylococcus aureus and Salmonella enterica serovar Typhimurium. DESIGN: Field trial. SAMPLE POPULATION: Polyester transparencies inoculated with bacteria. PROCEDURE: Polyester transparencies were inoculated with S aureus or S Typhimurium and placed in various locations in the hospital. After mist application of the peroxygen disinfectant, viable bacterial numbers were quantified and compared with growth from control transparencies to assess reduction in bacterial count. RESULTS: When applied as a mist directed at environmental surfaces contaminated with a geometric mean of 4.03 x 10(7) CFUs of S aureus (95% confidence interval [CI], 3.95 x 10(7) to 4.11 x 10(7)) or 6.17 x 10(6) CFUs of S Typhimurium (95% Cl, 5.55 x 10(6) to 6.86 x 10(6)), 4% peroxymonosulfate reduced the geometric mean number of viable S aureus by 3.04 x 10(7) CFUs (95% Cl, 8.6 x 10(5) to 1.7 x 10(6)) and S Typhimurium by 3.97 x 10(6) CFUs (95% Cl, 8.6 x 10(5) to 3.5 x 10(6)). CONCLUSIONS AND CLINICAL RELEVANCE: Environmental disinfection with directed mist application of a 4% peroxymonosulfate solution was successful in reducing counts of bacterial CFUs by > 99.9999%. Directed mist application with this peroxygen disinfectant as evaluated in this study appeared to be an effective and efficient means of environmental disinfection in a large animal veterinary hospital and would be less disruptive than more traditional approaches to intensive environmental cleaning and disinfection.

An overview of infection control strategies for equine facilities, with an emphasis on veterinary hospitals.

Infection control entails preventing or minimizing exposure to infectious agents or optimizing resistance to infection at the individual and population levels should exposure occur. The degree to which each of these strategies is applied varies according to the attributes of the disease agent and the population at risk. In developing an infection control, biosecurity, or biocontainment plan, it is important to decide which agent or agents are to be controlled, the method by which they might be introduced to the individual or population, and methods by which they might spread once at a farm or veterinary clinic.