Vesicular stomatitis and other vesicular, erosive, and ulcerative diseases of horses

Identification of a Novel α-herpesvirus Associated with Ulcerative Stomatitis in Donkeys

An outbreak of ulcerative stomatitis was observed in a donkey (Equus asinus) dairy herd. Similar lesions were also observed on the dams’ udders and, sporadically, in genital areas. The lesions typically resolved in 1–3 weeks. An α-herpesvirus, Varicellovirus, genetically related to equid herpesvirus type 3, was identified.

Complete genome sequence of Piry vesiculovirus

Piry virus (PIRYV) is a rhabdovirus (genus Vesiculovirus) and is described as a possible human pathogen, originally isolated from a Philander opossum trapped in Para State, Northern Brazil. This study describes the complete full coding sequence and the genetic characterization of PIRYV. The genome sequence reveals that PIRYV has a typical vesiculovirus-like organization, encoding the five genes typical of the genus. Phylogenetic analysis confirmed that PIRYV is most closely related to Perinet virus and clustered in the same clade as Chandipura and Isfahan vesiculoviruses.

In Vivo Replication and Pathogenesis of Vesicular Stomatitis Virus Recombinant M40 Containing Ebola Virus L-Domain Sequences

The M40 VSV recombinant was engineered to contain overlapping PTAP and PPxY L-domain motifs and flanking residues from the VP40 protein of Ebola virus. Replication of M40 in cell culture is virtually indistinguishable from that of control viruses. However, the presence of the Ebola PTAP motif in the M40 recombinant enabled this virus to interact with and recruit host Tsg101, which was packaged into M40 virions. In this brief report, we compared replication and the pathogenic profiles of M40 and the parental virus M51R in mice to determine whether the presence of the Ebola L-domains and flanking residues altered in vivo characteristics of the virus. Overall, the in vivo characteristics of M40 were similar to those of the parental M51R virus, indicating that the Ebola sequences did not alter pathogenesis of VSV in this small animal model of infection.

Characterization of the temporal and spatial distribution and reproductive ratio of vesicular stomatitis outbreaks in Mexico in 2008

OBJECTIVE

To characterize the temporal and spatial distribution and reproductive ratio of vesicular stomatitis (VS) outbreaks reported in Mexico in 2008.

ANIMALS

Bovine herds in Mexico in which VS outbreaks were officially reported and confirmed from January 1 through December 31, 2008.

PROCEDURES

The Poisson model of the space-time scan statistic was used to identify periods and geographical locations at highest risk for VS in Mexico in 2008. The herd reproductive ratio (R(h)) of the epidemic was computed by use of the doubling-time method.

RESULTS

1 significant space-time cluster of VS was detected in the state of Michoacan from September 4 through December 10, 2008. The temporal extent of the VS outbreaks and the value and pattern of decrease of the R(h) were different in the endemic zone of Tabasco and Chiapas, compared with findings in the region included in the space-time cluster.

CONCLUSIONS AND CLINICAL RELEVANCE

The large number of VS outbreaks reported in Mexico in 2008 was associated with the spread of the disease from the endemic zone in southern Mexico to areas sporadically affected by the disease. Results suggested that implementation of a surveillance system in the endemic zone of Mexico aimed at early detection of changes in the value of R(h) and space-time clustering of the disease could help predict occurrence of future VS outbreaks originating from this endemic zone. This information will help prevent VS spread into regions of Mexico and neighboring countries that are only sporadically affected by the disease.

Equid Herpesvirus 2-Associated Oral and Esophageal Ulceration in a Foal

A case of a 1-month-old Thoroughbred foal with dysphagia, salivation, pyrexia, oral mucosal pustules, and esophageal ulceration is reported. Swabs from the ulcerated lesions yielded Equid herpesvirus 2 (EHV-2) in virus isolation assays, and histopathology of a biopsy from the esophageal lesion identified nuclear inclusions suggestive of herpesviruses. Immunohistochemical staining with antibodies specific for EHV-2 was positive for epithelial cells in the vicinity of the ulcer but not in more distant mucosa. Electron microscopic evaluation of the biopsy showed herpesviral particles in epithelial cells. The foal recovered over 5 days of supportive and gastroprotective therapy, and the esophageal ulcers healed. Serology and immunohistochemistry indicated that this foal likely had lesions associated with EHV-2 and not EHV-1, −4, or −5.

Assessment of the viral safety of antivenoms fractionated from equine plasma

Antivenoms are preparations of intact or fragmented (F(ab′)₂ or Fab) immunoglobulin G (IgG) used in human medicine to treat the severe envenomings resulting from the bites and stings of various animals, such as snakes, spiders, scorpions, or marine animals, or from the contact with poisonous plants. They are obtained by fractionating plasma collected from immunized horses or, less frequently, sheep. Manufacturing processes usually include pepsin digestion at acid pH, papain digestion, ammonium sulphate precipitation, caprylic acid precipitation, heat coagulation and/or chromatography. Most production processes do not have deliberately introduced viral inactivation or removal treatments, but antivenoms have never been found to transmit viruses to humans. Nevertheless, the recent examples of zoonotic diseases highlight the need to perform a careful assessment of the viral safety of antivenoms.

This paper reviews the characteristics of equine viruses of antivenoms and discusses the potential of some manufacturing steps to avoid risks of viral contamination. Analysis of production parameters indicate that acid pH treatments and caprylic acid precipitations, which have been validated for the manufacture of some human IgG products, appear to provide the best potential for viral inactivation of antivenoms. As many manufacturers of antivenoms located in developing countries lack the resources to conduct formal viral validation studies, it is hoped that this review will help in the scientific understanding of the viral safety factors of antivenoms, in the controlled implementation of the manufacturing steps with expected impact on viral safety, and in the overall reinforcement of good manufacturing practices of these essential therapeutic products.

A single-tube multiplex reverse transcription-polymerase chain reaction for detection and differentiation of vesicular stomatitis Indiana 1 and New Jersey viruses in insects

A multiplex single-tube reverse transcription-polymerase chain reaction (RT-PCR) has been developed for the detection and differentiation of vesicular stomatitis viruses (VSV), Indiana 1 and New Jersey, from insect samples. Using this assay, detection of either or both viruses in as little as 20 fg of total RNA from tissue culture was achieved, along with detection of vesicular stomatitis (VS) RNA from macerates containing 2 infected mosquitoes in pools of 10-30 noninfected mosquitoes. Vesicular stomatitis virus was detected by RT-PCR in all culture-positive samples, and detection as low as 4 plaque forming units per milliliter was achieved. Comparison between RT-PCR and tissue culture revealed that RT-PCR was able to detect VSV in a volume of insect macerate averaging almost 100 times less than that required for detection by tissue culture. The reported RT-PCR is a potential valuable tool for rapid and sensitive detection and differentiation of VS in insects because intense work associated with viral isolation, the cytotoxicity of insect extracts, and separate virus identification steps can be avoided. Potential application to detection and differentiation of VSV serotypes from vertebrate hosts is addressed.