Equine Arteritis Virus Derived from an Infectious cDNA Clone Is Attenuated and Genetically Stable in Infected Stallions

Abstract

Virus derived from an infectious cDNA clone of equine arteritis virus (EAV030H) was intranasally inoculated into two stallions, neither of which subsequently developed clinical manifestations of equine viral arteritis (EVA). Virus was isolated from nasal swabs and mononuclear cells collected from both stallions </=14 days p.i. and from the semen of one stallion only at 7 days p.i. Similarly, viral RNA was detected by RT nested-PCR in nasal swabs and mononuclear cells for </=14 days p.i. and at 7 days p.i. in the semen of the one stallion. Both stallions seroconverted to EAV by 10 days p.i. and maintained high neutralizing antibody titers thereafter. Sequence and restriction digestion analysis demonstrated that the recombinant virus present in nasal swabs, mononuclear cells, and semen from the two stallions was identical to the infectious clone-derived virus that was used to inoculate them. Furthermore analysis of multiple clones derived by RT nested-PCR amplification from several samples indicated that the recombinant EAV030H virus was stable during replication in horses. These studies document for the first time that a recombinant virus derived from an infectious cDNA clone of a member of the order Nidovirales is replication competent in animals, and the genetic stability of the recombinant virus during in vivo replication indicates that it will be useful for the characterization of genetic determinants of virulence and persistence of EAV. The genetic conservation of the cloned recombinant virus during in vivo infection is similar to that which occurs during natural horizontal and vertical transmission of EAV in horses and contrasts with the heterogeneous virus population (quasispecies) that occurs in the semen of carrier stallions.

Detection Of Equine Arteritis Virus In The Semen Of Stallions In The Republic Of Serbia

“…The presence of EAV-specifi c antibodies in the horse blood serum is one of the evidence of the presence of the disease, which has been confi rmed also in our study by fi ndings of high antibody titre values in breeding stallions and mares [6,12,14]. High antibody titre and seroprevalence in stallions (45%) and mares (65%), without clinical signs strongly suggest the long-lasting presence of the disease at a horse stable [8].…”

“…The fi rst anti-EAV antibodies can be detected 7-14 days after infection. The highest levels of antibodies are detectable in the period 2-4 months post infection, and they can persist for 3 or more years [6,12]. Antibody titre values higher than 2 log 2 are considered positive in VNT [13].…”

Complex Interactions between the Major and Minor Envelope Proteins of Equine Arteritis Virus Determine Its Tropism for Equine CD3+T Lymphocytes and CD14+Monocytes

“…The virus infects the smaller blood vessels, especially the arterioles, causing a panvasculitis (16,35,42). A number of studies have demonstrated that different strains of EAV vary significantly in their pathogenicity, with very different clinical outcomes upon experimental inoculation of horses (2,5,6,21,43). The horseadapted virulent Bucyrus (VB) strain of EAV is highly velogenic and causes severe clinical disease with a case fatality rate of 50 to 60% under experimental conditions (35,51).…”

“…Horses inoculated with virulent strains of EAV (e.g., the VB, recombinant VB [rVBS], and KY84 strains) develop severe lymphopenia with a high-titer viremia (6 ϫ 10 3 to 1 ϫ 10 5 PFU/ml) (2,5,35,44). In contrast, horses inoculated with the attenuated modified live virus (MLV) vaccine strain or other avirulent strains of EAV (e.g., 030H and CA95G) (6,49) develop a mild, transient lymphopenia with only a very-low-titer viremia (Յ1 ϫ 10 1 PFU/ml) (20,24,(37)(38)(39)(40). The MLV vaccine (ARVAC; Fort Dodge Animal Health, Fort Dodge, IA) that is in current use in the United States and Canada (20,(37)(38)(39)(40) (24).…”

An infectious cDNA clone of a highly pathogenic porcine reproductive and respiratory syndrome virus variant associated with porcine high fever syndrome

“…Reverse genetic systems are a powerful tool for the molecular dissection of arteriviruses and infectious cDNA clones have been developed for equine arteritis virus and traditional PRRSV strains (Balasuriya et al, 1999(Balasuriya et al, , 2007Meulenberg et al, 1998;van Dinten et al, 1997;Wang et al, 2008). In this study, we set out to construct infectious cDNA clones of HP PRRSV to further clarify the role of this virus as the major aetiological agent of PHFS.…”