Isolation and Partial Sequencing ofEquid Herpesvirus 5from a Horse in Iceland

Abstract

Abstract. Horses are hosts to 2 types of gammaherpesviruses, Equid herpesvirus 2 and 5 (EHV-2 and EHV-5, respectively). Both EHV-2 and EHV-5 are common in horses in Iceland. An Icelandic EHV-5 isolate was recovered by sequential culture in primary fetal horse kidney and rabbit kidney cells. Glycoprotein B, glycoprotein H, and DNA terminase genes of the isolate were fully sequenced, and the DNA polymerase gene was partly sequenced. To date, the glycoprotein B gene of EHV-5 was the only gene that has been reported to be completely sequenced in addition to small parts of the glycoprotein H, DNA polymerase, and DNA terminase genes. The present report, therefore, is a significant addition to previously reported EHV-5 sequences.Key words: Equid herpesvirus 5; gammaherpesviruses; horses; sequencing; virus isolation.Five herpesviruses are known to infect horses; 2 of them, Equid herpesvirus 2 (EHV-2) and Equid herpesvirus 5 (EHV-5), are closely related 1,7,27 (order Herpesvirales, family Herpesviridae, subfamily Gammaherpesvirinae, genus Percavirus). Foals become infected with EHV-2 and EHV-5 at 1-6 months of age, probably via the upper respiratory tract. 3,15,21 After the primary infection, the virus establishes a latent infection, most likely in the case of EHV-2 in B lymphocytes. 10 Equid herpesvirus 2 has been associated with keratoconjunctivitis, respiratory disease, pneumonia, pharyngitis, fever, enlarged lymph nodes, and lack of appetite. 2,6,8,11,18,20,25 Equid herpesvirus 5 was recently associated with multinodular pulmonary fibrosis. 29 Equid herpesvirus 2 has been detected in the majority of horses worldwide, and EHV-5 is also widespread but less common. 5,9,22,24 The 2 viruses have a strong serologic cross reactivity 1,23 and may coexist in the same horse. 7 Less is known about EHV-5 than about EHV-2, and only a few isolates have been described. 4 The 2 viruses have been shown to be common in Iceland. 28 The current report describes the isolation of EHV-5 from peripheral blood mononuclear cells from a 9-year-old mare (isolate BB5). The peripheral blood mononuclear cells from 2 Listeria monocytogenes-infected horses 16 were cocultured with primary fetal equine kidney cells (EqFKC) as previously described. a-c,28 Two isolates, BB5 and BB11, were shown, with type-specific polymerase chain reaction (PCR), to be mixtures of EHV-2 and EHV-5.Plaque purification of EHV-5 was attempted in EqFKCs but was not successful until the BB5 and BB11 isolates were alternately passaged in EqFKCs and rabbit kidney cells (RK-13), d which have previously been used for isolation of EHV-5. 4,12 The RK-13 cells were infected with BB5 or BB11 supernatant from EqFKCs and incubated for 8 days. The supernatant from the RK-13 cells was subsequently harvested and used to infect fresh EqFKCs that were incubated until they showed almost 100% cytopathology. Fresh RK-13 cells were then infected as before with this EqFKCs supernatant and incubated for 8 days when the supernatant was harvested and plaque purification carried out in EqFKCs as pre...

Gammaherpesvirus infections in equids: a review

“…It has been postulated that these viruses are the result of a coevolution process with their hosts lasting for millions of years. 7 , 8 Infections have been reported in horses both in the absence of clinical signs and in association with a wide range of clinical settings. This makes it difficult to unequivocally define what role, if any, is played by these viruses in disease causation.…”

Equine multinodular pulmonary fibrosis: Diagnosis and treatment

“…; Thorsteinsdóttir et al . ). The glycoprotein gD had been used as an antigenic target for EHV‐1; similarly, the primary antigenic target used in identifying EHV‐5 has been the gB glycoprotein (Fortier et al .…”

“…EHV-5 is incredibly slow to grow in culture, requiring 4 passages for the cytopathic effect to be reliably observed, making infection and antiviral sensitivity testing studies particularly challenging (Fortier et al 2010;Marenzoni et al 2010). Additionally, there is increasing evidence that EHV-5 presents fairly large antigenic, and potentially genetic, diversity, possibly further complicating diagnosis (Ataseven et al 2010;Fortier et al 2010;Thorsteinsdóttir et al 2010). The glycoprotein gD had been used as an antigenic target for EHV-1; similarly, the primary antigenic target used in identifying EHV-5 has been the gB glycoprotein (Fortier et al 2010).…”

Genomic Dissection of an Icelandic Epidemic of Respiratory Disease in Horses and Associated Zoonotic Cases

“…Serological tests and PCR assays for the detection of equine herpesvirus types 1, 2, 4, and 5 equine infectious anemia virus, equine arteritis virus, equine rhinitis virus A and B, equine influenza virus A type 1 (H7N7) and type 2 (H3N8), equine salemvirus, human and equine adenovirus, mammalian reovirus serotypes 1, 2, and 3, carnivore parvovirus, human rhinovirus, human enterovirus, canine pneumovirus, influenza virus A and B, parainfluenza virus 3, and mammalian coronaviruses were used according to the methods in the Manual of Diagnostic Tests and Vaccines for Terrestrial Animals produced by the OIE and other published methods ( 3 , 25 – 40 ).…”