Neurological disorder in cattle associated with bovine herpesvirus 4

E.A Costa,F.M Coelho,H.B Amorim,G.B.L Lima,A.C Vasconcelos,M.R.Q Bomfim,M Resende

doi:10.1590/s0102-09352011000400006

Abstract

A nested PCR assay was used to diagnose bovine encephalitis through herpesviruses including bovine herpesvirus 5 (BHV-5), bovine herpesvirus 1 (BHV-1), Aujeszky's disease virus (SHV-1), and ovine herpesvirus 2 (OHV-2) in 14 fragments of central nervous system (CNS) from cattle that died with neurological signs. In addition, as some samples of bovine herpesvirus type 4 (BHV-4) have been isolated from neural tissue, it was also tested by nested PCR. The cases of encephalitis occurred in isolation at different times of the year and did not present any seasonality. The duration of the clinical course ranged between 1 to 15 days, and in 64.3% of the cases it manifested between 1 to 2 days. The most frequently observed neurological signs were ataxia, recumbency, unsteadiness and inability to stand, opisthotonus, paddling movements, nystagmus and ptyalism. In the nested assay, there was no evidence of: BHV-1, SHV-1 or OHV-2 in the DNA obtained from the CNS in any of the samples. But the presence of BHV-4 was found in all fragments of the CNS in cattle which died presenting neurological signs. Moreover, BHV-5 was found in association with BHV-4 in two of these samples.

Highlights

Out of all bovine herpesviruses, the bovine herpesvirus type 4 (BHV-4) is the most intriguing because it is isolated in apparently healthy bovines as well as in a wide range of clinical conditions such as abortions, skin lesions, metritis, mastitis, ulcerative mammilitis, bladder and rumen tumors, cases of malignant catarrhal fever and ocular, respiratory, genital, enteric and neurological infections (Asano et al, 2003; Dewals et al, 2006).Neurological disorder in cattle...Due to the small number of carriers, the slow reproductive cycle with low viral titer/load and slow cytopathic effect, common properties in the cytomegaloviruses (CMV), the BHV-4 was firstly grouped in the betaherpesvirus subfamily
This paper reports the presence of the BHV-4 DNA in the central nervous system of cattle which died with neurological disorders in Minas Gerais State, Brazil
A total of 14 fragments of central nervous system (CNS) derived from cattle that died with neurological signs were sent to the Laboratory of Compared Virology for encephalic herpesvirus diagnosis

Summary

Introduction

Due to the small number of carriers, the slow reproductive cycle with low viral titer/load and slow cytopathic effect, common properties in the cytomegaloviruses (CMV), the BHV-4 was firstly grouped in the betaherpesvirus subfamily. The BHV-4 pathogenicity has not been well defined as of yet (Izumi et al, 2006). It seems that the BHV-4 infection has increased and there is a strong association between BHV-4 high antibodies loads and reproductive system infections in bovines (Goyal and Naeem, 1992). Experimental inoculations do not replicate the clinical disease, suggesting that the BHV-4 reactivation may be related to additional factors or conditions in order to become pathogenic (Goyal and Naeem, 1992)

Methods

Results

Conclusion