Some Aspects of the Humoral Immune Response in IBR Vaccinated Cows

Abstract

Infectious bovine rhinotracheitis (IBR) is an acute respiratory disease with major economic consequences in cattle, caused by bovine herpesvirus type 1 (BoHV-1). Despite complex control and eradication strategies, the BoHV-1 infection continues to persist mainly due to the latently infected animals and also to its high contagiousity. Also, the efficacy of vaccines in prevention of infection has been questioned by some authors. The present study carried out on 941 bovine divided on three experimental groups (I: 0-8 months female calves, II: 8-18 months male calves and III: adult cattle), was intended to evaluate some aspects regarding the specific and non- specific humoral immune status in young and adult bovine IBR vaccinated with a live attenuated marker vaccine. In order to detect the presence of specific antibodies, a blocking enzyme-linked immunosorbent assay (ELISA) HerdCheck - IDDEX was performed on 941 serum samples (95, 72% of the farm population) collected from Limousine bovines with age ranged from 2 weeks to 7 years old. This method allows the detection and differentiation of infected cattle (positive results) from vaccinated cattle with a gE - negative vaccine (marker vaccine) (negative results). To monitor two nonspecific immune parameters: total immunoglobulins level and circulating immune complexes (CIC), bovine serum samples were submitted to the following nephelometric tests: zinc sulphate turbidity assay for the total protein concentration (Haskova modified method) and the 4,2% polyethylene glycol (PEG) precipitation technique in order to estimate the level of CIC.