Evaluation of a commercial gE blocking ELISA test for detection of antibodies to infectious bovine rhinotracheitis virus

Abstract

Veterinarv Record (1996) 138, 520 INACTIVATED and attenuated gE deleted bovine herpesvirus type 1 (Hv-1) marker vaccines are now available in most European countries (Kaashoek and others 1994, 1995). These vaccines are suitable for reducing BHV-1 transmission and could be used in control or eradication programmes in infected countries. A commercial anti-BHV-1 gE blocking ELISA test kit is used to differentiate between immunised and naturally infected BHV-1 cattle. This study was undertaken to evaluate the sensitivity of this ELISA kit.The three European Union (EU) standard reference sera (Perrin and others 1994) InR-EUX (strong positive), tnR-EU2 (weak positive) and IBR-EU3 (negative) and serum number 45 (weak positive) were tested in dilution by two techniques: the 24 h virus neutralisation test (VNT) as previously described (Perrin and others 1994) and the commercially available gE ELISA test from Idexx (bovine rhinotracheitis virus gE antibody test kit).The optical density values obtained for the two positive standard reference sera and serum number 45 using the ELISA test were close to cutoff and could either give doubtful or weakly positive results whereas they were always positive with the 24 h VNT (Table 1).Two hundred and eighteen herds from the Auvergne area in France were randomly selected and 5194 cattle were tested by serology for BHV-1 antibodies with the 24 h VNT. Of these, 524 sera from 84 herds were positive. The 140 positive sera from the 46 herds with less than 40 per cent of infected animals were selected and 126 of these sera were tested with the commercial gE ELISA kit.The results of the 126 VNT positive sera tested with the gE ELISA kit are given in Fig 1. Most of the VNT positive sera with titres lower than 32 were negative for gE antibodies. In this study the relative sensitivity of the gE ELISA kit was 74 per cent, a result which is not in agreement with the 100 per cent sensitivity found with the same commercial kit by Lawrence and Liauw (1995). The relative sensitivities of the two VNT and the choice of positive sera may explain this difference. The sera for this study were collected in 1993 from cattle which had not been vaccinated with any gE marker vaccine or with any conventional vaccine in most cases and are representative of the positive sera found in France where most of the infected herds have a prevalence rate of less than 10 TABLE 1: gE blocking ELISA and 24h virus neutralisation test (VNT) results for the EU standard reference sera and serum number 45 gE ELISA Sera (2 tests) VNT (titre) IBR-EU1 Doubtful Positive (16) Positive IBR-EU2 Doubtful Positive (2) Positive IBR-EU3 Negative Negative Negative Number 45 Negative Positive (2) Negative 60 LL Negative so G-E Inconclusive * Positive 40 c = 30 20 10 L I _ o 2 4 8 16 32 VN Titre FIG: 1 gE blocking ELISA results for the 126 virus neutralisation test positive sera per cent infected animals with numerous weakly positive sera.Future control programmes will be based on the vaccination of cattle in infected herds with a gE nega...

Bovine herpesvirus 1 infection and infectious bovine rhinotracheitis

“…Indeed the strength of the tool is fully dependent on the capacity of the diagnostic test at detecting BoHV-1 gE specific antibody. But the sensitivity of the only available gE specific ELISA is around 70% [97,160]. This rather low level of sensitivity is responsible for 30% false negative answers at individual tests but it remains sufficient to guarantee a high sensitivity at the level of infected herds.…”

Bovine herpesvirus 1 (BHV1) seroprevalence in the breeding cattle population of the veneto region: prospects for the implementation of a control programme

“…Enhanced culling of seropositive animals and purchase restrictions are more appropriate measures in order to rapidly achieve the seronegativity of the entire stock. Moreover, the lower sensitivity of gE.ELISA in comparison with other ELISAs and the 24 h virus neutralization test (Perrin et al, 1996;De Wit et al, 1998;Hage et al, 1998;Wellenberg et al, 1998) should be mentioned; fully seronegative cattle therefore offer a greater guarantee of freedom from disease than those immunized with gE-deleted vaccine.…”

Detection of Bovine Herpesvirus 1 Glycoprotein E Antibodies in Individual Milk Samples by Enzyme-Linked Immunosorbent Assays

“…This study indicates that serum samples with low VNT titers (Յ8) could be negative in both gE ELISA systems. Perrin et al (17) also showed that serum samples with low VNT titers can give negative results in the gE-blocking ELISA. The results of the detection limit for serum (Table 2) underline these published data and indicate that in both gE ELISA systems the titers in serum are lower than the VNT titers in serum.…”