Bovine alphaherpesvirus 1 (BoHV-1) causes a variety of clinical signs, including a respiratory disease called infectious bovine rhinotracheitis (IBR) [1]. A serological cross-reactivity has been observed between BoHV-1 and other herpesviruses [2]. This phenomenon could lead to severe consequences in BoHV-1 serology, resulting in an incorrect diagnosis of BoHV-1, both in areas where there are active control/eradication plans for IBR and in performance test stations. This study aimed to evaluate the occurrence of serological cross-reactivity between BoHV-1 and Bovine gammaherpesvirus 4 (BoHV-4). Five calves, devoid of BoHV-1 and BoHV-4 neutralizing antibodies (NAs), were selected for this study. According to the European legislation on the protection of animals used for scientific purposes, four calves were subjected to challenge infection with BoHV-4 85/16 TV strain, and a calf served as control. Serum samples were collected on 0, 14 and 21 post-challenge days (PCDs) and tested for BoHV-1 and BoHV-4 antibodies, using, via manufacturer’s instruction, the: competitive IBR gE-ELISA (A); competitive IBR gB-ELISA (B); and three indirect BoHV-4 ELISA tests (C, D, E). Virus neutralization (VN) tests were performed according to the protocols previously published [3-4] and were used in parallel to examine the collected sera. No seropositivity for BoHV-1 in any ELISA and VN tests was observed during the experiments. In all calves, antibodies for BoHV-4 were not detected on PCDs 0 by ELISA and VN tests. Otherwise, BoHV-4 ELISA tests (C, D, E) showed discordant results. In particular, on PCDs 14 and 21, by ELISA tests (C, E), only 1 out of 4 samples was detected as positive to BoHV-4. Differently, on PCD 14, the ELISA test (D) discovered 2 out of 4 samples as positive and on PCD 21, 4 out of 4 samples. In VN, the mean titer of the BoHV-4 recovered from all infected animals, already on PCD 14 was 1:8, to stay like this on PCD 21. To conclude, no serological cross-reactivity between BoHV-4 and BoHV-1 with different commercial IBR ELISA tests and BoHV-1 VN was highlighted. Moreover, indirect BoHV-4 ELISA tested have shown different diagnostic sensitivity. This research was funded by the Italian Ministry for Health (Ricerca Corrente IZSUM 10/2021).
STUDY OF CROSS-REACTIVITY ANTIBODY RESPONSE BETWEEN BOVINE GAMMAHERPESVIRUS 4 AND BOVINE ALPHAHERPESVIRUS 1: PRELIMINARY RESULTS
Marenzoni M. L.;
2023
Abstract
Bovine alphaherpesvirus 1 (BoHV-1) causes a variety of clinical signs, including a respiratory disease called infectious bovine rhinotracheitis (IBR) [1]. A serological cross-reactivity has been observed between BoHV-1 and other herpesviruses [2]. This phenomenon could lead to severe consequences in BoHV-1 serology, resulting in an incorrect diagnosis of BoHV-1, both in areas where there are active control/eradication plans for IBR and in performance test stations. This study aimed to evaluate the occurrence of serological cross-reactivity between BoHV-1 and Bovine gammaherpesvirus 4 (BoHV-4). Five calves, devoid of BoHV-1 and BoHV-4 neutralizing antibodies (NAs), were selected for this study. According to the European legislation on the protection of animals used for scientific purposes, four calves were subjected to challenge infection with BoHV-4 85/16 TV strain, and a calf served as control. Serum samples were collected on 0, 14 and 21 post-challenge days (PCDs) and tested for BoHV-1 and BoHV-4 antibodies, using, via manufacturer’s instruction, the: competitive IBR gE-ELISA (A); competitive IBR gB-ELISA (B); and three indirect BoHV-4 ELISA tests (C, D, E). Virus neutralization (VN) tests were performed according to the protocols previously published [3-4] and were used in parallel to examine the collected sera. No seropositivity for BoHV-1 in any ELISA and VN tests was observed during the experiments. In all calves, antibodies for BoHV-4 were not detected on PCDs 0 by ELISA and VN tests. Otherwise, BoHV-4 ELISA tests (C, D, E) showed discordant results. In particular, on PCDs 14 and 21, by ELISA tests (C, E), only 1 out of 4 samples was detected as positive to BoHV-4. Differently, on PCD 14, the ELISA test (D) discovered 2 out of 4 samples as positive and on PCD 21, 4 out of 4 samples. In VN, the mean titer of the BoHV-4 recovered from all infected animals, already on PCD 14 was 1:8, to stay like this on PCD 21. To conclude, no serological cross-reactivity between BoHV-4 and BoHV-1 with different commercial IBR ELISA tests and BoHV-1 VN was highlighted. Moreover, indirect BoHV-4 ELISA tested have shown different diagnostic sensitivity. This research was funded by the Italian Ministry for Health (Ricerca Corrente IZSUM 10/2021).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
