What is the role of positive and negative serum samples in the diagnosis of infectious bovine rhinotracheitis?

Answer from top 10 papers

The diagnosis of infectious bovine rhinotracheitis (IBR) involves the detection of antibodies against Bovine herpesvirus type-1 (BHV-1) in serum samples. Positive serum samples indicate the presence of antibodies and, hence, exposure to the virus, while negative serum samples lack these antibodies, suggesting no exposure. In Chandranaik et al. (2016), a micro-serum neutralization test was used to screen serum samples from various bovine species across India, with 39.2% testing positive for BHV-1 antibodies. Bettini et al. (2023) reported a 32.25% seroprevalence using serum neutralization tests, with a 4% positivity rate in semen samples for the virus. Nettleton and Russell (2017) utilized indirect enzyme-linked immunosorbent assay (ELISA) to determine a seroprevalence of 26.3% in their study population.
Interestingly, despite the detection of positive serum samples, the autonomous province of Bolzano in Italy has been declared IBR-free, as positive results were not confirmed through seroneutralization (Viu et al., 2015). This highlights the importance of confirmatory testing to validate initial screening results. Additionally, Kollannur et al. (2014) developed an indirect ELISA based on BoHV1 glycoprotein E, which showed high sensitivity and specificity, indicating its potential as a confirmatory diagnostic tool.
In summary, positive and negative serum samples are crucial for the diagnosis of IBR, with various studies reporting different seroprevalence rates (Bettini et al., 2023; Chandranaik et al., 2016; Nettleton & Russell, 2017). Confirmatory tests are essential to ensure the accuracy of the diagnosis, as evidenced by the case of Bolzano and the development of a highly sensitive and specific ELISA (Kollannur et al., 2014; Viu et al., 2015). These diagnostic tools are vital for the surveillance and control of IBR in cattle populations.

Source Papers

Infectious Bovine Rhinotracheitis Post-Eradication Program in the Autonomous Province of Bolzano, Italy: A Retrospective Study on Potential Bovine Herpesvirus Type 2 Cross-Reactivity.

Bovine alphaherpesviruses, BoAHV, can cause respiratory, genital and neurological disorders. In particular, bovine alphaherpesvirus type 1 (BoAHV1) is one of the most significant ruminant pathogens worldwide and it can heavily damage the livestock industry. BoAHV1 can cause infectious bovine rhinotracheitis (IBR) along with fertility disorders. Bovine alphaherpesvirus type 2 (BoAHV2) can cause two different conditions as well: pseudo-lumpy skin disease (PSLD) and bovine herpetic mammillitis (BHM). The autonomous province of Bolzano (Italy) has adopted several strategies to control and eradicate IBR, and it was declared in 2000 to be IBR-free by the European Commission. Since 2001, a post-eradication monitoring program has overseen the serological analysis of bulk milk and, in the presence of a positive result, a follow-up examination is performed on the individual blood serum of all bovines older than 24 months that belong to bulk milk-positive herds. Despite the detection of positives in both bulk milk and serum samples, South Tyrol has been declared IBR-free, as these positives have never been confirmed through seroneutralization. Between 2014 and 2022, approximately 41,000 bulk milk (averaging 4300 samples/year) and 3229 serum samples were tested for BoAHV1. The aim of this study was to evaluate the post-eradication program for IBR with a particular focus on the potential cross-reactivity with BoAHV2; for this reason, serum samples were also tested for BoAHV2 antibodies. This study could be of great importance for those countries that submit herds to an IBR monitoring and eradication program; performing further analyses to confirm and explain false positive outcomes would increase the reliability of the obtained results.

Open Access
Comparison of Diagnostic Tests for Diagnosis of Infectious Bovine Rhinotracheitis in Natural Cases of Bovine Abortion

Rapid and precise diagnosis plays a pivotal role in implementing suitable control measures in natural field cases of bovine abortion due to infection with bovine herpesvirus (BHV)-1. In the present study, serology, virus isolation, histopathology, immunohistochemistry (IHC) and real-time polymerase chain reaction (PCR) for amplification of the gene encoding glycoprotein B were applied for diagnosis of infectious bovine rhinotracheitis (IBR) in cases of abortion. The seroprevalence of IBR in the population studied was 26.3% as determined by indirect enzyme-linked immunosorbent assay. BHV-1 abortions occurred between 4 and 8 months of gestation with an average gestational age of 6 months. Affected placentae showed necrosis of chorionic villi and of the endothelium of small villous blood vessels with characteristic intranuclear (IN) acidophilic inclusion bodies. Similar inclusions were also seen in most of the tissues examined. BHV-1 antigen was identified immunohistochemically in necrotic foci in the liver, the endothelium of placental blood vessels, the bronchial epithelium and hepatocytes. Lesions in the brain also had IN inclusion bodies that labelled positively by IHC. Eighteen samples (nine of stomach content, two of placental cotyledons, five of pooled fetal tissue and two of vaginal discharge) out of 84 tested were positive by real-time PCR for BHV-1.

Development and validation of an indirect ELISA as a confirmatory test for surveillance of infectious bovine rhinotracheitis in vaccinated herds.

BackgroundBovine herpesvirus 1 (BoHV1) is a member of the viral subfamily of Alphaherpesvirinae that infects various species, including cattle, sheep, and goats. The virus causes infectious bovine rhinotracheitis (IBR), which is included in a European list of diseases that may require control and eradication programs. The lack of confirmatory tests affects the validity of diagnostic tools, especially those used for vaccinated herds. In this study, we report the development and validation of an indirect enzyme-linked immunosorbent assay (ELISA) based on BoHV1 glycoprotein E, which was expressed as a secreted recombinant antigen in a mammalian cell system. The performance of the new rec-gE ELISA was compared with that of commercially available indirect and/or blocking ELISAs.ResultsThe sample set included blood sera from animals from IBR-positive farms, IBR-free farms, and marker-vaccinated farms. The indirect ELISA proposed in this study is based on antibody reactivity against BoHV1 gE, and showed high sensitivity and specificity (98.41 and 99.76 %, respectively).ConclusionsThe ELISA performed well, in terms of both its diagnostic sensitivity and specificity, and as a confirmatory methodology, and therefore should improve the diagnostic protocols used for IBR surveillance.

Open Access