The role of goats as reservoir hosts for bovine herpes virus 1 under field conditions

Sero-survey of bovine herpes virus-1 in dromedary camels and associated risk factors

Infectious bovine rhinotracheitis (IBR) is a major animal health hazard in many countries throughout the world, caused by bovine herpesvirus-1 (BoHV-1). The study’s goal was to evaluate the prevalence of BoHV-1 seropositivity among dromedary camels in three governorates in northern Egypt, as well as to identify risk variables related with BoHV-1 seropositivity. A total of 321 blood samples were collected randomly from dromedary camels living in the selected governorates and examined for presence of BoHV-1 antibody using ELISA test. The overall seroprevalence of BoHV-1 among examined camels was 5.92% (95%CI: 3.82–9.06). Univariable analysis confirmed that the significant association (P < 0.05) between sex, history of abortion, contact with small ruminants and herd size and BoHV-1 seropositivity. Using multiple logistic regression analysis, the following risk factors were identified to be related with the presence of BoHV-1 infection: sex (OR = 2.54, 95%CI: 0.63–10.22), history of abortion (OR = 4.16, 95%CI: 1.30–13.27), contact with small ruminants (OR = 5.61, 95%CI: 1.67–18.80) and large herd size (OR = 10.52, 95%CI: 2.46–44.91). This study estimated the disease’s seroprevalence in Egyptian dromedary camels, implying that camels could act as a BoHV-1 reservoir for transmission to other species.

Molecular evidence for concurrent infection of goats by orf virus and bovine herpesvirus 1

Orf is a disease of small ruminant animals, including goats and sheep, that is caused by a parapoxvirus. Although the mortality rate is low, economic losses may occur due to the clinical signs. Bovine herpesvirus 1 (BoHV-1) infection is known to cause respiratory and reproductive disorders mainly in cattle; however, it has been found to circulate among goats and sheep as well. In contrast to orf virus (ORFV), BoHV-1 does not induce clinical disease in goats. In this study, we aimed to detect the presence of ORFV by molecular methods and to uncover eventual simultaneous herpesvirus infections masked by orf disease signs. To this end, 82 goats, housed near to a cattle herd, were tested. By polymerase chain reaction (PCR), three goats (3.7%) were found to harbour both viruses, while an additional goat was positive for ORFV only. The PCR products were sequenced and phylogenetic analyses were performed. This study revealed that ORFV and BoHV-1 may be present simultaneously in an animal causing a concurrent infection. These data should be taken into consideration when looking for secondary pathogens in diseased goats, and the prevention methods should be developed accordingly.

BVDV, BHV-1 and BLV antibodies in dromedary camels of Turkey kept without and with ruminants

Camels are the only animals bred to sustain the tradition of wrestling in Turkey and are reared within a limited set of geographic areas. Farmers of such animals may also be engaged in ruminant breeding. The current research was aimed at documenting bovine viral diarrhoea virus (BVDV), bovine herpesvirus-1 (BHV-1), and bovine leukaemia virus (BLV) infections in sera collected from dromedary camels in four different geographical regions of Turkey during the years 2019-2021. All samples were tested for BVDV, BHV-1 and BLV antibodies as well as BVDV antigen by ELISA. Antibodies against BVDV were found in 16.8% of the camel sera tested. However, none of the camels sampled were positive in terms of BHV-1 and BLV antibodies as well as BVDV antigen. The prevalence was observed higher in the herds in which ruminants were raised in addition to camels (OR = 4.583, 95% CI, 1.298-16.182), (p = 0.018), while the prevalence was observed lower in the herds in which only camels were raised. This study showed that BVDV infection was more prevalent than BHV-1 and BLV infections in Turkish dromedary camels. Herewith, the camels, being a susceptible species to numerous viral ruminant diseases, may also serve as an important source of BVDV infection for other ruminant animals in the same flock.

Risk assessment and seroprevalence of bovine herpesvirus type 1 infection in dairy herds in the inner Aegean Region of Turkey

This cross-sectional study was performed to investigate the seroprevalence and associated risk factors of bovine herpesvirus type 1 (BoHV-1) infection in dairy cattle herds in Afyonkarahisar province in the Aegean Region of Turkey. Blood samples were collected from 602 cattle from 56 unvaccinated dairy herds between May 2018 and June 2019. Animal and herd-level epidemiological information was collected with a questionnaire during blood collection. Specific antibodies against BoHV-1 and bovine viral diarrhea virus (BVDV) were detected by using a virus neutralization test and a commercial indirect ELISA kit, respectively. Univariable and multivariable logistic regression analyses were used to determine any association between categorical variables and BoHV-1 seropositivity. The animal-level and herd-level seroprevalences of BoHV-1 infection were determined to be 39.53% (95% confidence interval, CI: 35.71-43.50) and 73.21% (95% CI: 60.41-83.04), respectively. Within-herd prevalence was more than 50% in 34.14% of infected herds. Cattle age (odds ratio, OR= 2.34, 95% CI: 1.58-3.44), BVDV infection (OR= 7.74, 95% CI: 5.08-11.76), and the presence of goats in the herd (OR= 2.84, 95% CI: 1.91-4.19) were identified as risk factors for BoHV-1 seropositivity by the multivariable logistic regression model. This is the first study conducted in Turkey using two-layer sampling and logistic regression analyses to determine the herd-level and animal-level seroprevalence and associated risk factors of BoHV-1 infection.

First serological evidence of BHV-1 virus in Algerian dromedary camels: Seroprevalence and associated risk factors

Infectious bovine rhinotracheitis (IBR), caused by bovine herpesvirus-1 (BHV-1), is a major livestock health concern in many countries of the world. The objectives of this cross-sectional study were (i) to estimate the seroprevalence of BHV-1 infection and (ii) to assess risk factors associated with this disease in dromedary camels in four districts of Algeria. Blood samples were taken from 865 camels from 84 randomly selected herds, and serum was analyzed for presence of antibodies against BHV-1 by indirect enzyme linked immunosorbent assay (ELISA). Logistic regression was used to determine associations between seroprevalence and potential risk factors (collected using a questionnaire). Antibodies against BHV-1 were detected in 3.7 % (32/865) of samples. Eighteen of 84 camel herds had at least one BHV-1 seropositive camel, giving a herd seroprevalence of 21.4 %. Based on univariate analysis, the introduction of purchased animals and contact with others animal herds appeared as major risk factors. By using multivariate analysis, the only important risk factor was introduction of new animals. This study provided, for the first time, evidence of BHV-1 infection in dromedary camels in Algeria; it also provided estimates of seroprevalence of this disease and suggests that camels may serve as a reservoir of BHV-1 for spread to other species.

The role of sheep in the epidemiology of Bovine alphaherpesvirus 1 (BoHV-1)

Bovine alphaherpesvirus 1 (BoHV-1) as a cusative agent for some diseases in cattle infects sheep and goat; and it is believed that these animals may be reservoir host for this virus. Thus, BoHV-1 infection in sheep and goat should be considerd when there is a program for control and eradication of this virus in cattle. Therefore, the aim of this study was to determine the seroprevalence of BoHV-1 in sheep, relationship between host and environmental factors with infection, and the role of sheep in the epidemiology of the BoHV-1. Blood samples were randomly collected from 310 healthy sheep in 6 cities of Khuzestan province (Southwest of Iran) including Ahvaz, Hendijan, Shushtar, Dezful, Masjed Soleyman and Behbahan. Sera were analyzed by virus neutralisation (VN) test for detection antibodies to BoHV-1. According to VN test, apparent and true seroprevalence seroprevalence of BoHV-1 infection was 28.4 % (95%CI: 23.4-33.4%) and 28.4 % (95%CI: 23.3-33.4%), respectively. Logistic regression revealed that the odds of infection between the age was 1.06 (95%CI: 0.9-1.25) (P > 0.05), implying that the odds of infection increased 6 % with rising one year of age. Besides, the relative frequency of infection in males was more than females', and the odds of infection in male sheep was identified to be 1.13 (95%CI: 0.47-2.71) (P > 0.05), compared to that in females. Moreover, in comparison to sheep with no history of abortion, the odds of infection in sheep with a history of abortion was 1.28 (95%CI: 0.57-2.87) (P > 0.05). The seroprevalence in Shushtar, Masjed Soleyman, Dezful, Ahvaz, Hendijan, and Behbahan were found to be 48.3, 46.7, 31.7, 20, 16.7, and 12 percent, respectively and 13.1 of fluctuation in infection can be justified by different geographical locations investigated in this study (P < 0.001). Considering the significant seroprevalence of BoHV-1, present study confirmed the role of sheep in the epidemiology of this virus and control of BoHV-1 in sheep should be considered by animal health authorities in areas where BoHV-1 is prevalent.

Antigenic relationships between Caprine alphaherpesvirus 1 (CpHV-1) and Bovine alphaherpesvirus 1 (BoHV-1) and experimental CpHV-1 infection of kids and calves

Caprine alphaherpesvirus 1 (CpHV-1) is a worldwide pathogen of goats and is closely related to Bovine alphaherpevirus 1 (BoHV-1). We herein studied the antigenic relationships of CpHV-1 with BoHV-1 and investigated the pathogenesis of CpHV-1 in kids and calves. Monoclonal antibody reactivity revealed that CpHV-1 and BoHV-1 share immunogenic epitopes in the major envelope glycoproteins gB, gC and gD. The antigenic relationship was further demonstrated by virus-neutralizing assays, in which CpHV-1 and BoHV-1 antisera presented varied degrees of cross-neutralization against the respective heterologous viruses. Although cross-neutralization was observed between both viruses and the heterologous antisera, BoHV-1 antisera neutralized CpHV-1 with higher efficiency than CpHV-1 antisera neutralized BoHV-1. Hence, the antigenic cross-reactivity between CpHV-1 and BoHV-1 should be considered upon serologic testing of goats and cattle in regions where the two viruses co-circulate. Intranasal (IN) inoculation of CpHV-1 (WI13-46 isolate) in seven seronegative kids resulted in efficient viral replication in the respiratory tract. Additionally, mild to moderate systemic and respiratory signs were observed, including apathy, hyperthermia, nasal discharge and respiratory distress. Dexamethasone administration to the inoculated kids between days 36 and 40 pi did not result in virus shedding in nasal secretions. However, latent infection had been established, as evidenced by the detection of CpHV-1 DNA in trigeminal ganglia and olfactory bulbs of kids euthanized at day 67 pi. Contrasting with the outcome of infection in kids, IN inoculation of CpHV-1 in calves did not result in productive infection as no virus replication or shedding were detected, and the animals did not develop clinical signs nor seroconverted. The animal experiments demonstrated that CpHV-1 was able to produce respiratory disease in kids, but did not replicate to detectable levels in calves.