Bovine Herpesvirus Type 1 Infections Research Articles

Bovine herpes virus type-4 infection among postpartum dairy cows in California: risk factors and phylogenetic analysis

The aims of this study were to determine the prevalence and associated risk factors of bovine herpes virus type-4 (BoHV-4) infection and describe the genetic characteristics and predominant genotypes of the virus in Yolo and Tulare counties, California. A cross-sectional study involving multi-stage sampling technique was used. One hundred and forty-eight post-partum cows were enrolled from 11 dairy farms. Uterine/vaginal samples were collected and tested for BoHV-4 and other co-infecting viruses using real-time PCR. Data were analysed using multilevel logistic mixed-effect model. Phylogenetic analysis of 10 BoHV-4 isolates was conducted by targeting three open reading frames (ORF3, ORF8 and ORF 22) of the viral genome. The prevalence of BoHV-4 infection was 22.3% (33/148), while post-partum metritis was 33.8% (48/142). Strong association was found between BoHV-4 infection and lactation number, lactation stage and post-partum metritis. The odds of being positive for BoHV-4 infection were 6.47 times (95% CI 1.17-35.92; P 240 days). Cows with post-partum metritis were 4.51 times (95% CI 1.27-16.02; P < 0.05) more likely to test positive for BoHV-4 infection compared with those without post-partum metritis. Phylogenetic analysis of BoHV-4 based on sequencing of glycoprotein and thymidine kinase (TK) genes revealed genetic variability of the virus with glycoprotein B genotype 1 and TK genotype 2 as being dominant genotypes. The reported high genetic variability of BoHV-4 indicates the possibility of co-infection with multiple genotypes.

Spatial analysis for bovine viral diarrhea virus and bovine herpesvirus type 1 infections in the state of Para\xedba, northeastern Brazil

BackgroundBovine Viral Diarrhea Virus (BVDV) and Bovine Herpesvirus type 1 (BoHV-1) cause reproductive problems in cattle and restrictions on international trade in animals worldwide. Both infections were detected in cattle herds in the Paraíba state, Northeastern Brazil, however, the spatial distribution and geographic identification of positive herds for these viruses has never been examined. Therefore, the aim of this study was to describe the spatial pattern of apparent prevalence estimate and to identify spatial clustering of positive herds of BVDV and BoHV-1 infections in cattle herds from the state of Paraíba, Northeastern Brazil.ResultsThe herd-level prevalence for BVDV and BoHV-1 infections in Paraíba were, respectively, 65.5% (95% CI: 61.1–69.7) and 87.8% (95% CI: 84.5–90.5). The average apparent within-herd prevalence of BVDV was 31.8% and of BoHV-1 was 62.4%. The predicted prevalence was highest (0.42–0.75) for BVDV in the west, north and eastern part of Sertão and in the central and eastern part of Agreste/Zona da Mata. For BoHV-1, the highest predicted prevalence (0.74–0.97) was in some local areas across Sertão and throughout the eastern part of Agreste/Zona da Mata. Six significant clusters were detected for BVDV, a primary cluster covering the eastern Sertão region, with 11 herds, radius of 24.10 km and risk relative (RR) of 2.21 (P < 0.001) and five smaller significant clusters, involving one or two herds in Agreste/Zona da Mata region with a high RR. A significant clustering of BoHV-1 positive herds (P < 0.001) was detected in Agreste/Zona da Mata region with a radius of 77.17 km and a RR of 1.27, with 103 cases. Consistency was found between kriging and SatScan results for identification of risk areas for BVDV and BoHV-1 infections.ConclusionsThe clusters detected contemplated different areas of the state, with BVDV cluster located in the Sertão and BoHV-1 in Agreste/Zona da Mata stratum. Through the risk mapping, it was possible to identify the areas in which the risk is significantly elevated, coincided with areas where there are borders with other states and in which there is a high movement of animals.

Susceptibility of mice to bovine herpesvirus type 5 infection in the central nervous system.

Bovine herpesvirus type 5 (BoHV-5) is an important pathogen that causes meningoencephalitis in cattle. Few studies have used the mouse as a model for BoHV-5 infection. Despite the fact that BoHV-5 can infect mice with immune deficiencies, little is known about viral replication, immune response, and the course of infection in the central nervous system (CNS) of wild-type mice. Therefore, the aim of this study was to evaluate the response in the CNS of BALB/c mice acutely infected with BoHV-5at different days post-inoculation (dpi). BoHV-5, when inoculated intracranially, was able to infect and replicate within the CNS of BALB/c mice. Until 15 dpi, the mice were able to survive without showing prominent neurological signs. The infection was accompanied by a Th1 immune response, with a significant expression of the cytokines IFN-γ and TNF-α and chemokine CCL-2. The expression of these cytokines and chemokines was most significant in the early course of infection (3 and 4 dpi), and it was followed by meningoencephalitis with perivascular cuffing and periventriculitis, composed mainly of macrophages and lymphocytes. After the expression of cytokines and chemokine, the mice were able to curb BoHV-5 acute infection in the brain, since there was a decrease in the number of BoHV-5 DNA copies after 3 dpi and viable viral particles were not detected after 6 dpi. Importantly, BoHV-5 was able to infect the trigeminal ganglia during acute infection, since a large number of BoHV-5 DNA copies were detected on 1 and 2 dpi.

Bovine herpes virus type 4 alters TNF-α and IL-8 profiles and impairs the survival of bovine endometrial epithelial cells

Bovine herpes virus type 4 (BoHV-4) can be transmitted by contaminated semen to cows at the time of breeding and may cause uterine disease. The aim of this study was to characterize the susceptibility of bovine endometrial epithelial cells (bEEC) to BoHV-4 by using an in vitro model. When bEEC were challenged with different multiplicity of infection (MOI; from 0.001 to 10) of BoHV-4 for 6days, a significant decrease in cell survival with increasing MOI was observed. The bEEC were subsequently challenged with BoHV-4 MOI 0.1 for 7days. During the first 4days, numbers increased in a similar way in controls and infected group (p<0.01 when compared to Day 0). After Day 4, numbers of live cells in infected samples decreased when compared to controls and were lower than control at Day 7 (p<0.01). From titration and qPCR, increasing number of viral particles was observed from Day 1, and reached a plateau at Day 5. Concentrations of IL-8 increased with time and were higher in supernatants from infected cells than in controls (p<0.0001). TNF-α concentrations presented similar profile as cell survival ones. In conclusion, the survival of bEEC was strongly impaired by BoHV-4 infection in a time and dose dependent manner and supernatant cytokine profiles were altered. This information supports BoHV-4 implication in clinical cases of uterine diseases and the existence of a risk of BoHV-4 transmission from infected males through animal breeding.

Risk factors associated with BoHV-1 and BVDV seropositivity in buffaloes (Bubalus bubalis) from the State of Paraiba, Northeastern Brazil

This study aimed to identify the risk factors associated with Bovine Herpesvirus Type 1 (BoHV-1) and Bovine Viral Diarrhea Virus (BVDV) infections in buffaloes in the State of Paraiba, Northeastern Brazil, using 136 female buffaloes ? 24 months old from 14 herds. For the serological diagnosis of the BoHV-1 and BVDV infections, the virus-neutralization test (VN) was used and in each herd, an epidemiological questionnaire was applied in order to obtain data to be used in the risk factor analysis. Of the 136 animals 86 (63.2%) were positive for BoHV-1 and 12 (8.8%) for BVDV. The presence of watering points (odds ratio = 17.68; 95% CI = 3.74 – 83.04) was identified as risk factor for BoHv-1, and animal purchasing was a risk factor for both BoHV-1 (odds ratio = 68.64; 95% CI = 12.28 – 383.73) and BVDV (odds ratio = 3.64; 95% CI = 1.04 – 12.76). The results from the present study showed an evidence of the presence of BoHV-1 and BVDV infections in buffaloes from the State of Paraiba, Northeastern Brazil. It is suggested that control and prevention measures should be adopted, such as the use of diagnostic tests prior to animal purchasing and the use of vaccines to avoid the introduction of infected animals into the herds and the consequent dissemination of the infections, minimizing economic losses.

Risk factors associated with BoHV-1 and BVDV seropositivity in buffaloes (Bubalus bubalis) from the State of Paraiba, Northeastern Brazil

This study aimed to identify the risk factors associated with Bovine Herpesvirus Type 1 (BoHV-1) and Bovine Viral Diarrhea Virus (BVDV) infections in buffaloes in the State of Paraíba, Northeastern Brazil, using 136 female buffaloes ? 24 months old from 14 herds. For the serological diagnosis of the BoHV-1 and BVDV infections, the virus-neutralization test (VN) was used and in each herd, an epidemiological questionnaire was applied in order to obtain data to be used in the risk factor analysis. Of the 136 animals 86 (63.2%) were positive for BoHV-1 and 12 (8.8%) for BVDV. The presence of watering points (odds ratio = 17.68; 95% CI = 3.74 – 83.04) was identified as risk factor for BoHv-1, and animal purchasing was a risk factor for both BoHV-1 (odds ratio = 68.64; 95% CI = 12.28 – 383.73) and BVDV (odds ratio = 3.64; 95% CI = 1.04 – 12.76). The results from the present study showed an evidence of the presence of BoHV-1 and BVDV infections in buffaloes from the State of Paraíba, Northeastern Brazil. It is suggested that control and prevention measures should be adopted, such as the use of diagnostic tests prior to animal purchasing and the use of vaccines to avoid the introduction of infected animals into the herds and the consequent dissemination of the infections, minimizing economic losses.

Latency of bovine herpesvirus type 5 (BoHV-5) in tonsils and peripheral blood leukocytes

Bovine herpesvirus types 1 (BoHV-1) and 5 (BoHV-5) can both establish latency in the trigeminal ganglion. Non-neural sites of latency have been described for BoHV-1 but not for BoHV-5. The aim of this study was to determine whether peripheral blood leukocytes and tonsils are targets for BoHV-5 infection and to establish whether all stages of that virus's infectious cycle can occur in those cell types. Comparisons with BoHV-1 infection of these tissues were also made in order to better understand the pathogenesis of both viruses.BoHV-1 and BoHV-5 were isolated from tonsils of acutely-infected calves. BoHV-5 was also isolated from a tonsil homogenate after dexamethasone-induced reactivation. During latency, infectious virus was recovered from a tonsil explant of one BoHV-5-infected calf. The genomes of BoHV-5 and BoHV-1 were detected in tonsils from acutely-infected calves although were not detected in tonsils from latently-infected calves or from calves treated with dexamethasone. Virus DNA was intermittently detected in leukocytes.The study has shown that BoHV-5 can establish latency in bovine tonsils and peripheral white blood cells, and that it can be reactivated from latently-infected tonsils, which might contribute to viral transmission. The titres of BoHV-1 and BoHV-5 in tonsils were similar, suggesting that replication at this site is a common feature for both viruses.

Seroprevalence of bovine viral diarrhoea virus, bovine herpesvirus 1 and bovine leukaemia virus in Iranian cattle and associations among studied agents

Bovine viral diarrhoea virus (BVDV), bovine herpesvirus type 1 (BoHV1) and bovine leukaemia virus (BLV) are among the most important pathogens of dairy cattle which cause significant economic burden around the world. The aim of this study was to investigate seroprevalence and concurrent presence of antibodies against BVDV, BoHV1 and BLV in dairy cattle in Iran. A total of 882 animals were sampled and the presence of antibodies against BVDV, BoHV1 and BLV was determined by commercial Enzyme link immunosorbent assay (ELISA) kits. The overall BVDV, BoHV1 and BLV seroprevalence was 64.4%, 31.9% and 16.2%, respectively. The prevalence of antibodies against mentioned pathogens varied among different provinces studied. In addition, no correlation was observed between BLV seropositivity and either BVDV or BoHV1 seropositivity while there was a positive correlation between BVDV and BoHV1 seropositivity (P < 0.01). The results of the current study revealed that BVDV, BoHV1 and BLV infections are present in different regions of Iran and thus it seems necessary to implement control programmes to prevent further spread of mentioned pathogens. Moreover, it was demonstrated that a previous infection with either BVDV or BoHV1 might be a risk factor for future infection with BoHV1 or BVDV, respectively.

Evaluation of total oxidative stress and total antioxidant status in cows with natural bovine herpesvirus-1 infection

Viruses, including herpes viruses, can alter oxidative balance by either increasing the formation of free radicals or inhibiting synthesis of enzymes involved in oxidative defense within host cells. This study examined the occurrence of oxidative and antioxidative balance in cows naturally infected with bovine herpesvirus type 1 (BHV-1) under field conditions. Clinical history indicated that cows had been sick and showed mild to severe respiratory signs, characterized by dullness, coughing, and lacrimation, and a high febrile response. All samples obtained from the infected animals during clinical examination were confirmed as positive for bovine herpesvirus type 1 by PCR. Control cows showed no clinical abnormalities and PCR results were negative. Total antioxidative status, total oxidant status, oxidative stress index, and some biochemical parameters were measured. The level of total antioxidative status was significantly lower in infected animals, compared with the healthy control group (P = 0.025). However, there was no statistically significant difference between the 2 groups for total oxidant status and oxidative stress index levels. Furthermore, there was a significant decrease in the infected groups, with respect to concentrations of alkaline phosphatase, alanine transferase, γ glutamyl transferase, monocyte, and erythrocyte (P < 0.05). On the other hand, aspartate aminotransferase and creatinine kinase concentrations significantly increased in the cows infected with BHV-1. In conclusion, the data obtained hereby explained that animals with infected BHV-1 seemed to have more oxidative stress and low antioxidant defense. Moreover, future research conductance is needed on antioxidative and oxidative balance to understand pathophysiology of BHV-1 infections.

Bovine herpesvirus type 4 infection modulates autophagy in a permissive cell line

Bovine herpesvirus type 4 (BoHV-4), like other herpesviruses, induces a series of alterations in the host cell that modify the intracellular environment in favor of viral replication, survival and spread. This research examined the impact of BoHV-4 infection on autophagy in BoHV-4 infected Madin Darby bovine kidney (MDBK) cells. Protein extracts of BoHV-4 infected and control MDBK cells were subjected to Western blot. The concentrations of the autophagy and apoptosis-related proteins Beclin 1, p21, PI3 kinase, Akt1/2, mTOR, phospho mTOR, p62 and the light chain three (LC3) were normalized to the actin level and expressed as the densitometric ratio. Western blot analysis of virus-infected cells revealed that autophagic degradation pathway was induced in the late phase of BoHV-4 infection. After 48 h post-infection the protein LC3II, which is essential for autophagy was found to be markedly increased, while infection of MDBK cells with BoHV-4 resulted in a depletion of p62 levels. Becline 1, PI3 kinase, Akt1/2 and p21 expression increased between 24 and 48 h post-infection. Surprisingly, mTOR and its phosphorylated form, which are negative regulators of autophagy, also increased after 24 h post-infection. In conclusion, our findings suggest that BoHV-4 has developed mechanisms for modulation of autophagy that are probably part of a strategy designed to enhance viral replication and to evade the immune system. Additional studies on the relationship between autophagy and BoHV-4 replication and survival, in both lytic and latent replication phases, are needed to understand the role of autophagy in BoHV-4 pathogenesis.

Susceptibility of neuron-like cells derived from bovine Wharton’s jelly to bovine herpesvirus type 5 infections

BackgroundBovine herpesvirus type 5 (BoHV-5), frequently lethal in cattle, is associated with significant agricultural economic losses due to neurological disease. Cattle and rabbits are frequently used as models to study the biology and pathogenesis of BoHV-5 infection. In particular, neural invasion and proliferation are two of the factors important in BoHV-5 infection. The present study investigated the potential of bovine Wharton’s jelly mesenchymal stromal cells (bWJ-MSCs) to differentiate into a neuronal phenotype and support robust BoHV-5 replication.ResultsUpon inducing differentiation within a defined neuronal specific medium, most bWJ-MSCs acquired the distinctive neuronal morphological features and stained positively for the neuronal/glial markers MAP2 (neuronal microtubule associated protein 2), N200 (neurofilament 200), NT3 (neutrophin 3), tau and GFAP (glial fibrillary acidic protein). Expression of nestin, N200, β-tubulin III (TuJI) and GFAP was further demonstrated by reverse transcriptase polymerase chain reaction (RT-PCR). Following BoHV-5 inoculation, there were low rates of cell detachment, good cell viability at 96 h post-infection (p.i.), and small vesicles developed along neuronal branches. Levels of BoHV-5 antigens and DNA were associated with the peak in viral titres at 72 h p.i. BoHV-5 glycoprotein C mRNA expression was significantly correlated with production of progeny virus at 72 h p.i. (p < 0.05).ConclusionThe results demonstrated the ability of bWJ-MSCs to differentiate into a neuronal phenotype in vitro and support productive BoHV-5 replication. These findings constitute a remarkable contribution to the in vitro study of neurotropic viruses. This work may pave the way for bWJ-MSCs to be used as an alternative to animal models in the study of BoHV-5 biology.

Role of bovine herpesvirus type 5 (BoHV-5) in diseases of cattle. Recent findings on BoHV-5 association with genital disease

Bovine herpesvirus type 5 (BoHV-5) belongs to the family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus. This virus is a major causative agent of non-suppurative meningoencephalitis in young cattle. It was first isolated in 1962 from a neurological disease outbreak in Australia. BoHV-5 is genetically and antigenically related to bovine herpesvirus type 1 (BoHV-1), a highly prevalent virus responsible for respiratory and genital disease in cattle. Initially, BoHV-5 was considered a subtype of BoHV-1 (BoHV-1.3). However, the exclusive presentation of outbreaks of neurological disease suggested that the virus was a new agent with characteristics of neuropathogenicity. Even though both are neurotropic viruses, only BoHV-5 is capable of replicating extensively in the central nervous system and inducing neurological disease. Occasionally, encephalitis caused by BoHV-1 has been reported. Like other alpha-herpesviruses, BoHV-5 can establish latency in nervous ganglia and, by stress factors or glucocorticoid treatment, latent virus can be reactivated. During episodes of reactivation, the virus is excreted in nasal, ocular and genital secretions and transmitted to other susceptible hosts. Recently, BoHV-5 has been associated with infection of the reproductive tract. The virus has been isolated and the presence of viral DNA has been demonstrated in semen samples from Brazil and Australia and natural transmission of the virus through contaminated semen has also been described. Embryos and oocytes are permissive for BoHV-5 infection and BoHV-5 DNA has been detected in the central nervous system of aborted fetuses. The objective of this review is to compile the limited information on the recent association between BoHV-5 and reproductive disorders in cattle.

Apoptotic and developmental effects of bovine Herpesvirus type-5 infection on in vitro-produced bovine embryos

Bovine Herpesvirus type-5 (BoHV-5), which is potentially neuropathogenic, was recently described to be related with reproductive disorders in cows. The objective was to elucidate mechanisms involved in propagation of BoHV-5 in embryonic cells. For this purpose, bovine embryos produced in vitro were assayed for apoptotic markers after experimental infection of oocytes, in vitro fertilization, and development. Host DNA fragmentation was detected with a TUNEL assay, expression of annexin-V was measured with indirect immunofluorescence, and viral DNA was detected with in situ hybridization. Infective BoHV-5 virus was recovered from embryos derived from exposed oocytes after two consecutive passages on Madin-Darby bovine kidney (MDBK) cells. The viral DNA corresponding to US9 gene, localized between nucleotides 126243 to 126493, was detected in situ and amplified. There was no significant difference between the ratio of TUNEL stained nuclei and total cells in good quality blastocysts (0.87 ± 0.05, mean ± SD), but there were differences (P < 0.05) between infected (0.18 ± 0.05) and uninfected blastocysts (0.73 ± 0.07). The Annexin-V label was more intense in uninfected embryos (0.79 ± 0.04; P < 0.05). The quality of infected and uninfected embryos was considered equal, with no significant effect on embryonic development. In conclusion, we inferred that BoHV-5 infected bovine oocytes, replicated, and suppressed some apoptotic pathways, without significantly affecting embryonic development.

The possible role of bovine herpesvirus type-4 infection in cow infertility

Experimental and field studies have proven that the bovine herpesvirus type-4 (BHV-4) infection leads to various reproductive system problems. In this study, the role of BHV-4 infection in repeat breeding was investigated serologically. Eighty-four samples were obtained from repeat-breeding diagnosed cows in two organized dairy herds; an equal number of healthy cows were sampled from the same farms. The rest of the samples (105) were obtained from reproductively normal cows that were breeding in 18 small enterprises as a control group. The seropositivity proportion in repeat-breeding diagnosed cows was found to be significantly higher (69% (58/84)) than other cows (44% (37/84)) on the same farms. The lowest antibody positivity value for BHV-4 was detected as 24.7% (26/105) in the samples from family-type small farms. The odds ratio (OR) value was calculated as 2.834 in repeat-breeding diagnosed and healthy cows on the same farms, while 6.778 was determined in cows with and without reproductive problems on organized farms compared to small farms. As a result, the BHV-4 infection can be considered one of the reasons for repeat breeding besides other reproductive disorders.

Selection and characterization of brivudin resistant bovine herpesvirus type 5

Bovine herpesvirus type 5 (BoHV-5) is the agent of meningoencephalitis, an important disease of cattle in South America. The neuropathogenesis of BoHV-5 infection is poorly understood and most previous research focused on the role of envelope glicoproteins in neurovirulence. Thymidine kinase (TK) is a viral enzyme necessary for virus replication in neurons and, therefore, represents a potential target for virus attenuation. The selection and characterization of BoHV-5 variants resistant to the nucleoside analog brivudin (BVDU), which selects TK-defective viruses is here described. Several BVDU-resistant clones were obtained after multiple passages in tissue culture in the presence of BVDU and one clone (BoHV-5/R-27) was further characterized. The selected clone replicated to similar titers and produced plaques with similar size and morphology to those of wild-type virus (SV507/99). The genetic stability of the resistant virus was demonstrated after ten passages in cell culture in the absence of the drug. Moreover, the drug-resistant virus showed reduced virulence in a rabbit model: virus inoculation in four rabbits did not result in disease, in contrast with 75% morbidity (3/4) and 50% mortality (2/2) among rabbits inoculated with the parental virus. These results demonstrate that BoHV-5 is sensitive to BVDU and that drug-resistant mutants can be readily selected upon BVDU treatment. BVDU-resistant mutants, likely defective in TK, retained their ability to replicate in tissue culture yet were attenuated for rabbits. This strategy to obtain TK-defective BoHV-5 may be useful to study the role of TK in BoHV-5 neuropathogenesis and for vaccine development.

Selection and characterization of brivudin resistant bovine herpesvirus type 5

Bovine herpesvirus type 5 (BoHV-5) is the agent of meningoencephalitis, an important disease of cattle in South America. The neuropathogenesis of BoHV-5 infection is poorly understood and most previous research focused on the role of envelope glicoproteins in neurovirulence. Thymidine kinase (TK) is a viral enzyme necessary for virus replication in neurons and, therefore, represents a potential target for virus attenuation. The selection and characterization of BoHV-5 variants resistant to the nucleoside analog brivudin (BVDU), which selects TK-defective viruses is here described. Several BVDU-resistant clones were obtained after multiple passages in tissue culture in the presence of BVDU and one clone (BoHV-5/R-27) was further characterized. The selected clone replicated to similar titers and produced plaques with similar size and morphology to those of wild-type virus (SV507/99). The genetic stability of the resistant virus was demonstrated after ten passages in cell culture in the absence of the drug. Moreover, the drug-resistant virus showed reduced virulence in a rabbit model: virus inoculation in four rabbits did not result in disease, in contrast with 75% morbidity (3/4) and 50% mortality (2/2) among rabbits inoculated with the parental virus. These results demonstrate that BoHV-5 is sensitive to BVDU and that drug-resistant mutants can be readily selected upon BVDU treatment. BVDU-resistant mutants, likely defective in TK, retained their ability to replicate in tissue culture yet were attenuated for rabbits. This strategy to obtain TK-defective BoHV-5 may be useful to study the role of TK in BoHV-5 neuropathogenesis and for vaccine development.

Seroprevalence and risk factors associated with bovine herpesvirus type 1 (BHV1) infection in non-vaccinated cattle herds in Andalusia (South of Spain)

An epidemiological and serological survey of bovine herpesvirus 1 (BHV1) infection was conducted in Andalusia from January to April of 2000. A total of 4,035 blood samples were collected from 164 herds. A questionnaire, which included variables potentially associated with infection, was filled out for each herd. Serum samples were obtained to identify specific BHV1 antibodies and were tested using a blocking ELISA test. The observed crude odds ratio (OR) (estimate of the chance of a particular event occurring in an exposed group in relation to its rate of occurrence in a nonexposed group) for vaccination is 9.8 (95% confidence interval: 8.3-11.7). The vaccinated group comprised large dairy farms. This study can only be considered as representative of unvaccinated, small to medium size dairy farms and beef farms in Andalusia. True seroprevalence of the BHV1 virus in nonvaccinated bovine populations in Andalusia reached 45.7% of individuals and 70.4% of herds. Risk factors for BHV1 infection in bovine Andalusian nonvaccinated herds are nonexistence of specific cattle infrastructure (OR: 3.07), beef crossbreeding (OR: 7.90), affiliation with Livestock Health Defence Associations (OR: 2.57), a history of reproductive disorders (OR: 8.39), external replacement (OR: 2.74), proximity to an urban area (OR: 6.11) and herd size (41.98). To control for confounding effects, a binomial logistic regression model was developed. From this regression, BHV1 infections are concentrated in large herds, with external replacement, located close to urban areas. This is the first published report on BHV1 prevalence in the South of Spain.

Presence of Bovine herpesvirus type 4 (BHV-4) infection in bulls for artificial insemination in Serbia

Bovine herpesvirus type 4 (BHV-4) is a worldwide distributed gammaherpesvirus, with different antigenic and biologic properties from all the other bovine herpesviruses. In vivo distribution of BHV-4 was examined by testing various organs of experimentally infected calves. However, limited data regarding excretion and transmission of BHV-4 from naturally infected cattle are available. In this report, we describe the detection of BHV-4 in the semen of bulls used for artificial insemination. Blood and semen of bulls from two major centers for artificial insemination (A.I. center) were examined in this study. In order to detect the presence of BHV-4 infection in the studied herds, 35 serum samples from Center I and 15 from Center II were examined using indirect ELISA for detection of specific anti-BHV4 IgGl immunoglobulins. Serological examination showed that 18 out of 50 serum samples were positive for BHV-4 antibodies. Despite the fact that BHV-4 was not isolated from semen samples the, presence of BHV-4 was detected in one sample using the nested PCR. This fact can be used to presuppose that artificial insemination is a potential route for BHV-4 transmission. .

Pro and contra IBR-eradication

Bovine herpesvirus type 1 (BoHV-1) is the causative agent of respiratory and genital tract infections such as infectious rhinotracheitis (IBR), infectious pustular vulvovaginitis (IPV, balanoposthitis (IBP), and abortion. Despite of a pronounced immune response, the virus is never eliminated from an infected host but establishes life-long latency and may be reactivated at intervals. Europe has a long history of fighting against BoHV-1 infections, yet, only a small number of countries has achieved IBR-eradication. Therefore, it seemed appropriate to review the reasoning pro and contra such a task. Clearly, the goal can indeed be achieved as has been demonstrated by a number of European countries. However, detection and stamping out of seemingly healthy virus carriers is inevitable in the process. Unfortunately, the use of vaccines is only of temporary and limited value. Therefore, there are numerous considerations to be put forward against such plans, including the high costs, the great risks, and the unsatisfactory quality of tools. If either control or eradication of IBR is nonetheless a goal, then better vaccines are needed as well as better companion tests. Moreover, better tools for the characterization of viral isolates are required. Collaborative actions to gather viral strains from as many countries as possible for inclusion into a newly created clustering library would be most advantageous.

A monoclonal antibody-based ELISA allows discrimination between responses induced by bovine herpesvirus subtypes 1 (BoHV-1.1) and 2 (BoHV-1.2)

Bovine herpesvirus type 1 (BoHV-1) has distinct subtypes according to genomic characterization. Immune responses induced by BoHV-1 subtype 1 (BoHV-1.1) are not distinguishable from those induced by BoHV-1 subtype 2 (BoHV-1.2) through conventional serological methods. In the present report, an enzyme linked immunosorbent assay is described that allows discrimination between immune responses in cattle immunized with either subtype, based on a monoclonal antibody that recognizes specifically the amino-terminal region of glycoprotein C (gC) on BoHV-1.1 strains, thus not reacting with BoHV-1.2a. The test displayed a sensitivity of 92%, specificity of 90% and a good correlation with serum neutralization tests on samples from BoHV-1.1-immunized calves ( κ = 0.799). The test may be useful to provide new insights into the roles played by each of these two subtypes in the epidemiology of BoHV-1 infections.