Molecular and antigenic characterization of bovine herpesvirus type 1 (BoHV-1) strains from cattle with diverse clinical cases in Turkey

Enhanced immunogenicity of a BoHV-1 gG-/tk- vaccine

Bovine herpesvirus type 1 (BoHV-1) is a widespread respiratory infection that significantly impacts cattle health worldwide. To address this issue in China, we previously developed a novel double gene-deleted vaccine targeting gG and tk. In this study, we further evaluated the efficacy of this vaccine by challenging vaccinated cattle with a prevalent wild-type BoHV-1 strain and comparing its effectiveness against a commercially available inactivated BoHV-1 vaccine. Post-immunization, all cattle maintained normal rectal temperatures and exhibited no respiratory symptoms. Cattle receiving the gene-deleted vaccine showed a significant increase in the expression of immune markers IFN-γ and TNF-α. Following exposure to wild-type BoHV-1, all immunized groups produced high levels of neutralizing antibodies and specific gB antibodies. Notably, virus shedding was significantly lower in the vaccinated groups compared to the non-immune challenge group. Histological analysis of lung tissues revealed that vaccinated calves had more intact lung structure than their unimmunized counterparts after the challenge. Additionally, the gG-/tk- gene-deleted vaccine demonstrated a higher protective rate based on the average scores of clinical symptoms and lung lesions. Overall, the BoHV-1 gG-/tk- gene-deleted vaccine outperformed the other vaccines tested. This study confirms that the gene-deleted vaccine provides robust protection and superior immunogenicity compared to existing inactivated vaccines, underscoring its potential for future market application.

Infectious bovine rhinotracheitis: Unveiling the hidden threat to livestock productivity and global trade

An infectious disease called infectious bovine rhinotracheitis (IBR) can lead to a number of disorders affecting cattle's respiratory system. The disease is caused by bovine alphaherpesvirus type 1 (BoAHV-1). Based on antigenic and genetic characteristics, BoAHV-1 strains are divided into subtypes 1.1, 1.2a, 1.2b, and 1.3. IBR is currently widespread throughout the world, with the exception of a few nations that have achieved eradication. The most significant characteristic of this illness is that, after a clinical or subclinical infection, the virus typically establishes a latent condition that can later be reactivated in the presence of stress, immunosuppressive conditions/substances, or other diseases. Primarily, the virus spreads by direct or indirect contact between animals. It may also be transmitted via the reproductive system, causing infectious balanoposthitis or vulvovaginitis. Most virus subtypes are associated with reproductive failure, such as fetal or embryonic resorption and abortions. The virus may also be transmitted through semen, which could lead to genital transfer. Bovine herpesvirus type 1 (BoHV-1) infection produces a variety of lesions. Lesion in the mucosal surface usually consists of white necrotic material. Regular methods for diagnosing BoHV-1 infections include isolation in cell culture, enzyme linked immunosorbent assay, virus neutralisation test, and methods based on identification of nucleic acids, like PCR. The interplay of several host, pathogen, environmental, and management factors affects the spread of IBR. Through its impacts on health and fitness, IBR can lead to production losses. In order to minimize the severity of clinical signs and stop the infection from spreading, the veterinarian may advise that sick or at-risk animals be placed under immediate isolation and vaccinated (such as intranasal vaccination, including the use of both killed and live attenuated virus vaccines) as soon as an IBR diagnosis is obtained.

Isolation of the Initial Bovine Alphaherpesvirus 1 Isolate from Yanbian, China

Bovine infectious rhinotracheitis (IBR), caused by bovine alphaherpesvirus 1 (BoAHV1), poses significant challenges to the global cattle industry due to its high contagiousness and economic impact. In our study, we successfully isolated a BoAHV1 strain from suspected infected bovine nasal mucus samples in Yanji city, revealing genetic similarities with strains from Sichuan, Egypt, and the USA, while strains from Xinjiang, Beijing, Hebei, and Inner Mongolia showed more distant associations, indicating potential cross-border transmission. Additionally, our investigation of BoAHV1 infection dynamics within host cells revealed early upregulation of gB, which is critical for sustained infection, while the expression of gC and gD showed variations compared to previous studies. These findings enhance our understanding of BoAHV1 diversity and infection kinetics, underscoring the importance of international collaboration for effective surveillance and control strategies. Furthermore, they lay the groundwork for the development of targeted therapeutics and vaccines to mitigate the impact of IBR on the cattle industry.

Genomic Characterization of a Wild-Type Bovine alphaherpesvirus 1 (BoAHV-1) Strain Isolated in an Outbreak in Central Italy

Bovine alphaherpesvirus-1 (BoAHV-1) infection is common in cattle worldwide. However, information on the spread of BoAHV-1-circulating strains in Italy remains limited. In this study, we investigated an outbreak characterized by severe respiratory symptoms in a cattle herd (n = 30) located in Central Italy. BoAHV-1 was isolated from three cattle in a cell culture, which confirmed viral infection. Next, we characterized one (16453/07 TN) of the three isolates of BoAHV-1 using whole-genome sequencing. BLASTn and phylogenetic analysis revealed a nucleotide identity >99% with all BoAHV-1 strains belonging to subtype 1.1, highlighting the genetic stability of the virus. This study reports the first full genomic characterization of a BoAHV-1 isolate in Italy, enriching our understanding of the genetic characteristics of the circulating BoAHV-1 strain in Italy.

Detection of bovine viral diarrhea virus and bovine herpes virus type 1 in cattle with and without endometritis

This study aimed to investigate the potential presence of bovine herpes virus type 1 (BHV-1) and bovine viral diarrhea virus (BVDV) in cattle uteri that did not display any clinical and macroscopic signs of infection. Virus detection involved polymerase chain reaction (PCR) test, double immunohistochemistry (IHC), and double immunofluorescence (IF). One hundred cornu uterus samples were collected from cattle aged 1 year and older. The BVDV was detected by PCR or by double IHC/IF in the collected samples from slaughterhouses in Kayseri city (Central Anatolia, Türkiye) from 2021 - 2022. By contrast, BHV-1 was detected by PCR and double IHC/IF at a rate of 16.00% and 21.00%, respectively. In the IHC and IF detection, BHV-1 was detected in endometrial epithelial cells and in some mononuclear cells in the lamina propria, periglandular areas and myometrium. Although no macroscopic lesion was found in the BHV-1-positive samples (n = 21), histopathological detection showed that two had acute endometritis, eight had subacute endometritis, eight had chronic endometritis and the three others showed no signs of endometritis. This prevalence study demonstrated for the first time that even while BVDV could not be detected in the samples, BHV-1 posed a critical potential reproductive risk in pregnant animals, as it can specifically cause abortions when it resides in cattle uteri that do not show clinical or macroscopic and even microscopic signs of infection. Additionally, this study was the first to combine PCR and double IHC/IF for BHV-1 and BVDV detection in cattle uteri.

Serum and milk levels of antibodies to bovine viral diarrhoea virus, bovine herpesvirus-1 and -4, and circulation of different bovine herpesvirus-4 genotypes in dairy cattle with clinical mastitis

Introduction

Bovine viral diarrhoea virus (BVDV) and bovine herpesvirus (BoHV)-1 and -4 are important causes of respiratory diseases and reproductive disorders of dairy cattle worldwide.

Material and Methods

Investigation of BVDV and BoHV-1 and -4 antibody levels in the serum and milk of dairy cattle in a group with clinical mastitis and a healthy group was undertaken using an indirect ELISA, and identification of the BoHV-4 genotypes in clinical mastitis cases was attempted by PCR and sequencing.

Results

Antibodies specific to BVDV, BoHV-1 and BoHV-4 were detected in the serum and milk of all dairy cattle with clinical mastitis. The cut-off values for BVDV and BoHV-1 in the sera and milk were extremely high in both healthy and mastitic animals. However, BoHV-4 antibodies were detected only in the clinically mastitic cattle, and BoHV-4 levels were higher in milk than in sera among these animals. Genotypes I and II of BoHV-4 were detected in the milk samples of four seropositive cows with clinical mastitis from the same herd.

Conclusion

The results of this investigation demonstrate that clinical mastitis cases in the same herd may have aetiology in different BoHV-4 genotypes.

Immunogenicity of an inactivated vaccine for intravaginal application against bovine alphaherpesvirus type 5 (BoHV-5)

The present study was carried out to evaluate the intravaginal vaccine potential against bovine alphaherpesvirus type 5 (BoHV-5). Sixty three cows were divided into seven groups (n: 9) and inoculated intravaginally (VA) or intramuscularly (IM) with inactivated BoHV-5, associated with the recombinant B subunit of the heat-labile enterotoxin of E. coli (rLTB), 2-hydroxyethylcellulose (Drug Delivery System A - DDS-A) or Poloxamer 407 (Drug Delivery System B - DDS-B) as follows: G1 (DDS-A + BoHV-5 + rLTB), G2 (DDS-A + BoHV-5), G3 (DDS-B + BoHV-5 + rLTB), G4 (DDS-B + BoHV-5), G5 (BoHV-5 + rLTB), G6 (Negative control) e G7 (Positive control). The local and systemic humoral responses were measured by indirect ELISA (IgA and IgG) and serum neutralization tests, and the cellular response was measured by a quantitative direct ELISA (IL-2 and IFN-Gamma). The results showed the group inoculated by the IM route, G5, demonstrated the highest levels of IgG in the vaginal mucosa among the experimental groups (p < 0.05). In the groups tested with polymers (G1 and G3) in the vaginal mucosa, even higher levels of IgG were seen in comparison to the positive control (G7; p < 0.01). Higher levels of IgA were also noted in relation to the other groups (p < 0.05) on days 30, 60 and 90 post-inoculations. The groups G1 and G3 also provided higher titers of neutralizing antibodies (Log2) in relation to other treatments (p < 0.01) 90 days after inoculation. In the nasal mucosa, there was an increase in the levels of IgA and IgG with the use of vaccines from groups G1 and G3, in relation to the positive control, G7 (p < 0.05) at 60 and 90 days after the first inoculation. Moreover, neutralizing antibodies titers were detected at 60 and 90 days by serum neutralization. The inclusion of the evaluated polymers resulted in a superior response (p < 0.05) of immunoglobulins and IL-2 and IFN-Gamma in relation to the treatment using only rLTB (G5). This data demonstrates the capabilities of a vaccine with an intravaginal application in cattle to stimulate a local and systemic immune response.

Understanding the mechanisms of viral and bacterial coinfections in bovine respiratory disease: a comprehensive literature review of experimental evidence

Bovine respiratory disease (BRD) is one of the most important diseases impacting the global cattle industry, resulting in significant economic loss. Commonly referred to as shipping fever, BRD is especially concerning for young calves during transport when they are most susceptible to developing disease. Despite years of extensive study, managing BRD remains challenging as its aetiology involves complex interactions between pathogens, environmental and host factors. While at the beginning of the twentieth century, scientists believed that BRD was only caused by bacterial infections ("bovine pasteurellosis"), we now know that viruses play a key role in BRD induction. Mixtures of pathogenic bacteria and viruses are frequently isolated from respiratory secretions of animals with respiratory illness. The increased diagnostic screening data has changed our understanding of pathogens contributing to BRD development. In this review, we aim to comprehensively examine experimental evidence from all existing studies performed to understand coinfections between respiratory pathogens in cattle. Despite the fact that pneumonia has not always been successfully reproduced by in vivo calf modelling, several studies attempted to investigate the clinical significance of interactions between different pathogens. The most studied model of pneumonia induction has been reproduced by a primary viral infection followed by a secondary bacterial superinfection, with strong evidence suggesting this could potentially be one of the most common scenarios during BRD onset. Different in vitro studies indicated that viral priming may increase bacterial adherence and colonization of the respiratory tract, suggesting a possible mechanism underpinning bronchopneumonia onset in cattle. In addition, a few in vivo studies on viral coinfections and bacterial coinfections demonstrated that a primary viral infection could also increase the pathogenicity of a secondary viral infection and, similarly, dual infections with two bacterial pathogens could increase the severity of BRD lesions. Therefore, different scenarios of pathogen dynamics could be hypothesized for BRD onset which are not limited to a primary viral infection followed by a secondary bacterial superinfection.

Phylogenetic analysis and characterization of bovine herpesvirus-1 in cattle of China, 2016-2019

Bovine herpesvirus type 1 (BoHV-1) is one of the most critical pathogens in cattle and is prevalent in China. BoHV-1 is divided into two gene types, BoHV-1.1 and 1.2, which are further differentiated into two subtypes, BoHV-1.2a and 1.2b. However, the phylogenetic analysis of BoHV-1 isolates has not been reported in China. To perform a molecular epidemiological survey based on isolates from cattle in China, 102 lung tissue samples of calves under ten months of age with respiratory disease (BRD) that died from 2016 to 2019 in China were used to isolate BoHV-1 with Madin-Darby bovine kidney (MDBK) cells. Part of the BoHV-1 isolates were applied to the phylogenetic analysis based on the region of the glycoprotein C (gC) gene of BoHV-1. Thirty BoHV-1 isolates were obtained, and the gC gene of 13 isolates was amplified by polymerase chain reaction (PCR) methods and sequenced. The result of the phylogenetic analysis according to the 451-nucleotide portion of the gC gene found that all of 13 isolates belonged to the BoHV-1.2b gene subtype, but these isolates had located two different phylogenetic tree branches. The gC gene sequence homology of isolates in group1 was higher with a reference strain of BoHV-1.2b EVI14 up to 98.0-100%, while in group 2, this was higher with reference strain BoHV-1.2b B589 up to 97.8-99.8%. The deduced amino acid sequence of gC from isolates in group 2 had two amino acid mutations with interference strain BoHV-1.2b K22 or BoHV-1.1 COOPER. The cytopathic effects (CPEs) of BoHV-1 isolates in group 2 were ulcered on the centration like a volcano on MDBK cell, and different from traditional CPEs of BoHV-1. Overall, BoHV-1.2b seems to be the primary strain of BoHV-1 in cattle in China and is also a critical cause of BRD. These BoHV-1.2b isolates had significant genetic variations.