Evaluation of a bovine rotavirus VP6 vaccine efficacy in the calf model of infection and disease

Use of live attenuated recombinant Newcastle disease virus carrying avian paramyxovirus 2 HN and F protein genes to enhance immune responses against species A rotavirus VP6 protein

Numerous infectious diseases in cattle lead to reductions in body weight, milk production, and reproductive performance. Cattle are primarily vaccinated using inactivated vaccines due to their increased safety. However, inactivated vaccines generally result in weaker immunity compared with live attenuated vaccines, which may be insufficient in certain cases. Over the last few decades, there has been extensive research on the use of the Newcastle disease virus (NDV) as a live vaccine vector for economically significant livestock diseases. A single vaccination dose of NDV can sufficiently induce immunity; therefore, a booster vaccination dose is expected to yield limited induction of further immune response. We previously developed recombinant chimeric NDV (rNDV-2F2HN), in which its hemagglutinin-neuraminidase (HN) and fusion (F) proteins were replaced with those of avian paramyxovirus 2 (APMV-2). In vitro analysis revealed that rNDV-2F2HN expressing human interferon-gamma had potential as a cancer therapeutic tool, particularly for immunized individuals. In the present study, we constructed rNDV-2F2HN expressing the bovine rotavirus antigen VP6 (rNDV-2F2HN-VP6) and evaluated its immune response in mice previously immunized with NDV. Mice primarily inoculated with recombinant wild-type NDV expressing VP6 (rNDV-WT-VP6), followed by a booster inoculation of rNDV-2F2HN-VP6, showed a significantly stronger immune response than that in mice that received rNDV-WT-VP6 as both primary and booster inoculations. Therefore, our findings suggest that robust immunity could be obtained from the effects of chimeric rNDV-2F2HN expressing the same or a different antigen of a particular pathogen as a live attenuated vaccine vector.

Equine Rotavirus A under the One Health Lens: Potential Impacts on Public Health

Group A rotaviruses are a well-known cause of viral gastroenteritis in infants and children, as well as in many mammalian species and birds, affecting them at a young age. This group of viruses has a double-stranded, segmented RNA genome with high genetic diversity linked to point mutations, recombination, and, importantly, reassortment. While initial molecular investigations undertaken in the 1900s suggested host range restriction among group A rotaviruses based on the fact that different gene segments were distributed among different animal species, recent molecular surveillance and genome constellation genotyping studies conducted by the Rotavirus Classification Working Group (RCWG) have shown that animal rotaviruses serve as a source of diversification of human rotavirus A, highlighting their zoonotic potential. Rotaviruses occurring in various animal species have been linked with contributing genetic material to human rotaviruses, including horses, with the most recent identification of equine-like G3 rotavirus A infecting children. The goal of this article is to review relevant information related to rotavirus structure/genomic organization, epidemiology (with a focus on human and equine rotavirus A), evolution, inter-species transmission, and the potential zoonotic role of equine and other animal rotaviruses. Diagnostics, surveillance and the current status of human and livestock vaccines against RVA are also reviewed.

Production of Bovine Rotavirus VP6 Subunit Vaccine in a Transgenic Fodder Crop, Egyptian Clover (Berseem, Trifolium alexandrinum) that Elicits Immune Responses in Rabbit

Group A rotavirus causes acute gastroenteritis in young ones of animals worldwide and is responsible for a high rate of their morbidity and mortality leading to huge economic losses. Developing affordable and safer vaccine on large scale is imperative to reach cattle population worldwide for the long-term control of diarrhea. Rotavirus middle capsid protein layer, VP6, is the most immunogenic and highly conserved protein that induces immune responses against rotavirus. In the present study, bovine group A rotavirus VP6 protein has been expressed for the first time in a highly nutritious and palatable forage crop, Trifolium alexandrinum, using Agrobacterium tumefaciens-mediated stable nuclear transformation. Transgenic nature of the shoots regenerated from cotyledon explants and rooted on hygromycin-containing medium was confirmed by polymerase chain reaction (PCR), Southern blot hybridization, reverse transcription-PCR (RT-PCR) and quantitative real-time PCR (qPCR), and protein expression and quantification by Western blot and enzyme-linked immune-sorbent assay (ELISA), respectively. The transformation efficiency of 2.10% was obtained. The highest amount of VP6 protein produced in a transgenic line was 402 ng/g fresh weights (0.03% of total soluble protein). Oral feeding of transgenic leafy shoots expressing VP6 protein stimulated systemic immunity by inducing significantly higher titers of anti-VP6 serum IgG antibodies in rabbit to reduce rotavirus infection. These transgenic fodder plants offer safer vaccine produced on large scale at low cost with reduced regulatory issues to improve livestock's health and wealth. These plants would be used as alternative to the current live attenuated vaccines to protect young calves against rotavirus infection.

Experimental Senecavirus A Infection of Bovine Cell Lines and Colostrum-Deprived Calves

Senecavirus A (SVA) is a causative agent for vesicular disease in swine, which is clinically indistinguishable from other vesicular diseases of swine including foot-and-mouth disease (FMD). Recently, it was reported that buffalo in Guangdong, China were experiencing clinical symptoms similar to FMD including mouth ulcers and lameness tested positive for SVA. The objective of this study was to determine the susceptibility of cattle (Bos taurus) to SVA infection. Initial in vitro work using the PrimeFlow assay demonstrated that bovine cell lines and peripheral blood mononuclear cells from cattle were susceptible to SVA infection. Subsequently, six colostrum-deprived Holstein calves were challenged with SVA intranasally. No vesicular lesions were observed after challenge. Serum, oral, nasal, and rectal swabs tested for SVA nucleic acid did not support significant viral replication and there was no evidence of seroconversion. Therefore, demonstrating cattle from this study were not susceptible to experimental SVA infection.

Implementation of a pre-calving vaccination programme against rotavirus, coronavirus and enterotoxigenic Escherichia coli (F5) and association with dairy calf survival

Background

Diarrhea is one of the most common diseases and causes of death in calves during the first month of life. Pre-calving vaccination programme (PVP) against the most common diarrhea-causing pathogens could help to avoid this threat if hyperimmune transition milk (TM) is fed to calves throughout the whole susceptibility period. The aim of this retrospective cohort study was to reveal the implementation practices of PVPs in large commercial dairy farms and to compare calf-level mortality hazards during the first year of vaccination (V+ period) and a year before implementing the vaccination programme (V- period). A questionnaire was filled out in 15 large-scale dairy farms in Estonia that used PVP. The farms were assigned into three groups based on compliance with the vaccine directions for use and TM feeding practices. Calf-level time-to-event data was analyzed with an observation period of 21 days and on-farm mortality due to diarrhea being the event of interest.

Results

During the V+ period, a significant decline in diarrhea-induced calf mortality was identified in three out of six herds that followed vaccination instructions and fed TM for at least 14 days. On average, calf mortality hazard due to diarrhea decreased among these herds (hazard rate ratio (HR) = 0.72, 95% confidence interval (CI) 0.63; 0.81). In the group of correctly vaccinating herds where TM was fed for less than 14 days, diarrhea-induced calf mortality decreased in two herds and remained unchanged in two herds with average diarrhea-induced calf mortality hazard declining significantly during the vaccination period (HR = 0.24, 95% CI 0.14; 0.41). Among the three farms that deviated from the vaccination instructions, the average calf mortality hazard increased in the V+ period (HR = 1.61, 95% CI 1.21; 2.14).

Conclusions

This study revealed that implementing a PVP might aid to reduce diarrhea-induced calf mortality in large commercial dairy farms. There is a need to increase veterinarians´ and farmers´ awareness about the importance of including pregnant heifers into the vaccination programme and emphasize the importance of prolonged feeding of hyperimmune TM to calves.

ROTADIAL: The first nanobody-based immunoassay to detect Group A Rotavirus

ROTADIAL is a rapid nanobody (Nb)-based ELISA assay able to identify Rotavirus group A (RVA) in feces from pediatric patients. The assay is based on a sandwich of two patented llama-derived Nbs directed to the inner capsid viral protein VP6 from RVA. Nbs are directed to conformational epitopes of VP6 and recognized all human RVA strains tested, representing ideal reagents for their use in immunodiagnostic tests for RVA detection. All the steps are carried out at room temperature, bringing results in less than two hours. This assay, named ROTADIAL, was validated with a reference panel of feces from pediatric patients from Argentina. The overall sensitivity and specificity of the ROTADIAL test, when compared to a commercial test, was 100 % (100/100) and 99 % (99/100) respectively. ROTADIAL presented optimal analytical performance, being capable of detecting RVA regardless of the presence of other common human enteric infectious agents and is the first RVA-diagnostic assay developed using Nbs, worldwide.

Viral Enteritis in Cattle: To Well Known Viruses and Beyond

Livestock products supply about 13 percent of energy and 28 percent of protein in diets consumed worldwide. Diarrhea is a leading cause of sickness and death of beef and dairy calves in their first month of life and also affecting adult cattle, resulting in large economic losses and a negative impact on animal welfare. Despite the usual multifactorial origin, viruses are generally involved, being among the most important causes of diarrhea. There are several viruses that have been confirmed as etiological agents (i.e., rotavirus and coronavirus), and some viruses that are not yet confirmed as etiological agents. This review summarizes the viruses that have been detected in the enteric tract of cattle and tries to deepen and gather knowledge about them.

Risk factors for neonatal calf diarrhoea and enteropathogen shedding in New Zealand dairy farms

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A cross sectional study of neonatal calf diarrhoea was performed on 97 New Zealand dairy farms.

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Infectious and environmental risk factors for neonatal calf diarrhoea were identified using multivariable analysis.

To investigate the risk factors for neonatal calf diarrhoea, a cross-sectional study was conducted on 97 New Zealand dairy farms. Faecal specimens from 1283 calves were scored as liquid, semi-solid or solid, and analysed for bovine rotavirus (BRV) and coronavirus (BCV), enterotoxigenic K99⁺Escherichia coli (K99), Salmonella spp. and Cryptosporidium parvum. Calf- and farm-level data were collected by means of a questionnaire and the odds of liquid faeces calculated using mixed effects logistic regression models.

Among the infectious agents, only C. parvum (odds ratio [OR] = 2.6; 95% confidence interval [CI], 1.3–5.6; P = 0.02), BRV (OR = 2.7; 95% CI, 1.3–5.9; P = 0.01) and co-infection with more than one agent (compared with mono-infection: OR = 2.5; 95% CI, 1.3–4.8; P = 0.01) were associated with increased odds of liquid faeces in calves which were 9 to 21 days old. Housing of calves in open barns so exposing them to the weather was also associated with increased odds of liquid faeces compared with closed barns (OR = 2.1; 95% CI, 1.1–12.2; P = 0.03). Vaccinating cows against calf enteropathogens (OR = 0.2; 95% CI, 0.1–0.9; P = 0.03), administering waste milk (from mastitis and/or containing antibiotics; OR = 0.4; 95% CI, 0.1–0.8; P = 0.01), the sex of calves (females compared to males OR = 0.2, 95% CI, 0.07–0.7; P < 0.01), and the use of straw for bedding (OR = 0.2; 95% CI, 0.03–0.9; P = 0.03) decreased the odds of liquid faeces. Conversely, in calves that were 1 to 5 days old, only K99 was associated with liquid faeces (OR = 4.6; 95% CI, 1.2–16.1; P = 0.02). In this age group, the odds of liquid faeces were smaller on farms where females took care of the calves, compared with males (OR = 0.4; 95% CI, 0.01–0.9; P = 0.04).

Global distribution of group A rotavirus strains in horses: a systematic review

Group A rotavirus (RVA) is a major cause of diarrhea and diarrhea-related mortality in foals in parts of the world. In addition to careful horse farm management, vaccination is the only known alternative to reduce the RVA associated disease burden on horse farms. The precise evaluation of vaccine effectiveness against circulating strains needs enhanced surveillance of equine RVAs in areas where vaccine is already available or vaccine introduction is anticipated. Therefore, we undertook the overview of relevant information on epidemiology of equine RVA strains through systematic search of public literature databases. Our findings indicated that over 99% of equine RVA strains characterized during the past three decades belonged to two common genotypes, G3P[12] and G14P[12], whereas most of the minority equine RVA strains were probably introduced from a heterologous host by interspecies transmission. These baseline data on RVA strains in horses shall contribute to a better understanding of the spatiotemporal dynamics of strain prevalence in vaccinated and non-vaccinated herds.

Increased accumulation and stability of rotavirus VP6 protein in tobacco chloroplasts following changes to the 5' untranslated region and the 5' end of the coding region

Rotavirus is the main cause of gastroenteritis in children worldwide, and the World Health Organisation has recommended that a rotavirus vaccine should be included in all infant immunization programmes. VP6 is the most immunogenic rotavirus subunit and is a potential target for an oral subunit vaccine. VP6 accumulated at up to 3% of total soluble protein in the young leaves of transplastomic tobacco plants, but the protein was unstable and was lost as the leaves aged. The aim of this study was to alter the 5'-untranslated region (5'-UTR) and the 5' end of the coding region of VP6 cDNA in an attempt to increase the expression and stability of VP6 protein in tobacco chloroplasts. The inclusion of the 5'-UTR from gene 10 of bacteriophage T7 (T7g10) and the addition of 15 nucleotides, encoding five additional amino acid residues, at the 5' end of the coding region increased the expression to >15% of total leaf protein and stabilized the protein in ageing leaves. Plants containing VP6 expression constructs with the rbcL 5'-UTR and with the native VP6 5' end of the coding region produced VP6 protein at only 1.9% of total leaf protein. Both the T7g10 5'-UTR and the additional 15 nucleotides increased transcript accumulation and translational efficiency compared with VP6 constructs containing the rbcL 5'-UTR. The VP6 protein produced from all gene constructs appeared to be susceptible to proteolytic processing at its N-terminal region. However, in all transplastomic lines, VP6 proteins assembled into the trimeric form found in the rotavirus capsid.

Egg yolk IgY: protection against rotavirus induced diarrhea and modulatory effect on the systemic and mucosal antibody responses in newborn calves

Bovine rotavirus (BRV) is an important cause of diarrhea in newborn calves. Local passive immunity is the most efficient protective strategy to control the disease. IgY technology (the use of chicken egg yolk immunoglobulins) is an economic and practical alternative to prevent BRV diarrhea in dairy calves. The aim of this study was to evaluate the protection and immunomodulation induced by the oral administration of egg yolk enriched in BRV specific IgY to experimentally BRV infected calves. All calves in groups Gp 1, 2 and 3 received control colostrum (CC; BRV virus neutralization Ab titer - VN=65,536; ELISA BRV IgG(1)=16,384) prior to gut closure. After gut closure, calves received milk supplemented with 6% BRV-immune egg yolk [(Gp 1) VN=2048; ELISA IgY Ab titer=4096] or non-immune control egg yolk [(Gp 2) VN<4; ELISA IgY Ab titer<4] twice a day, for 14 days. Calves receiving CC only or colostrum deprived calves (CD) fed antibody (Ab) free milk served as controls (Gp 3 and 4, respectively). Calves were inoculated with 10(5.85)focus forming units (FFU) of virulent BRV IND at 2 days of age. Control calves (Gp 3 and 4) and calves fed control IgY (Gp 2) were infected and developed severe diarrhea. Around 80% calves in Gp 1 (IgY 4096) were infected, but they showed 80% (4/5) protection against BRV diarrhea. Bovine RV-specific IgY Ab were detected in the feces of calves in Gp 1, indicating that avian antibodies (Abs) remained intact after passage through the gastrointestinal tract. At post infection day 21, the duodenum was the major site of BRV specific antibody secreting cells (ASC) in all experimental groups. Mucosal ASC responses of all isotypes were significantly higher in the IgY treated groups, independently of the specificity of the treatment, indicating that egg yolk components modulated the immune response against BRV infection at the mucosal level. These results indicate that supplementing newborn calves' diets for the first 14 days of life with egg yolk enriched in BRV-specific IgY represents a promising strategy to prevent BRV diarrhea. Moreover a strong active ASC immune response is induced in the intestinal mucosa following BRV infection after the administration of egg yolk, regardless the specificity of the treatment.