Lipid nanoparticle encapsulated membrane-anchored E2 mRNA vaccine elicits cross-protective immune responses against bovine viral diarrhoea virus infection in calves.

This study aimed to compare the most accurate sample type, test, and timing for detecting bovine viral diarrhea virus (BVDV) in persistently infected (PI) calves at different time points following birth and colostrum intake. Thirteen 18-month-old pregnant heifers were inoculated with BVDV 1b at approximately 75 days of gestation to induce PI offspring. Serum, nasal swabs (NS), and ear notch (EN) samples were collected from PI and negative control calves from birth until day 28 after colostrum intake. Serum immunoglobulin G and BVDV 1b neutralizing antibodies were assessed, and the BVDV detection probability of antigen-capture ELISA (ACE), reverse transcription quantitative PCR (RT-qPCR), virus isolation, and Idexx SNAP test was evaluated using stepwise mixed-effects generalized linear models. 10 PI calves were born. Colostrum-derived BVDV 1b antibodies markedly inhibited BVDV detection, producing false-negative results in up to 100% of samples from PI calves during the first week of age. Total serum immunoglobulin G concentration did not influence BVDV detection. The probability of detecting BVDV in EN samples by RT-qPCR, ACE, and Idexx SNAP increased in PI calves after 7 days of age; however, virus isolation and serum-based tests remained less dependable due to a higher incidence of false negatives. Colostrum-derived BVDV antibodies suppressed BVDV detection in PI calves during the first week of life, leading to false-negative results with various sample types and tests. Evaluating EN samples with RT-qPCR, ACE, or Idexx SNAP after 7 days of age allowed reliable detection of PI calves in the face of colostrum-derived immunity.

Early-life shedding and environmental presence of Mycobacterium avium ssp. paratuberculosis in Chilean dairy calves.

Assessment of endocan as a prognostic biomarker in septic calves with diarrhoea caused by Escherichia coli K99.

IntroductionTritrichomonas foetus is a sexually transmitted flagellate that causes economic loss in the cattle industry throughout the world. In the United States, there are no approved treatments for the parasite. Owing to its transmission strategy, T. foetus typically infects cattle of breeding age. However, in vivo studies of treatment, diagnostic strategies, and vaccination are severely hampered by the maintenance and cost of maintaining adult cattle in research settings. In this study, we investigated the utility of infecting pre-pubescent heifer calves with T. foetus.MethodsFour independent cohorts of cross-bred prepubertal heifer calves were vaginally inoculated with T. foetus trophozoites previously derived from a naturally-infected bull. Infections were assessed by culture, PCR, DNA sequencing, histopathology, gross pathology, and lesion scoring. In addition, reproductive tract tissue was assessed for the presence of galectin-1, a putative receptor for T. foetus trophozoite adhesion.ResultsOur experiments revealed that despite being in anestrus, heifer calves were amenable to infection with trophozoites for as long as 42 days post-infection as determined by PCR and culture of the organism. Histopathology revealed inflammation throughout the reproductive tract of infected calves. Infection resulted in endometritis with lymphoplasmacytic infiltration and demonstrated that trophozoites could pass through the cervix even during anestrus in prepubescent heifers. In addition, immunohistochemistry of the vagina, cervix, and uterus demonstrated robust expression of galectin-1.ConclusionOur experiments demonstrated that prepubertal heifer calves are a suitable natural host model for bovine trichomonosis. This is a significant breakthrough in the field and also has potential for advancing the human trichomoniasis research agenda.

ObjectiveUmbilical infections are a prevalent worldwide health concern in calves. The prevalence and surgical management of umbilical infections in calves were investigated in this study.AnimalsA total of 238 calves with umbilical infections.MethodsMedical records of 238 cases of umbilical infections in calves managed under either range conditions or in smallholder semi-industrial systems in West Azerbaijan, Iran, between March 1998 and July 2020 were analyzed. Data on husbandry type, breed, sex, age, and surgical outcomes were collected in this clinical retrospective study.ResultsThe prevalence of umbilical infections among calves was 8.66%. The frequency of infections in the external portion of the umbilicus was comparable to that of infections involving the intra-abdominal portion. Umbilical abscess was the most common infection in the external portion, while urachus infection predominated in the intra-abdominal portion of the umbilical remnants. Omphalitis was the least frequent infection observed in the newborns and omphaloarteritis was the least common pathology of the umbilical remnants. Calves under the range system had a significantly higher prevalence of umbilical infections compared to those in the semi-industrial system. The frequency of the infection was not affected by gender or breeds.ConclusionUmbilical infection occurred with higher prevalence in calves under 13 weeks of age. The calves managed under range condition exhibited a higher prevalence of the infections with no breed- or gender-related differences. Surgical management was highly successful in treating the affected calves.

Diarrhea is a leading cause of neonatal calf mortality, resulting in substantial economic losses in the livestock industry. Cryptosporidiosis, a major infectious etiology of diarrhea in neonatal calves, is characterized by high mor- bidity. This study aimed to evaluate the acute-phase response in calves with cryptosporidiosis, with a particular focus on the roles of haptoglobin (Hp) and serum amyloid A (SAA) in disease prognosis. A total of 15 calves diagnosed with cryptosporidiosis and 10 healthy calves were included in the study. Clinical assessments and oocyst scoring were conducted on days 0, 3, 5, and 7, alongside evaluation of the hematological and serum biochemical parameters. A standard treatment protocol was administered to calves diagnosed with cryptosporidiosis. The results indicated a significant reduction in oocyst shedding by the end of the study period, following treatment. The mean Hp levels in the infected calves exhibited an increasing trend. However, SAA levels demonstrated fluctuations throughout the monitoring period. In conclusion, while Hp and SAA play roles in the acute-phase response, their utility as prognostic biomarkers for cryptosporidiosis in neonatal calves appears to be limited. Comprehensive studies are needed to better understand the inflammatory process in naturally infected cryptosporidiosis.

Foot and mouth disease (FMD), the “Risk Group 4” animal pathogen, is causing huge economic loss to the livestock owner due to high morbidity and mortality in young calves. Besides vesicular and cardiac lesions, limited studies are available regarding the FMDV induced hepatorenal dysfunction in the naturally infected cattle. Therefore, the present study was undertaken to investigate the hepatorenalopathy in calves naturally infected with FMDV. The serum from the ailing calves (n=12) were assayed for the estimation of hepatorenal function tests and tumour necrosis factor (TNF)-α. The liver and kidneys from the necropsied calves (n=28) were investigated for pathological, immunohistochemical and molecular investigation along with the virus induced apoptotic changes. The affected calves showed clinical signs of high fever, salivation, vesiculo-ulcerative lesion in the buccal mucosa and skin of hoof cleft. The clinically ailing calves showed elevated serum levels of enzymes in the liver and kidneys (alanine transaminase, aspartate aminotransferase, alkaline phosphatase, blood urea nitrogen, urea, creatinine) and cytokine TNF-α. Post-mortem observations showed the classical lesions of acute necrotizing myocarditis, vesicular/ulceration lesions in the buccal mucosa and clefts of hooves, comparable with the FMD virus infection. In addition to that, variably enlarged livers with rounded borders, centrilobular haemorrhage/necrosis with lobulation, multifocal hepatitis and fibrosis along with congested/hemorrhagic and oedematous kidneys were observed in majority of the calves. Microscopically, the classical lesions of vesicular inflammatory oral lesions, acute necrotizing myocarditis and skeletal muscle necrosis (tongue) were prominent. In addition to that, liver showed prominent multifocal centrilobular necrosis and haemorrhage, surrounded by degenerated fat-laden hepatic cells (like hypoxic changes), multifocal periportal infiltration of mononuclear cells, variably bridging fibrosis and increased activity of Kupffer cells in the sinusoids. The kidneys showed vascular changes such as congestion, oedema and haemorrhages, vasculitis, glomerulitis, interstitial nephritis and tubular degeneration. The presence of viral antigens in the hepatocytes and kidney tubular epithelial cells by immunohistochemistry along with associated elevated serum enzymes support the role of FMDV, causing hepatorenal injury/dysfunction. The TdT-mediated dUTP nick-end labeling (TUNEL) assay confirmed that the death of the hepatocytes and tubular epithelial cells is due to apoptosis. The viral genome in both the liver and kidneys was confirmed to be type A FMDV in multiplex-PCR assay. These results provide insights into novel tissue tropisms in the liver and kidneys of young calves with natural FMDV infections. Therefore, therapeutic intervention should be directed to boost the liver and kidneys for better management of the infected cases.

Effect of colostrum replacer containing bovine leukemia virus antibodies on infection and antibody level in young calves.

Foot-and-mouth disease virus alters MUC genes expression and function of goblet cells in the intestines of naturally infected cattle calves.

Mycotic infections in neonatal calves are often undiagnosed but pose significant risks, especially in immunocompromised neonates. In this study, we report a rare case of co-infection with systemic candidiasis and diphtheritic aspergillosis in a 13-day-old female Murrah buffalo calf presented for necropsy at ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly. Gross examination revealed pneumonic changes with a well-demarcated nodule in the right caudal pulmonary lobe. Adherent mycotic pseudo membranes over the tracheal mucosa, and type I b haemorrhagic ulcers in the abomasum were also detected. Histopathological examination revealed fungal pseudo-hyphae, budding yeasts within pulmonary microabscesses, bronchiolar epithelium, and vessels, along with angioinvasion. The abomasum exhibited transmural necrotizing mycotic abomasitis with fungal hyphae invading submucosal vessels. Aseptically collected heart blood and lung tissue samples cultured on Sabouraud Dextrose Agar (SDA) yielded C. tropicalis. Tracheal swabs inoculated on SDA revealed growth of Aspergillus fumigatus and Aspergillus flavus. This study highlights that in calves with immature immune systems, opportunistic fungal infections are more likely, and the risk is further heightened by injudicious alteration of antibiotic regimens and corticosteroid therapy; such practices should be avoided to prevent mixed infections.

Abstract Zoonotic cryptosporidiosis is caused primarily by Cryptosporidium parvum. Within C. parvum, the IIa and IId zoonotic subtype families are the most prevalent. The IId subtype family has emerged in China in recent years, causing outbreaks of cryptosporidiosis in dairy calves. The majority of infection studies have been conducted with IIa subtypes, while the pathogenicity of IId subtypes remains poorly understood. In this study, two IId isolates (IIdA20G1-HLJ and IIdA20G1-HB) from dairy farms in China were used to infect neonatal dairy calves, with a IIa isolate (IIaA17G2R1-Waterborne) from the USA employed as a control. The present study investigated the clinical, parasitological, and pathological characteristics of infected calves. The results demonstrated significantly greater intensity and duration of oocyst shedding in IId-infected calves than in control calves. In addition, the IIdA20G1-HLJ isolate induced peak oocyst shedding of 4.3×107 oocysts per gram of feces (OPG) in calves, with oocyst shedding over 106 OPGs at 5–9 d post-infection. In contrast, the IIaA17G2R1-Waterbrone isolate induced a lower peak oocyst shedding with 8.7×106 OPGs, and oocyst shedding with over 106 OPGs occurred at 2–4 d post-infection. Furthermore, calves infected with the two IId isolates presented more severe clinical signs and 20–25% mortality. Calves recovered from the primary infection with the IIa or IId subtype were resistant to a secondary challenge with the heterologous subtype, suggesting the existence of cross-protection between the IIa and IId subtypes. The present data demonstrate the high pathogenicity of C. parvum IId subtypes in China and the potential cross-protective immunity between the IIa and IId subtypes in calves.

ABSTRACTBackground and Aim:Bovine tuberculosis (bTB), caused by Mycobacterium bovis, remains a significant zoonotic and economic threat globally. Despite the long-standing use of the Bacillus Calmette-Guérin (BCG) vaccine, its inconsistent efficacy and interference with surveillance tests underscore the need for alternative approaches. This study evaluated the safety, immunogenicity, and protective efficacy of a novel influenza vector-based vaccine expressing M. bovis antigens ESAT-6 and TB10.4, formulated with or without an adjuvant.Materials and Methods:Recombinant influenza A viruses expressing ESAT-6 and TB10.4 were constructed using reverse genetics and incorporated into vaccine formulations. Guinea pigs and calves were immunized with adjuvanted and non-adjuvanted formulations, followed by challenge with a virulent M. bovis strain. Safety was assessed through clinical observation and histopathology. Immune responses were monitored using interferon-gamma (IFNγ) enzyme-linked immunosorbent assay, and protection was evaluated through organ damage indices, bacterial load, and survival rates over a 12-month period.Results:Both formulations were safe and well-tolerated in guinea pigs and calves, with no adverse clinical signs. The non-adjuvanted vaccine induced the highest and most sustained IFNγ response, peaking between 2 and 5 months post-vaccination. In guinea pigs, the protection index reached +0.60 lg in the non-adjuvanted group versus +0.2 lg in the adjuvanted group. In calves, lung bacterial load was reduced to 1.83–1.93 lg colony-forming unit (CFU) in vaccinated animals compared with 5.8 lg CFU in unvaccinated controls. Histopathological examination confirmed minimal tissue damage in the vaccinated groups. Both vaccine formulations demonstrated protective efficacy equivalent to or better than BCG, with the non-adjuvanted version showing superior performance.Conclusion:This novel influenza vector-based vaccine expressing ESAT-6 and TB10.4 antigens elicits strong, long-lasting cellular immunity and provides significant protection against M. bovis infection in guinea pigs and calves. The adjuvant-free formulation demonstrated higher immunogenicity, simplified production, and minimal adverse reactions, positioning it as a promising alternative to BCG for bTB control in livestock.

Infectious bovine rhinotracheitis virus (IBRV) is a globally prevalent pathogen that causes respiratory disease in cattle. Emerging evidence suggests that specific bacterial taxa and gut microbial community compositions are strongly associated with viral pathogenesis, by either enhancing or mitigating disease outcomes. This not only impacts the host’s gastrointestinal physiology but also affects distant organs, including the lungs, liver, and brain. However, the impact of IBRV infection on changes in gut microbiota composition and its association with MetaCyc metabolic pathways remains poorly understood. In this study, based on an epidemiological survey of one-month-old Angus calves in a large-scale Angus beef cattle breeding farm consists of four breeding areas located in Maigaiti County of Kashi Prefecture, China. Alterations in the gut microbiota of 10 IBRV-infected Angus calves (IBRV-positive group, P) compared with their 10 healthy counterparts (IBRV-negative group, N), as well as their correlations with MetaCyc metabolic pathways, were investigated using 16S rRNA sequencing. In comparison with N, both Simpson, Shannon and Pielou_e indices of alpha diversity were elevated in P, and the beta diversity showed a marked separation between N and P. The relative abundance of phylum Firmicutes_C was significantly increased, whereas that of phyla Bacteroidota, Cyanobacteria, and Firmicutes_D were reduced in P. The relative abundance of Genera Dialister and Klebsiella were enriched, while that of Lactobacillus and Blautia_A were depleted in P. Four distinct MetaCyc metabolic pathways were significantly altered, DENITRIFICATION-PWY, PWY-6906, and P101-PWY were significantly decreased in P, while PWY-7446 was significantly increased. Correlation analysis showed that in N, Faecalimonas was positively correlated with both P101-PWY and PWY-6906, and Limousia was positively correlated with P101-PWY. Faecalimonas was positively correlated with PWY-7446, and Klebsiella was positively correlated with DENITRIFICATION-PWY in P. Our results reveal that IBRV infection is associated with significant changes in the gut microbial community and its predicted metabolic functions, which may be linked to the host’s systemic response to the infection. This study provides preliminary data on the association between IBRV infection and gut microbiota profiles, laying a theoretical foundation for future investigations into IBRV pathogenesis and potential targeted prevention strategies.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a health risk for humans and other domestic and wildlife species. Recently, North American elk have been identified as seropositive for SARS-CoV-2, thus posing a potential threat to humans and other mammals. In this work, we characterized the peripheral transcriptomic response to experimental SARS-CoV-2 infection in calves and adult elk at different time points. Significantly differentially expressed genes were identified at 2-, 5-, and 14-days post inoculation (pi) for both age groups. Adult elk presented the greatest number of differentially expressed (DE) genes at all time points, including many genes associated with viral response, immune activation, antibody production, as well as genes associated with coronavirus disease (COVID-19), and coronavirus GO terms and KEGG pathways. Calves presented DE genes associated with viral responses at 5 days pi as well as neurodegenerative-associated genes at 14 days pi. Both adults and calves showed predicted activation of the ISGF3 and IFN type I pathways at day 2 pi and, globally, increased activity related to the coronavirus pathway disease at 5 and 14 days pi. Collectively, this work provides valuable data characterizing the cervid immune response of elk to viral diseases as well as the response of wildlife to SARS-CoV-2 infection.

Neospora caninum, as well as Toxoplasma gondii, secrete proteins that facilitate the invasion of host cells and the regulation of host immune response and metabolism. However, the localization of the secretory proteins in infected animal brains has not been studied in detail. Here, we investigate the brain and intracellular distribution of the secretory proteins in experimentally infected mice and naturally infected calves through histopathology and immunohistochemistry (IHC) to detect surface antigen 1 (NcSAG1), cyclophilin (NcCYP), profilin (NcPF), dense granule protein 6 (NcGRA6), and NcGRA7. These methods revealed that numerous tachyzoites positive for NcSAG1, NcCYP, NcPF, NcGRA6, and NcGRA7 were localized in and around the animals’ necrotic lesions, and NcGRA7 was diffusely observed in the necrotic lesions of the infected mice. Moreover, IHC revealed that NcGRA6 and NcGRA7 were distributed in the cytoplasm of infected neurons around the parasites in the infected mice and calves. This suggests that NcGRA6 and NcGRA7 might be directly related to the alteration of neuronal metabolism and activity, and that NcGRA7 might be related to the formation of necrotic lesions.

Gastrointestinal nematodes (GIN) are of major concern in dairy farming, particularly in smallholder systems, because of their impact on the health of the calves and later on their productivity. These infections often occur as co-infections, which can complicate their prevention and treatment. The aim of this study was to conduct fecal egg counts (FEC), genetically identify GIN species, assess species diversity, and identify associated risk factors for GIN infections in dairy calves. Fecal samples were collected from 532 dairy calves across 289 small holder dairy farms. Species identification was achieved through deep amplicon sequencing of the Internal Transcribed Spacer-2 rDNA locus (ITS-2) of first-stage larvae (L1). The mean eggs per gram (EPG) was 62.0 ± 93.0. Most of the calves 64.2% had low-intensity infections (<50 EPG), 28.6% had medium-intensity infections (50–200 EPG), and 7.2% had high-intensity infections (>200 EPG). Next Generation Sequencing analysis identified nine GIN species, with Cooperia punctata (27.8%), Haemonchus placei (26.3%), and Haemonchus contortus (23.6%) being the most prevalent. Co-infections were common, accounting for 69.5% of all infections, with two (40.1%), three (26.9%), and four-species combinations (19.8%) predominating. Male calves showed a significant association with both increased FEC and smaller heart girth, while FEC decreased with age. H. placei and C. punctata were associated with increased FEC, whereas Ostertagia ostertagi (14.5%) and Trichostrongylus colubriformis (8.0%) were associated with decreased heart girth. Calves managed under pasture systems had higher odds of co-infection. This study reveals that GIN infections are highly prevalent in dairy calves, with co-infections being common, and that GIN burden is significantly influenced by calf age, sex, and management system. The Nemabiome tool offers a promising approach to assessing GIN burden and guiding the selection of anthelmintic protocols as part of sustainable farming strategies in tropical regions.

Dopaminergic neuropathology in calves naturally infected with Neospora caninum.

Oxidative and inflammatory status, daily weight gain, intake and feed efficiency on natural congenitally Neospora caninum infected dairy calves.

Bovine alphaherpesvirus 1 (BoHV-1), a significant pathogen, establishes life-long latency in certain neurons. Dexamethasone, a synthetic corticosteroid, consistently induces BoHV-1 reactivation from latency. Glucocorticoid receptor (GR) and dexamethasone transactivate the immediate early transcription unit 1 (IEtu1) promoter, which drives expression of infected cell protein 0 (bICP0) and bICP4. GR also transactivates the bICP0 early (E) promoter via a ligand-independent manner. Notably, GR and DEX induced BoHV-1 replication in non-permissive COS-7 cells. Furthermore, GR and a histone 3 marker, H3K9 acetylation, are associated with active chromatin and occupy the IEtu1 and bICP0 E promoters when latently infected calves are treated with dexamethasone for 3 hours. Conversely, a heterochromatin marker, histone 3 trimethylated at lysine 9, but not GR, occupied these viral promoters during latency. These studies revealed that GR and dexamethasone play crucial roles in chromatin remodeling of IEtu1 and bICP0 E promoters, which correlate with viral replication and reactivation from latency.