Association of passive immunity and genetic composition, health, and performance of tropical dairy calves.

This retrospective cohort study aimed to identify risk factors for the failure of transfer of passive immunity (FPI) in preweaned dairy calves, explore its associations with morbidity, mortality, genetics, and determine a standardized cut-off point for FPI. Analyzing data from 6011 calves, factors such as sire predicted transmitted ability for milk (PTA), birth season, retained placenta (RP), total serum protein concentration (TSP), morbidity (neonatal calf diarrhea - NCD, bovine respiratory disease - BRD, tick-borne disease - TBD), mortality, and average daily weight gain (ADG) were considered. The calves were categorized into predominantly Gyr (PG) and predominantly Holstein (PH) genetic composition groups. Multivariate mixed logistic regression revealed optimal TSP cut-off points for predicting morbidity (7.6 g/dL) and mortality (6.9 g/dL). PH calves exhibited 1.35 times higher odds of FPI and 1.48 times greater odds of disease. Calves from multiparous cows and those born to dams with RP had increased FPI odds. Disease prevalence was 53%, with 41% NCD, 18% BRD, and 10% TBD. Season, parity, PTA, and birth weight were associated with disease odds, though FPI was not a reliable predictor. The mortality percentage was 6%, with PH calves and those with a positive PTA having higher odds. The ADG was 0.64 kg, and FPI-affected calves gained less weight. The study compared and identified various risk factors that potentially impact calf immunity. However, the use of a standardized cut-off point for FPI assessment was not effective in predicting morbidity and mortality at this specific farm.

Development of an IgY-Based Treatment to Control Bovine Coronavirus Diarrhea in Dairy Calves.

Bovine Coronavirus (BCoV) is a major pathogen associated with neonatal calf diarrhea. Standard practice dictates that to prevent BCoV diarrhea, dams should be immunized in the last stage of pregnancy to increase BCoV-specific antibody (Ab) titers in serum and colostrum. For the prevention to be effective, calves need to suck maternal colostrum within the first six to twelve hours of life before gut closure to ensure a good level of passive immunity. The high rate of maternal Ab transfer failure resulting from this process posed the need to develop alternative local passive immunity strategies to strengthen the prevention and treatment of BCoV diarrhea. Immunoglobulin Y technology represents a promising tool to address this gap. In this study, 200 laying hens were immunized with BCoV to obtain spray-dried egg powder enriched in specific IgY Abs to BCoV on a large production scale. To ensure batch-to-batch product consistency, a potency assay was statistically validated. With a sample size of 241, the BCoV-specific IgY ELISA showed a sensitivity and specificity of 97.7% and 98.2%, respectively. ELISA IgY Abs to BCoV correlated with virus-neutralizing Ab titers (Pearson correlation, R2 = 0.92, p < 0.001). Most importantly, a pilot efficacy study in newborn calves showed a significant delay and shorter duration of BCoV-associated diarrhea and shedding in IgY-treated colostrum-deprived calves. Calves were treated with milk supplemented with egg powder (final IgY Ab titer to BCoV ELISA = 512; VN = 32) for 14 days as a passive treatment before a challenge with BCoV and were compared to calves fed milk with no supplementation. This is the first study with proof of efficacy of a product based on egg powder manufactured at a scale that successfully prevents BCoV-associated neonatal calf diarrhea.

Effectiveness of oral electrolyte solutions with different compositions for the treatment of neonatal calves with induced osmotic diarrhea / Eficácia de soluções eletrolíticas orais com diferentes composições no tratamento de bezerros neonatos com diarreia osmótica induzida

In a randomized controlled trial, we evaluated the effects of five oral electrolyte solutions (OESS) with different compositions of water, electrolyte, and acid-base balances of diarrheal neonatal calves. Osmotic diarrhea and dehydration were induced with sucrose in milk, spironolactone, and hydrochlorothiazide for 48 h in thirty 10-day old Holstein healthy calves with 43.5 ± 3.80 kg BW who were fed with natural milk. They were allocated to five treatment groups (n=6) based on the administered OES (commercial: OES A, B, C, D; and non-commercial: OES UEL). On the day of treatment, the calves received 6L of OES in two doses apart from milk intakes. Venous blood samples were collected at -48h (start of induction), -24h, Oh (start of the treatment day), 8h, 16h, 24h, 48h, and 72h. TPP, glucose, D-lactate, L-lactate, pH, pCO2, HCO3, BE, Na, K, CI, SID3, SIG, AG, Atot and percentage change in plasma volume (%PV) were measured or calculated and analyzed by two-way repeated measures ANOVA. All the calves developed osmotic diarrhea, mild to moderate dehydration, hyponatremia, relative hyperchloremia, and moderate to severe metabolic acidosis. The tested OESS were well accepted by the calves and effective in reversing dehydration, electrolyte imbalances, and metabolic acidosis. OES D did not completely correct hyponatremia, and SEO B caused transient hyperglycemia. It has been concluded that all the tested OESS are safe and effective for the treatment of diarrhea in calves with moderate degrees of dehydration and metabolic acidosis, which indicates that they have proper compositions for this purpose.

Em um ensaio clínico controlado e aleatório, foram comparados os efeitos de cinco soluções eletrolíticas orais (SEOs) sobre os equilíbrios hídrico, eletrolítico e ácido-base de bezerros neonatos diarreicos. Diarreia osmótica e desidratação foram induzidas com sacarose no leite, espironolactona e hidroclorotiazida, por 48h, em 30 bezerros Holandeses com 10 dias de idade, 43,5 ± 3,8kg de peso, e alimentados com leite natural. Eles foram distribuídos em cinco grupos de tratamento (n=6) de acordo com a SEO administrada (comercial: SEO A, B, C, D; e não comercial: SEO UEL). No dia do tratamento, os bezerros receberam 6L de SEO em duas doses além da ingestão de leite. Amostras de sangue venoso foram coletadas em -48h (início da indução), - 24h, Oh (início do dia de tratamento), 8h, 16h, 24h, 48h e 72h. PPT, glicose, lactatos Le D, pH, pCO2, HCO3, BE, Na, K, CI, SID3, SIG, AG, Atot e variação percentual no volume plasmático (%VP) foram mensurados ou calculados, e analisados por meio de ANOVA de duas vias de medidas repetidas. Todos os bezerros desenvolveram diarreia osmótica, desidratação leve a moderada, hiponatremia, hipercloremia relativa e acidose metabólica moderada a grave. As SEOs testadas foram bem aceitas pelos bezerros e eficazes para a reversão da desidratação, dos desequilíbrios eletrolíticos e da acidose metabólica. A SEO D não corrigiu completamente a hiponatremia, e a SEO B causou hiperglicemia transitória. Conclui-se que todas as SEOs são eficazes para o tratamento da diarreia em bezerros com graus moderados de desidratação e de acidose metabólica, o que indica que possuem composições adequadas para esse fim.

Determination of an RT-qPCR viral load cutoff point for the etiologic diagnosis of rotavirus A diarrhea in neonate dairy calves.

Rotavirus A (RVA) is amongst the most widespread causes of neonatal calf diarrhea. Because subclinical infections are common, the diagnosis of RVA-induced diarrhea cannot rely solely on molecular viral detection. However, RT-qPCR allows for quantification of RVA shedding in feces, which can be correlated with clinical disease. Here, we determine an optimal cutoff of rotaviral load quantified by RT-qPCR to predict RVA causality in diarrheic neonate calves, using RVA antigen-capture ELISA as reference test. Feces from 328 diarrheic (n = 175) and non-diarrheic (n = 153), <30-day-old dairy calves that had been tested by ELISA and tested positive by RT-qPCR were included. Of 82/328 (25.0%) ELISA-positive calves, 53/175 (30.3%) were diarrheic, whereas 124/153 (81.0%) non-diarrheic calves tested negative by ELISA. The median log10 viral load was significantly higher in diarrheic vs. non-diarrheic and ELISA-positive vs. -negative calves, indicating a higher viral load in diarrheic and ELISA-positive calves. A receiver operating characteristic (ROC) analysis was conducted using the viral loads of the 175 diarrheic calves that had tested either positive (n = 53, cases) or negative (n = 122, controls) by ELISA. The optimal log10 viral load cutoff that predicted RVA causality in diarrheic calves was 9.171. A bootstrapping procedure was performed to assess the out-of-bag performance of this cutoff point, resulting in sensitivity = 0.812, specificity = 0.886, area under the curve = 0.922, and positive and negative diagnostic likelihood ratios of 11.184 and 0.142, respectively. The diagnostic accuracy of the cutoff was excellent to outstanding. This information will help in the interpretation of RVA RT-qPCR results in feces of diarrheic calves submitted for laboratory testing.

Occurrence of Cryptosporidium and other enteropathogens and their association with diarrhea in dairy calves of Buenos Aires province, Argentina.

Cryptosporidiosis of neonatal dairy calves causes diarrhea, resulting in important economic losses. In Argentina, prevalence values of Cryptosporidium spp. and other enteropathogens such as group A rotavirus (RVA), bovine coronavirus (BCoV) and enterotoxigenic Escherichia coli (ETEC, endotoxin STa+), have been independently studied in different regions. However, an integrative epidemiological investigation on large-scale farms has not been carried out. In this study, fecal samples (n = 908) were randomly collected from diarrheic and healthy calves from 42 dairy farms, and analyzed for the presence of Cryptosporidium spp., RVA, BCoV, ETEC (STa+) and Salmonella spp. In all sampled dairy farms, dams had been vaccinated against rotavirus and gram-negative bacteria to protect calves against neonatal diarrhea. The proportion of calves shedding Cryptosporidium spp., RVA, and BCoV in animals younger than 20 days of age were 29.8%, 12.4% and 6.4%, and in calves aged between 21 and 90 days, 5.6%, 3.9%, and 1.8%, respectively. ETEC was absent in the younger, and occurred only sporadically in the older group (0.9%), whereas Salmonella spp. was absent in both. The observed sporadic finding or even absence of bacterial pathogens might be explained by the frequent use of parenteral antibiotics in 25.3% and 6.5% of the younger and the older group of calves, respectively, within 2 days prior to sampling and/or vaccination of dams against gram-negative bacteria. Diarrhea was observed in 28.8% (95% CI, 24.7-32.8%) of the younger calves and 11.7% (95% CI, 9.1-15.5%) of the older calves. Importantly, Cryptosporidium spp. (odds ratio (OR) = 5.7; 95% CI, 3.3-9.9; p < 0.0001) and RVA (OR = 2.5; 95% CI, 1.2-5.1; p < 0.05) were both found to be risk factors for diarrhea in calves younger than 20 days old. Based on its high prevalence and OR, our results strongly suggest that Cryptosporidium spp. is the principal causative factor for diarrhea in the group of neonatal calves, whereas RVA seems to play a secondary role in the etiology of diarrhea in the studied farms, with about three-times lower prevalence and a half as high OR. Furthermore, a coinfection rate of Cryptosporidium spp. and RVA of 3.7% was observed in the group of younger calves, which strengthens the assumption that these events are independent. In contrast, due to a low infection rate of enteropathogens in older calves, mixed infection (<< 1%) was virtually absent in this group.

Salmonelose em bezerros pelo sorovar Dublin no estado do Paraná, Brasil - aspectos clínico-patológicos / Salmonellosis in calves by serovar Dublin in Paraná State, Brazil - clinicopathological aspects

Background: Calf diarrhea remains one of the main diseases affecting the cattle industry. Persistence of this significant problem is associated with the complexity of factors that may be involved (infectious, environmental). An accurate diagnosis is essential for confirming the cause and helping clinicians and cattle producers to apply appropriate strategies in a timely manner. This report describes the histological changes according to the degree of salmonellosis severity, which is a contagious infectious disease caused by Salmonella enterica subsp. enterica, a Gram-negative bacterium, in two beef calves in northern Paraná State, southern Brazil. Cases: Two 90-day-old crossbred Angus and Nellore calves from a beef farm in northern Paraná State were referred to a Veterinary Hospital. Animal 1- developed acute clinical signs (enteritis, ataxia, and muscle rigidity) and died the day after the signs began. Gross findings included heavy and non-collapsed lungs, pulmonary oedema, hepatomegaly, enteritis, and severe diffuse typhlitis. Microscopic analysis revealed severe diffuse necrotic enteritis, typhlitis, severe diffuse interstitial pneumonia, moderate centrilobular hepatic necrosis, mild multifocal nephritis, and severe spleen and lymph node necrosis. Paratyphoid nodules were evidenced on the liver, spleen, and mesenteric lymph nodes. Animal 2- presented apathy, green fibrinous diarrhea, and died three days after the onset of clinical signs. The macroscopic examination showed moderate diffuse enteritis and hepatosplenomegaly. At the microscopic examination, many paratyphoid nodules were observed on the liver, spleen, kidneys, and Peyer's patches, which were associated with intralesional and intravascular bacilli. Additional findings included severe diffuse fibrinous necrotic enteritis with intralesional bacilli, diffuse interstitial pneumonia, multifocal splenic necrosis, lymphoid depletion, and moderate multifocal to coalescent lymphocytic nephritis. Histological Gram staining was performed on selected samples, revealing intralesional Gram-negative bacilli in the liver and intestine. Thus, liver and intestine fragments were used for the microbiological examination. Microbiological culture, isolation and biochemical tests identified the genus Salmonella spp. Then, the colonies were subjected to serological tests for serovar identification, according to ISO/TR 6579-3, which determined the serovar Dublin. After identifying the disease etiological agent, the outbreak was controlled by appropriate antibiotic therapy combined with the correction of sanitary measures. Discussion: Enteritis is a frequent disease in calves, posing a diagnostic challenge in identifying the etiological agent. In the present case, the histological, microbiological, and serological results confirmed a disseminated Salmonella spp. infection. The microscopic findings, such as interstitial pneumonia, fibrinous necrotic enteritis markedly in ileum and paratyphoid nodules in various organs, are the most common aspects of the disease. However, fibrinous cholecystitis, which is considered pathognomonic for salmonellosis, was not observed in this study. Therefore, the absence of such a lesion should not exclude the disease in sick animals. A microscopic injury score was used to determine lesion severity by assigning values from 1 to 4, wherein: 1 = no apparent lesions, 2 = mild lesions, 3 = moderate lesions, and 4 = severe lesions. Both calves were scored as 4. Multiple predisposing factors for the condition were identified in this farm such as different age animals in the same paddock and no specific paddock for sick animals, given that the infectious agent remains in feces, saliva, and nasal discharge. The serovar Dublin induces several clinical signs such as septicemic, respiratory, and enteric manifestations, making a clinical diagnosis a challenge

A new passive immune strategy based on IgY antibodies as a key element to control neonatal calf diarrhea in dairy farms.

BACKGROUND: Neonatal diarrhea remains one of the main causes of morbi-mortality in dairy calves under artificial rearing. It is often caused by infectious agents of viral, bacterial, or parasitic origin. Cows vaccination and colostrum intake by calves during the first 6 h of life are critical strategies to prevent severe diarrhea but these are still insufficient. Here we report the field evaluation of a product based on IgY antibodies against group A rotavirus (RVA), coronavirus (CoV), enterotoxigenic Escherichia coli, and Salmonella sp. This product, named IgY DNT, has been designed as a complementary passive immunization strategy to prevent neonatal calf diarrhea. The quality of the product depends on the titers of specific IgY antibodies to each antigen evaluated by ELISA. In the case of the viral antigens, ELISA antibody (Ab) titers are correlated with protection against infection in calves experimentally challenged with RVA and CoV (Bok M, et al., Passive immunity to control bovine coronavirus diarrhea in a dairy herd in Argentina, 2017), (Vega C, et al., Vet Immunol Immunopathol, 142:156-69, 2011), (Vega C, et al., Res Vet Sci, 103:1-10, 2015). To evaluate the efficiency in dairy farms, thirty newborn Holstein calves were randomly assigned to IgY DNT or control groups and treatment initiated after colostrum intake and gut closure. Calves in the IgY DNT group received 20 g of the oral passive treatment in 2 L of milk twice a day during the first 2 weeks of life. Animals were followed until 3 weeks of age and diarrhea due to natural exposure to infectious agents was recorded during all the experimental time. RESULTS: Results demonstrate that the oral administration of IgY DNT during the first 2 weeks of life to newborn calves caused a delay in diarrhea onset and significantly reduced its severity and duration compared with untreated calves. Animals treated with IgY DNT showed a trend towards a delay in RVA infection with significantly shorter duration and virus shedding compared to control calves. CONCLUSIONS: This indicates that IgY DNT is an effective product to complement current preventive strategies against neonatal calf diarrhea in dairy farms. Furthermore, to our knowledge, this is the only biological product available for the prevention of virus-associated neonatal calf diarrhea.

First report of group A rotavirus and bovine coronavirus associated with neonatal calf diarrhea in the northwest of Argentina.

Group A rotavirus (RVA) and bovine coronavirus (BCoV) are the two main viral enteropathogens associated with neonatal calf diarrhea. The aim of the present survey was to investigate the epidemiology and the role of RVA and BCoV in the presentation of dairy and beef calf diarrhea in Lerma Valley of Salta province, within the Northwest region of Argentina. Stool samples of calves with or without diarrhea younger than 2 months of age were collected from 19 dairy farms and 20 beef farms between the years 2014 and 2016. Stool samples were screened for RVA and BCoV detection by ELISA. Heminested multiplex RT-PCR was used for RVA typing and RT-PCR to confirm BCoV. Positive samples were submitted to sequencing analysis. Bovine RVA and BCoV were circulating in 63% (12/19) and 10.52% (2/19) of the dairy farms, respectively, where 9.5% (46/484) of the calves were positives to RVA and 0.4% (2/484) to BCoV. In beef herds, RVA was detected in 40% (8/20) of the farms and in 6.75% (21/311) of the calves, without positives cases of BCoV. Molecular analysis showed that in dairy farms, G6P[11] and G10P[11] were the prevalent RVA strains, while in beef farms, G10P[11] was the prevalent. The main finding was the detection for the first time of a G15P[11] causing diarrhea in beef calves of Argentina that represents a new alert to be consider for future vaccine updates. Analysis of detected BCoV showed that it is related to the other circulating strains of Argentina.

Passive immunity to control Bovine coronavirus diarrhea in a dairy herd in Argentina / Inmunidad pasiva en el control de la diarrea por coronavirus bovino en un rodeo lechero de Argentina

Bovine coronavirus (BCoV) is a viral enteric pathogen associated with calf diarrhea worldwide being, in Argentina, mostly detected in dairy husbandry systems. The aim of the present work was to study if maternal IgG1 antibodies (Abs) to BCoV acquired by colostrum intake modulate the development of BCoV infection in calves reared in a dairy farm in Argentina. Thirty Holstein calves were monitored during their first 60 days of age. Animals were classified into two groups depending on their initial BCoV IgG1 Ab titers. The "failure of passive transfer" (FPT) group had significantly lower IgG1 Abs to BCoV than the "acceptable passive transfer" (APT) group of calves (log10 1.98 vs. 3.38 respectively) (p<0.0001). These differences were also observed when the total protein levels in both groups were compared (p = 0.0081). Moreover, 71% (5/7) of calves from the FPT group showed IgG1 seroconversion to BCoV compared to 29.4% (5/17) of animals from the APT group. Regarding viral circulation, BCoV was detected in 10% (3/30) of all calves and BCoV IgG1 Ab seroconversion was detected in 42% of the total animals showing that almost half of the calves were infected with BCoV. In conclusion, calves with high titers of specific BCoV IgG1 (≥1024) were mostly protected against viral infection, while animals with low titers of IgG1 (<1024) were mostly infected with BCoV. IgG1 Abs from colostrum origin are critical for prevention of BCoV infection.

El coronavirus bovino (Bovine coronavirus, BCoV) es un enteropatógeno viral asociado a la diarrea neonatal del ternero. El objetivo del presente trabajo fue estudiar si los anticuerpos IgG1 anti-BCoV adquiridos pasivamente mediante el calostro modulan la infección por BCoV en terneros de un rodeo lechero de Argentina. Se monitorearon 30 terneros raza Holstein durante los primeros 60 días de vida. Estos animales fueron clasificados en dos grupos según sus niveles de IgG1 anti-BCoV maternales: grupo con transferencia de inmunidad pasiva aceptable (APT) y grupo con fallas en la transferencia pasiva (FPT). Este último grupo tenía un título de IgG1 significativamente menor comparado con el primer grupo (log10 1,98 vs. 3,38, respectivamente; p< 0,0001). La misma diferencia se observó cuando se compararon los niveles de proteínas séricas totales (p = 0,0081). Además, el 71% (5/7) de los terneros del grupo FPT mostró seroconversión de IgG1, mientras que el 29,4% (5/17) de los terneros del grupo APT la mostró. Con respecto a la circulación viral, se detectó BCoV en el 10% (3/30) de los terneros así como también seroconversión de IgG1 en el 42% del total de los animales, lo que evidencia que aproximadamente la mitad de los terneros se infectaron con BCoV. Este estudio mostró que los terneros con altos títulos de IgG1 específica (≥ 1.024) estuvieron mayormente protegidos contra la infección con BCoV, mientras que los animales con títulos bajos de IgG1 (< 1.024) estuvieron predispuestos a la infección. Esto confirma que los anticuerpos IgG1 calostrales son críticos para la prevención de la infección por este agente viral.

Passive immunity to control Bovine coronavirus diarrhea in a dairy herd in Argentina.

Bovine coronavirus (BCoV) is a viral enteric pathogen associated with calf diarrhea worldwide being, in Argentina, mostly detected in dairy husbandry systems. The aim of the present work was to study if maternal IgG1 antibodies (Abs) to BCoV acquired by colostrum intake modulate the development of BCoV infection in calves reared in a dairy farm in Argentina. Thirty Holstein calves were monitored during their first 60 days of age. Animals were classified into two groups depending on their initial BCoV IgG1 Ab titers. The "failure of passive transfer" (FPT) group had significantly lower IgG1 Abs to BCoV than the "acceptable passive transfer" (APT) group of calves (log10 1.98 vs. 3.38 respectively) (p<0.0001). These differences were also observed when the total protein levels in both groups were compared (p=0.0081). Moreover, 71% (5/7) of calves from the FPT group showed IgG1 seroconversion to BCoV compared to 29.4% (5/17) of animals from the APT group. Regarding viral circulation, BCoV was detected in 10% (3/30) of all calves and BCoV IgG1 Ab seroconversion was detected in 42% of the total animals showing that almost half of the calves were infected with BCoV. In conclusion, calves with high titers of specific BCoV IgG1 (≥1024) were mostly protected against viral infection, while animals with low titers of IgG1 (<1024) were mostly infected with BCoV. IgG1 Abs from colostrum origin are critical for prevention of BCoV infection.

Longitudinal study of bovine rotavirus group A in newborn calves from vaccinated and unvaccinated dairy herds.

Reports of rotavirus excretion in calves usually result from cross-sectional studies, and in face of the conflicting results regarding protection of calves born to vaccinated dams against diarrhea, the aim of the present study was to evaluate rotavirus excretion in dairy calves born to vaccinated or unvaccinated dams, to identify the genotypes of bovine rotavirus group A (RVA) strains isolated from these animals as well as to investigate characteristics of the disease in naturally occurring circumstances throughout the first month of life. Five hundred fifty-two fecal samples were taken from 56 calves, 28 from each farm and, in the vaccinated herd, 11/281 samples (3.91%) taken from six different calves tested positive for RVA while in the unvaccinated herd, 3/271 samples (1.11%) taken from 3 different calves tested positive. The genotyping of the VP7 genes showed 91.2% nucleotide sequence identity to G6 genotype (NCDV strain), and for the VP4 gene, strains from the vaccinated herd were 96.6% related to B223 strain, while strains from the unvaccinated herd were 88% related to P[5] genotype (UK strain). Genotypes found in this study were G6P[11] in the vaccinated herd and G6P[5] in the unvaccinated herd. All calves infected with rotavirus presented an episode of diarrhea in the first month of life, and the discrepancy between the genotypes found in the commercial vaccine (G6P[1] and G10P[11]) and the rotavirus strains circulating in both vaccinated and unvaccinated herds show the importance of keeping constant surveillance in order to avoid potential causes of vaccination failure.

Molecular and antigenic characterization of bovine Coronavirus circulating in Argentinean cattle during 1994-2010.

Bovine coronavirus (BCoV) is an important viral pathogen associated with neonatal calf diarrhea. Our aim was to investigate the incidence of BCoV in diarrhea outbreaks in beef and dairy herds from Argentina during 1994-2010. A total of 5.365 fecal samples from diarrheic calves were screened for BCoV diagnosis by ELISA. The virus was detected in 1.71% (92/5365) of the samples corresponding to 5.95% (63/1058) of the diarrhea cases in 239 beef and 324 dairy farms. The detection rate of BCoV was significantly higher in dairy than in beef herds: 12.13% (29/239) vs. 4.32% (14/324) respectively. Phylogenetic analysis of the hypervariable S1 region of seven representative samples (from different husbandry systems, farm locations and years of sampling) indicated that BCoV strains circulating in Argentinean beef and dairy herds formed a cluster distinct from other geographical regions. Interestingly, Argentinean strains are distantly related (at both the nucleotide and amino acid levels) with the Mebus historic reference BCoV strain included in the vaccines currently available in Argentina. However, Mebus-induced antibodies were capable of neutralizing the BCoV Arg95, a field strain adapted to grow in vitro, and vice versa, indicating that both strains belong to the same CoV serotype reported in cattle. This work represents the first large survey describing BCoV circulation in Argentinean cattle.