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.

Seroprevalence in Household Raised Pigs Indicate High Exposure to GII Noroviruses in Rural Nicaragua.

Information about porcine norovirus (PoNoV), genetically similar to human NoV (HuNoV), is limited from rural areas where household-raised pigs are heavily exposed to faecal material which could facilitate transmission. Histo-blood group antigens (HBGAs) are known susceptibility factors to NoV in humans and in a germfree piglet model but their role in susceptibility in the porcine population remains unknown. This study reports: (i) the seroprevalence and antibody titres to human norovirus (NoV) VLPs in household raised pigs; (ii) the distribution of HBGAs in relation to NoV IgG antibody titres and further characterization by blocking of GII.4 VLP binding to pig gastric mucins (PGM). The majority of pigs were seropositive to all three VLPs tested (58-70%) with seropositivity and cross-reactivity increasing significantly with age. However, pig sera could not block the binding of NoV GII.4 VLPs (Dijon) to PGM suggesting no previous infection with this genotype. The majority of the pigs were H-positive (84%), a susceptibility factor for human infections. IgG antibody titres were however higher in H-negative (GMT = 247) as compared with H-positive (GMT = 57) pigs, but after age stratification, this difference in antibody titres was only observed in pigs ≤1 month of age. In conclusion, serological data show that the porcine population of Nicaragua is highly exposed to NoV infections, and the association to HBGAs warrants further investigation.

Egg yolk IgY antibodies: A therapeutic intervention against group A rotavirus in calves.

Bovine group A rotavirus (RVA) is considered the major cause of diarrhea in intensively reared neonatal calves. Chicken egg yolk antibodies (IgY) are efficient in protecting neonatal calves from RVA diarrhea; however, the value of this intervention in calves once diarrhea has appeared is unclear. The aim of the present study was to evaluate the application of RVA-specific IgY as a passive treatment in those cases. The experimental groups were: G1=RVA-specific IgY treatment; G2=no Ab treatment; and G3=colostrum deprived+no Ab treatment. IgY treatment significantly reduced virus shedding, diarrhea duration and severity compared to G2 and G3 calves. However, it caused a partial suppression of systemic Ab responses to RVA that could be associated with less severe diarrhea. The oral treatment with IgY for 7days was associated with significantly higher antibody secreting cell responses in the calves compared with other groups of animals.

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.

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.

Milk supplemented with immune colostrum: protection against rotavirus diarrhea and modulatory effect on the systemic and mucosal antibody responses in calves experimentally challenged with bovine rotavirus.

Group A bovine rotavirus (BRV) is the major cause of neonatal calf diarrhea worldwide. As a preventive strategy, we evaluated the protection and immunomodulation in two groups of BRV-inoculated calves. All calves received control colostrum (CC; VN=65,536; IgG(1)=16,384) prior to gut closure followed by the milk supplemented with immune colostrum (VN=1,048,576; IgG(1)=262,144), twice a day, for 14 days. Calves received milk supplemented with 0.8% immune colostrum [(Gp 1) VN=16,384; IgG(1)=4096] or milk supplemented with 0.4% immune colostrum [(Gp 2) VN=1024; IgG(1)=1024]. Calves receiving CC or colostrum deprived calves (CD) fed antibody (Ab) free milk served as controls (Gp 3 and 4). Calves were inoculated with virulent BRV IND at 2 days of age. Group 1 calves (milk IgG(1) 4096) showed 80% protection against BRV diarrhea and significantly reduced virus shedding. At 21 post-inoculation days (PID), the antibody secreting cell (ASC) responses of Gp 1 calves were limited mainly to duodenal and jejunal lamina propria (LP) with limited or no responses in systemic sites (spleen and PBL) and mesenteric lymph nodes. The profile of serum and fecal Ab responses as well as the ASC responses was also modulated by the presence of passive IgG(1) Abs and probably other colostrum components, toward higher titers of IgA Ab in serum and feces and a greater number of IgA ASC in the proximal intestine, reflecting positive modulation by colostrum toward this isotype associated with optimal protection of the intestinal mucosa. After challenge, at PID 21, all calves in Gp 1 and 2 were fully protected against diarrhea and only 1 of 5 calves in Gp 1 shed virus asymptomatically, indicating that the passive Ab treatment for 14 days was effective in protecting most of the animals after a first and a second virus exposure. The final outcome was a positive modulation of the mucosal immune responses and a high protection rate against diarrhea and virus shedding during the period of peak susceptibility to BRV infection.

Modulation by colostrum-acquired maternal antibodies of systemic and mucosal antibody responses to rotavirus in calves experimentally challenged with bovine rotavirus.

The effect of colostral maternal antibodies (Abs), acquired via colostrum, on passive protection and development of systemic and mucosal immune responses against rotavirus was evaluated in neonatal calves. Colostrum-deprived (CD) calves, or calves receiving one dose of pooled control colostrum (CC) or immune colostrum (IC), containing an IgG1 titer to bovine rotavirus (BRV) of 1:16,384 or 1:262,144, respectively, were orally inoculated with 105.5 FFU of IND (P[5]G6) BRV at 2 days of age. Calves were monitored daily for diarrhea, virus shedding and anti-BRV Abs in feces by ELISA. Anti-rotavirus Ab titers in serum were evaluated weekly by isotype-specific ELISA and virus neutralization (VN). At 21 days post-inoculation (dpi), all animals were euthanized and the number of anti-BRV antibody secreting cells (ASC) in intestinal and systemic lymphoid tissues were evaluated by ELISPOT. After colostrum intake, IC calves had significantly higher IgG1 serum titers (GMT=28,526) than CC (GMT=1195) or CD calves (GMT<4). After BRV inoculation, all animals became infected with a mean duration of virus shedding between 6 and 10 days. However, IC calves had significantly fewer days of diarrhea (0.8 days) compared to CD and CC calves (11 and 7 days, respectively). In both groups receiving colostrum there was a delay in the onset of diarrhea and virus shedding associated with IgG1 in feces. In serum and feces, CD and CC calves had peak anti-BRV IgM titers at 7 dpi, but IgA and IgG1 responses were significantly lower in CC calves. Antibody titers detected in serum and feces were associated with circulation of ASC of the same isotype in blood. The IC calves had only an IgM response in feces. At 21 dpi, anti-BRV ASC responses were observed in all analyzed tissues of the three groups, except bone marrow. The intestine was the main site of ASC response against BRV and highest IgA ASC numbers. There was an inverse relationship between passive IgG1 titers and magnitude of ASC responses, with fewer IgG1 ASC in CC calves and significantly lower ASC numbers of all isotypes in IC calves. Thus, passive anti-BRV IgG1 negatively affects active immune responses in a dose-dependent manner. In ileal Peyer's patches, IgM ASC predominated in calves receiving colostrum; IgG1 ASC predominated in CD calves. The presence in IC calves of IgG1 in feces in the absence of an IgG1 ASC response is consistent with the transfer of serum IgG1 back into the gut contributing to the protection of the intestinal mucosa.

[Group A bovine rotavirus: diagnosis and antigenic characterization of strains circulating in the Argentine Republic, 1994-1999]. / Rotavirus bovino grupo A: diagnóstico y caracterización antigénica de cepas circulantes en la República Argentina, 1994-1999.

Group A Bovine Rotavirus (BRV) has been identified as a major cause of neonatal diarrhea in cattle. The study was aimed to determine the prevalence of BRV and to antigenically characterize the G-types of circulating strains in dairy and beef herds in Argentina. A total of 1129 stool samples from diarrheic calves was analyzed from 1994 to 1999. The samples were initially screened for RV by ELISA and PAGE, and then G-typed using monoclonal antibodies (Mab) directed against G1, G2, G3, G6 and G10-specific epitopes. Forty percent (452/1129) of the samples were positive for RV by ELISA, while 24.7% (279/1129) were also positive for PAGE. VP7 was detected in the 70.5% (319/452) of the positive samples using a broadly reactive Mab (C60); 32.6% (104/319) were G6, 15.4% (49/319) were G10, and 6% (19/319) were G1. However, 46.1% (147/319) of the samples remained untypable. Rotavirus diarrhea prevalences were comparable in beef and dairy herds (87.3% and a 74.4%, respectively). Finally, G6 was the most prevalent G-type circulating in beef herds while G10 prevailed in dairy herds. A better understanding of RV epidemiology will contribute to the optimization of current vaccines and prevention programs of RV diarrhea in calves.

Rotavirus bovino grupo A: diagnóstico y caracterización antigénica de cepas circulantes en la República Argentina, 1994-1999 / Group A bovine rotavirus: diagnosis and antigenic characterization of strains circulating in the Argentine Republic, 1994-1999

Group A Bovine Rotavirus (BRV) has been identified as a major cause of neonatal diarrhea in cattle. The study was aimed to determine the prevalence of BRV and to antigenically characterize the G-types of circulating strains in dairy and beef herds in Argentina. A total of 1129 stool samples from diarrheic calves was analyzed from 1994 to 1999. The samples were initially screened for RV by ELISA and PAGE, and then G-typed using monoclonal antibodies (Mab) directed against G1, G2, G3, G6 and G10-specific epitopes. Forty percent (452/1129) of the samples were positive for RV by ELISA, while 24.7 (279/1129) were also positive for PAGE. VP7 was detected in the 70.5 (319/452) of the positive samples using a broadly reactive Mab (C60); 32.6 (104/319) were G6, 15.4 (49/319) were G10, and 6 (19/319) were G1. However, 46.1 (147/319) of the samples remained untypable. Rotavirus diarrhea prevalences were comparable in beef and dairy herds (87.3 and a 74.4, respectively). Finally, G6 was the most prevalent G-type circulating in beef herds while G10 prevailed in dairy herds. A better understanding of RV epidemiology will contribute to the optimization of current vaccines and prevention programs of RV diarrhea in calves.(AU)

Rotavirus bovino grupo A: diagnóstico y caracterización antigénica de cepas circulantes en la República Argentina, 1994-1999 / Group A bovine rotavirus: diagnosis and antigenic characterization of strains circulating in the Argentine Republic, 1994-1999

Group A Bovine Rotavirus (BRV) has been identified as a major cause of neonatal diarrhea in cattle. The study was aimed to determine the prevalence of BRV and to antigenically characterize the G-types of circulating strains in dairy and beef herds in Argentina. A total of 1129 stool samples from diarrheic calves was analyzed from 1994 to 1999. The samples were initially screened for RV by ELISA and PAGE, and then G-typed using monoclonal antibodies (Mab) directed against G1, G2, G3, G6 and G10-specific epitopes. Forty percent (452/1129) of the samples were positive for RV by ELISA, while 24.7 (279/1129) were also positive for PAGE. VP7 was detected in the 70.5 (319/452) of the positive samples using a broadly reactive Mab (C60); 32.6 (104/319) were G6, 15.4 (49/319) were G10, and 6 (19/319) were G1. However, 46.1 (147/319) of the samples remained untypable. Rotavirus diarrhea prevalences were comparable in beef and dairy herds (87.3 and a 74.4, respectively). Finally, G6 was the most prevalent G-type circulating in beef herds while G10 prevailed in dairy herds. A better understanding of RV epidemiology will contribute to the optimization of current vaccines and prevention programs of RV diarrhea in calves.

Rotavirus bovino grupo A: diagnóstico y caracterización antigénica de cepas circulantes en la República Argentina, 1994-1999. / [Group A bovine rotavirus: diagnosis and antigenic characterization of strains circulating in the Argentine Republic, 1994-1999]

Group A Bovine Rotavirus (BRV) has been identified as a major cause of neonatal diarrhea in cattle. The study was aimed to determine the prevalence of BRV and to antigenically characterize the G-types of circulating strains in dairy and beef herds in Argentina. A total of 1129 stool samples from diarrheic calves was analyzed from 1994 to 1999. The samples were initially screened for RV by ELISA and PAGE, and then G-typed using monoclonal antibodies (Mab) directed against G1, G2, G3, G6 and G10-specific epitopes. Forty percent (452/1129) of the samples were positive for RV by ELISA, while 24.7

(279/1129) were also positive for PAGE. VP7 was detected in the 70.5

(319/452) of the positive samples using a broadly reactive Mab (C60); 32.6

(104/319) were G6, 15.4

(49/319) were G10, and 6

(19/319) were G1. However, 46.1

(147/319) of the samples remained untypable. Rotavirus diarrhea prevalences were comparable in beef and dairy herds (87.3

and a 74.4

, respectively). Finally, G6 was the most prevalent G-type circulating in beef herds while G10 prevailed in dairy herds. A better understanding of RV epidemiology will contribute to the optimization of current vaccines and prevention programs of RV diarrhea in calves.

First isolation of rotavirus associated with neonatal diarrhoea in guanacos (Lama guanicoe) in the Argentinean Patagonia region.

Group A rotavirus (RV) and coronavirus (CV) are common viral pathogens associated with neonatal diarrhoea in numerous animal species. The purpose of this work was to investigate the presence of these viral agents in two farm populations of captured guanacos (Lama guanicoe) in the Argentinean Patagonia region, that developed severe diarrhoea outbreaks. Stool and serum samples were analysed for RV and bovine CV antigen and antibody enzyme-linked immunosorbent assay. Rotavirus was detected in faeces from two new-born guanacos with acute diarrhoea, one in each farm. After electrophoretic analysis, each isolated strain, showed a distinctive long dsRNA electropherotype characteristic of group A rotaviruses (4:2:3:2). In addition, 95% (38 of 40) of the sampled animals were positive for RV antibodies, suggesting a high prevalence of RV infection in the populations tested. No evidence of CV circulation by antigen or antibody analysis was observed. To our knowledge, this is the first report of the detection and isolation of RV associated with neonatal diarrhoea in Lama guanicoe.

Reduction in morbidity due to diarrhea in nursing beef calves by use of an inactivated oil-adjuvanted rotavirus-Escherichia coli vaccine in the dam.

An outbreak of neonatal diarrhea occurred among beef calves (2000 animals) from one large Argentinian farm in 1985. Rotavirus was detected in 78% (106/136) and enterotoxigenic Escherichia coli in 1.5% of the samples (2/136) obtained from sick calves. In comparison rotavirus was identified in only 1.6% (1/63) of the samples from clinically healthy calves. The rotavirus strain responsible for the outbreak was characterized as serotype 6 belonging to group A. In the following three years the protective capacity of a combined rotavirus-E. coli inactivated vaccine administered to the dams during the last third of the gestation period was evaluated on this farm by comparison of morbidity due to diarrhea in calves from vaccinated vs. placebo cows within the same year. The morbidity due to diarrhea among calves from dams in the vaccinated and placebo groups was 34% and 77%, respectively in 1986; 23% and 47% in 1987, and 15% and 34%, in 1988. In 1987 morbidity of diarrhea in calves born from vaccinated heifers was 54% and 74% in calves from placebo heifers. In 1988 morbidity from diarrhea was 41% and 54%, respectively among calves in these two groups. In all experiments, calves from heifers showed significantly greater morbidity than calves from cows. Differences in diarrhea morbidity between the vaccinated and placebo groups were statistically significant (P less than 0.05). Additional studies showed that the diarrhea had a significant influence (P less than 0.05) on the average live weight of the calves at weaning (5 to 7 months) with an average weight loss of 7.8 kg per calf among the calves affected with diarrhea.