Transient loss of Polycomb components induces an epigenetic cancer fate.

Although cancer initiation and progression are generally associated with the accumulation of somatic mutations1,2, substantial epigenomic alterations underlie many aspects of tumorigenesis and cancer susceptibility3-6, suggesting that genetic mechanisms might not be the only drivers of malignant transformation7. However, whether purely non-genetic mechanisms are sufficient to initiate tumorigenesis irrespective of mutations has been unknown. Here, we show that a transient perturbation of transcriptional silencing mediated by Polycomb group proteins is sufficient to induce an irreversible switch to a cancer cell fate in Drosophila. This is linked to the irreversible derepression of genes that can drive tumorigenesis, including members of the JAK-STAT signalling pathway and zfh1, the fly homologue of the ZEB1 oncogene, whose aberrant activation is required for Polycomb perturbation-induced tumorigenesis. These data show that a reversible depletion of Polycomb proteins can induce cancer in the absence of driver mutations, suggesting that tumours can emerge through epigenetic dysregulation leading to inheritance of altered cell fates.

GII.4 human norovirus and G8P[1] bovine-like rotavirus in oysters (Crassostrea gigas) from Argentina.

Bivalve mollusks have been widely recognized as an important source of foodborne virus. The aim of this work was to determine the presence of norovirus (NoV) and rotavirus (RVA) in Pacific cupped oyster (Crassostrea gigas) from Buenos Aires, Argentina. A total of 88 oyster were processed. 7% of pooled samples resulted positive for NoV GII by RT-qPCR. The nucleotide analysis showed that it was closely related to GII.4/Sydney. Regarding RVA, 21% were positive by RT-qPCR targeting the NSP3 gene. RVA from one pool was isolated in cell culture and infective viral particles were evidenced by immunofluorescence. The genotype constellation of RVA/Oyster-wt/Crassostrea gigas_BA/2015/G8P[1] isolated strain was G8-P[1]-I2-R2-C2-M2-A3-N2-T6-E2-H3, which has a bovine-like genome backbone. Notably, RVA possesses an E2 genotype which is different from the characteristic E12 genotype of RVA circulating in animal species from South America. Our findings evidence not only the presence of enteric viruses in oysters from Argentina, but most important the viability of RVA. This result pose the need to implement surveillance programs to prevent potential foodborne viral outbreaks due to the consumption of contaminated shellfish.

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.

Influence of individual or group housing of newborn calves on rotavirus and coronavirus infection during the first 2 months of life.

Bovine rotavirus A (RVA) and bovine coronavirus (CoV) are the two main viral enteropathogens associated with neonatal calf diarrhea. The aim of the present work was to study the impact of group and individual housing systems in the epidemiology of RVA and CoV infection. Eleven calves reared in individual housing (FA) and nine calves in group housing (FB) were monitored during the first 7 weeks of life. Stool and serum samples were screened for RVA and CoV antigens by ELISA. IgG1 antibodies (Ab) to both antigens were also measured. From the 160 fecal samples collected, the proportion of positive samples to RVA and CoV was significantly higher in FB (23.6%) than in FA (9%) (p = 0.03). The geometric mean of colostral IgG1 Ab titers to CoV and RVA in FA (IgG1 anti-CoV 1024 and anti-RVA 1782.9) was lower than in FB (IgG1 anti-CoV 10,321.2 and anti-RVA 4096) at birth. Calves less than 2 weeks of life from FB had a higher risk of being infected by RVA (OR = 4.9; p = 0.01) and CoV (OR = 17.15; p = 0.01) than calves from FA. The obtained results showed that there was higher RVA and CoV shedding in group-housed calves than in individual-housed animals.

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.

On-site detection of equid alphaherpesvirus 3 in perineal and genital swabs of mares and stallions.

Equine coital exanthema (ECE) is an infectious, venereally transmitted muco-cutaneous disease affecting mares and stallions, caused by equid alphaherpesvirus 3 (EHV3). Diagnostic tools for rapid identification of EHV3 are of primary importance to diminish the risk of EHV3 dissemination at the time of breeding. In the last years, it has been shown that the performance of the insulated-isothermal polymerase chain reaction (iiPCR) is comparable to virus isolation, nested PCR and real-time PCR (qPCR) in detecting pathogens of various animal species. Analytical sensitivity and specificity of the iiPCR were compared with a qPCR, using a plasmid containing the target region of the EHV3 glycoprotein G gene and an Argentinian EHV3 isolate (E/9283/07 C3A). In order to evaluate the diagnostic performance of the iiPCR, nucleic acids of 85 perineal and genital swabs (PGS) of mares and stallions were extracted by tacoTM mini and tested by both techniques. EHV3 was detected in 46 and 45 of the 85 PGS by the iiPCR and qPCR, respectively. There was almost perfect agreement between the two diagnostic methods (98.82%; 95% CI: 95.03-100%; κ = 0.98). The iiPCR had a limit of detection of 95.00% at 6 genome equivalents per reaction and a detection endpoint for viral DNA comparable to that of the qPCR, and did not react with six non-targeted equine pathogens. The iiPCR represents a sensitive and specific method for the rapid on-site diagnosis of EHV3 infection. Its routinely implementation in breeding facilities, and artificial insemination and embryo transfer centers, will contribute to prevent the dissemination of this venereal, highly contagious disease in horses.

Prevalence and viability of group A rotavirus in dairy farm water sources.

AIM: To analyse group A rotavirus (RVA) environmental contamination in waters used for calves' consumption and to assess viral viability in dairy farm water sources. METHODS AND RESULTS: We analysed 202 samples of water used for calves' consumption and RVA was detected by RT-qPCR in 35·1% (95% CI: 28·9-42·0%). A marked pattern of seasonality was observed with higher frequency of detection in colder than warmer months (P = 0·002). There was no association between viral load and season or between the number of milking cows in the herd and the detection of RVA in the farm. The viability of the RVA particles detected was confirmed by isolation of RVA in cell culture from 5 of 10 water samples. Furthermore, an RVA waterborne outbreak of neonatal calf diarrhoea was described. CONCLUSIONS: We demonstrate that RVA is frequent in dairy farm waters, and that the virus is infectious and capable of generating a diarrhoea outbreak. SIGNIFICANCE AND IMPACT OF THE STUDY: Neonatal diarrhoea syndrome leads to economic losses to the livestock industry worldwide. To determine transmission routes is essential to take action in this regard and reduce the impact that this syndrome has for the livestock production. The results obtained in this work alert the dairy industry and highlight that mitigation strategies are crucial to improve the microbiological quality of this water.

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.

Comparison of two commercial kits and an in-house ELISA for the detection of equine rotavirus in foal feces.

Group A rotaviruses (RVA) are important infectious agents associated with diarrhea in the young of several animal species including foals. Currently, a variety of diagnosis methods are commercially available, like ELISA, latex agglutination and immunochromatographic assays. These commercial tests are mainly designed for the detection of human RVA; its applicability in veterinary diagnosis has been poorly studied. The aim of this study was to compare the sensitivity and specificity of two commercial diagnostic kits, Pathfinder™ Rotavirus and FASTest Rota® strip, with an in-house KERI ELISA, for the detection of equine RVA. A total of 172 stool samples from Thoroughbred foals with diarrhea were analyzed. The presence of equine RVA in samples in which only one of the three methods showed positive results was confirmed by RT-PCR. A sample was considered "true positive" when RVA was detected by at least two of the methods, and "true negative" when it tested negative by the three assays. Following these criteria, 50 samples were found positive and 122 were found negative, and were handled as reference population for the assay validation. Pathfinder™ Rotavirus assay showed 32% sensitivity and 97% specificity, FASTest Rota® strip, 92% sensitivity and 97% specificity, and KERI ELISA, 76% sensitivity and 93% specificity. Pathfinder™ Rotavirus showed 77%, FASTest Rota® strip 95%, and KERI ELISA 88% accuracy to correctly classify the samples as equine RVA positive or negative. Pathfinder failed specifically to detect equine RVA G3P12I6 genotype; such performance might be related to the specificity of the monoclonal antibody included in this kit. According to our results, differences among VP6 genotypes could influence the sensitivity to detect equine RVA in foal feces, and thus assay validation of diagnostic kits for each species is necessary. In conclusion, FASTest Rota® strip is more suitable than ELISA Pathfinder™ Rotavirus for the screening of rotavirus infection in foals. The KERI ELISA showed an acceptable performance, and could be considered a proper economic alternative for equine RVA diagnosis.

Phylogenetic analyses of typical bovine rotavirus genotypes G6, G10, P[5] and P[11] circulating in Argentinean beef and dairy herds.

Group A rotavirus (RVA) is one of the main causes of neonatal calf diarrhea worldwide. RVA strains affecting Argentinean cattle mainly possess combinations of the G6, G10, P[5] and P[11] genotypes. To determine RVA diversity among Argentinean cattle, representative bovine RVA strains detected in diarrheic calves were selected from a survey conducted during 1997-2009. The survey covered the main livestock regions of the country from dairy and beef herds. Different phylogenetic approaches were used to investigate the genetic evolution of RVA strains belonging to the prevalent genotypes. The nucleotide phylogenetic tree showed that all genotypes studied could be divided into several lineages. Argentinean bovine RVA strains were distributed across multiple lineages and most of them were distinct from the lineage containing the vaccine strains. Only the aminoacid phylogenetic tree of G6 RVA strains maintained the same lineages as observed at the nucleotide level, whereas a different clustering pattern was observed for the aminoacid phylogenetic trees of G10, P[5] and P[11] suggesting that the strains are more closely related at the aminoacid level than G6 strains. Association between P[5] and G6(IV), prevalent in beef herd, and between P[11] and G6(III) or G10 (VI and V), prevalent in dairy herds, were found. In addition, Argentinean G6(III), G10, P[5] and P[11] bovine RVA strains grouped together with human strains, highlighting their potential for zoonotic transmission. Phylogenetic studies of RVA circulating in animals raised for consumption and in close contact with humans, such as cattle, contribute to a better understanding of the epidemiology of the RVA infection and evolution.

Equine G3P[3] rotavirus strain E3198 related to simian RRV and feline/canine-like rotaviruses based on complete genome analyses.

Equine group A rotavirus (RVA) strains are the most important cause of gastroenteritis in equine neonates and foals worldwide, and G3P[12] and G14P[12] are epidemiologically the most important genotypes. The genotype constellation of an unusual Argentinean G3P[3] RVA strain (RVA/Horse-wt/E3198/2008/G3P[3]) detected in fecal samples of a diarrheic foal in 2008 was shown to be G3-P[3]-I3-R3-C3-M3-A9-N3-T3-E3-H6. Each of these genotypes has been found typically in feline and canine RVA strains, and the genotype constellation is reminiscent to those of Cat97-like RVA strains. However, the phylogenetic analyses revealed only a distant relationship between E3198 and known feline, canine and feline/canine-like human RVA strains. Surprisingly, a rather close relationship was found between E3198 and simian RVA strains RVA/Simian-tc/USA/RRV/1975/G3P[3] for at least 5 gene segments. RRV is believed to be a reassortant between a bovine-like RVA strain and a RVA strains distantly related to feline/canine RVA strains. These analyses indicate that E3198 is unlikely to be of equine origin, and most likely represents a RVA interspecies transmitted virus, possibly in combination with one or more reassortments, from a feline, canine or related host species to a horse. Further studies are in progress to evaluate if this strain was a single interspecies transmission event, or if this strain started to circulate in the equine population.

Bovine rotavirus strains circulating in beef and dairy herds in Argentina from 2004 to 2010.

Bovine Group A Rotavirus (RVA) is one of the main causes of neonatal calf diarrhea worldwide. The present study reports the genotyping of bovine RVA strains circulating in Argentinean cattle from 2004 to 2010. Additionally, a new set of typing primers was designed and tested to differentiate between G8 and G6 (lineage III and IV) RVA strains. Bovine RVA was detected in 30% (435/1462) of the tested samples, corresponding to 49% (207/423) of the studied outbreaks with a similar detection rates in beef (53%; 67/127) and dairy herds (52%; 65/126). The RVA strains circulating in Argentinean cattle belonged to the common bovine genotypes G6 (lineages III and IV), G8, G10, P[5] and P[11]. A different RVA G/P-genotype distribution was found between the exploitation types, with the combination G6(IV)P[5] being by fare the most prevalent RVA strain in beef herds (58%), whereas a more even distribution of G6(III)P[11] (15%), G10P[11] (17%), G6(IV)P[5] (14%), and G6(IV)P[11] (6%) RVA strains was detected in dairy herds. G8 RVA strains were found in two dairy farms in calves co-infected with G8+G6(III)P[11]. A high percentage of co-infections and co-circulation of RVA strains with different genotypes during the same outbreak were registered in both exploitation types (20% of the outbreaks from beef herds and 23% from dairy herds), indicating a potential environment for reassortment. This finding is significant because G10P[11] and G6(III)P[11] strains may possess zoonotic potential. Continuous surveillance of the RVA strains circulating in livestock provides valuable information for a better understanding of rotavirus ecology and epidemiology.

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.

Study of the kinetics of antibodies titres against viral pathogens and detection of rotavirus and parainfluenza 3 infections in captive crias of guanacos (Lama guanicoe).

A longitudinal study was conducted to investigate the presence of antibodies (Ab) to Rotavirus (RV), Parainfluenza-3 virus (PI-3), Bovine Herpesvirus-1 (BoHV-1), Bovine Viral Diarrhoea virus (BVDV-1) and Bluetongue virus (BTV) in eleven guanaco's crias (chulengos) relocated from Rio Negro to Buenos Aires Province (Argentina) and reared in captivity for a year in an experimental field. Serum samples were collected periodically to detect the evidence of viral infections. Faecal samples were collected to investigate RV shedding. We detected the evidence of Ab to RV from the beginning of the experience, suggesting the presence of maternal Ab against the virus. RV infection was detected in seven of the eleven chulengos, by seroconversion (4), virus shedding in stools (1) or both (2). In all cases, the RV strain was typed as [P1]G8, the same G/P type combination detected in captive chulengos with acute diarrhoea sampled in Rio Negro, in 2001. In contrast, we could not detect antibodies against PI-3, BoHV-1, BVDV or BT in any of initial samples. No Abs against BoHV-1, BVDV or BTV were detected in the chulengos throughout the study. However, all the chulengos became asymptomatically seropositive to PI-3 by the 7 month after arrival. This study suggest that wild-born guanacos raised in captivity can be relatively susceptible to common livestock viral infections, such as RV and PI-3, which are easily spread among chulengos.

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.

Evaluation of experimental vaccines for bovine viral diarrhea in bovines, ovines and guinea pigs.

The bovine viral diarrhea virus (BVDV) infection control should be based on elimination of persistently infected animals and on immunization through vaccination, to prevent fetal infection. However, the efficacy of inactivated BVDV vaccines is variable due to its low immunogenicity. This study evaluated the humoral immune response against homologous and heterologous strains of 7 inactivated BVDV vaccines, in bovines and two experimental models (ovine and guinea pig) which might be used to test candidate vaccines. Vaccines formulated with BVDV Singer, Oregon, NADL, and multivalent, induced seroconversion in the three animal models studied, reaching antibody titres higher than 2. Vaccine containing 125C -genotype 2- only induced a low antibody response in ovine, while VS-115 NCP vaccine was not immunogenic. Furthermore, bovine sera at 60 dpv presented homologous as well as heterologous antibody response, indicating a high degree of cross-reactivity among the strains studied. However, when bovine sera were tested against the Argentine field strain 00-693, they showed the lowest levels of cross-reactivity, suggesting the need of continued surveillance to identify and characterize emerging field BVDV strains. Finally, optimal correlations between bovine-ovine and bovine-guinea pig models were observed, indicating that two alternative species could replace bovines when testing the immunogenicity of BVDV candidate vaccines.

Evaluation of experimental vaccines for bovine viral diarrhea in bovines, ovines and guinea pigs / Evaluación de vacunas experimentales para la diarrea viral bovina en bovinos, ovinos y cobayos

The bovine viral diarrhea virus (BVDV) infection control should be based on elimination of persistently infected animals and on immunization through vaccination, to prevent fetal infection. However, the efficacy of inactivated BVDV vaccines is variable due to its low immunogenicity. This study evaluated the humoral immune response against homologous and heterologous strains of 7 inactivated BVDV vaccines, in bovines and two experimental models (ovine and guinea pig) which might be used to test candidate vaccines. Vaccines formulated with BVDV Singer, Oregon, NADL, and multivalent, induced seroconversion in the three animal models studied, reaching antibody titres higher than 2. Vaccine containing 125C -genotype 2- only induced a low antibody response in ovine, while VS-115 NCP vaccine was not immunogenic. Furthermore, bovine sera at 60 dpv presented homologous as well as heterologous antibody response, indicating a high degree of cross-reactivity among the strains studied. However, when bovine sera were tested against the Argentine field strain 00-693, they showed the lowest levels of cross-reactivity, suggesting the need of continued surveillance to identify and characterize emerging field BVDV strains. Finally, optimal correlations between bovine-ovine and bovine-guinea pig models were observed, indicating that two alternative species could replace bovines when testing the immunogenicity of BVDV candidate vaccines.

El control del virus de la diarrea viral bovina (VDVB) se basa en la eliminación de animales persistentemente infectados, y la inmunización de hembras para prevenir infecciones fetales. La eficiencia de estas vacunas es variable por su baja inmunogenicidad. Se evaluó la respuesta inmune humoral contra virus homólogos y heterólogos de 7 vacunas experimentales inactivadas del VDVB en bovinos y en dos modelos experimentales (ovinos y cobayos). Las vacunas conteniendo VDVB Singer, Oregon, NADL y polivalentes indujeron seroconversión en los tres modelos y se alcanzaron títulos de anticuerpos mayores de 2. La vacuna con VDVB genotipo 2 VS-115, NCP, no resultó inmunogénica. La vacuna genotipo 2 125C sólo indujo baja respuesta humoral en ovinos, mientras que la VS-115, NCP, no resultó inmunogénica. En bovinos se determinó la respuesta a virus homólogos y heterólogos a 60 dpv, lo que indica un alto grado de inmunidad cruzada entre la mayoría de las cepas estudiadas. Cuando los sueros bovinos fueron ensayados con la cepa de campo de Argentina 00-693, los niveles de reacción cruzada fueron más bajos; esto sugiere la necesidad de una vigilancia epidemiológica sostenida a fin de identificar y caracterizar las cepas emergentes del VDVB. La óptima correlación en el modelo bovino-ovino y bovino-cobayo indica su utilidad para evaluar la inmunogenicidad de vacunas inactivadas de VDVB.

Molecular characterization of bovine rotavirus circulating in beef and dairy herds in Argentina during a 10-year period (1994-2003).

Group A bovine rotavirus (BRV) is one of the main causes of neonatal calf diarrhea. The present study reports the incidence of rotavirus diarrhea and the genotypes of BRV strains circulating in beef and dairy herds from Argentina, during a 10-year period (1994-2003). Group A BRV was detected in 62.5% (250/400) of the total studied cases of diarrhea. Positive cases were analyzed by heminested multiplex RT-PCR for P and G genotypes identification. Sixty percent of them were typed as P[5]G6, 4.4% P[11]G10, 4.4% P[11]G6 and 2.4% P[5]G10. Additionally, 9.2% of the cases were initially typed as G8 combined with P[5] or P[11], but sequence analysis revealed they belonged to genotype G6, lineage Hun4-like. Partial typing was assessed in 12.0% of the cases. One of the partially typed samples was closely related to genotype G15. BRV was detected in 71% and 58% of the outbreaks registered in beef and dairy farms, respectively. A clear differential distribution of G/P types was found according to the herd type. P[5]G6 was the prevalent strain in beef herds, while P[11] was the prevalent P-type in dairy herds (71%), associated in similar proportions with G6 and G10, These findings indicate that BRV genotypes included in the current commercially available rotavirus vaccines (G6, G10, P[5] and P[11]) should protect calves from most Argentinean field strains. Nevertheless, continuous surveillance is necessary to detect the emergence of new variants.

Isolation of shiga toxin-producing Escherichia coli from a South American camelid (Lama guanicoe) with diarrhea.

Shiga toxin-producing Escherichia coli belonging to serotype O26:H11 was isolated from a 2-month-old guanaco with severe watery diarrhea. E. coli colonies carried the stx1 and eae genes, showed localized adherence to HEp-2 cells, and produced enterohemolysin. A serological response to lipopolysaccharide O26 was observed at the onset of diarrhea.