Enteric calicivirus and rotavirus infections in domestic pigs.

We report the prevalence of rotavirus and calicivirus infections, along with their respective association with diarrhoea in the porcine population of the region of northern Spain. A total of 221 samples were collected at random from different farms in the region and from the main slaughterhouse facility in the city of Zaragoza. Faecal samples were scored as diarrhoeic or normal and grouped into five groups to match general farm management and age criteria: group I (suckling 0-4 weeks), group II (weaning >4-8 weeks), group III (transition >8-16 weeks), group IV (fattening >16-24 weeks) and group V (adults >24 weeks). Group A rotavirus detection and caliciviruses were investigated by reverse transcription-polymerase chain reaction (RT-PCR). Conventional RT-PCR was performed using primers designed to detect rotavirus group A, caliciviruses and/or human noroviruses. A real-time RT-PCR was carried out using TaqMan probes for genogroups GI and GII of noroviruses. Rotaviruses and caliciviruses were detected with an overall prevalence of 16.7% and 12.2%, respectively. Rotavirus detection in faecal samples was associated with both age and faecal consistency, being more frequent in piglets aged <8 weeks with odds ratios (ORs) equal to 4.3 and 4.9, respectively. Calicivirus shedding in faecal samples was homogenously distributed in all ages, showing no significant association with age or faecal consistency (OR 0.87 and 0.99, respectively). A selection of rotavirus-positive stools were genotyped by multiplex nested PCR. G10, P[6], G12 P[8], G9 [p8] and G4 P[23] genotype combinations were found. Three isolates showed a G3 genotype, but their VP4 gene could not be amplified. It should be noted that the G9 genotype was the major G genotype circulating during that period in Spain. None of the porcine samples was positive for norovirus by real-time RT-PCR, despite the ability of this technique to detect at least 18 human norovirus genotypes. Our data indicate that human noroviruses are unlikely to be circulating in the porcine population; however, sapoviruses have been found. Contrary to rotavirus infection, Calicivirus infection is asymptomatic. Specific primers to detect porcine noroviruses are needed.

[Evaluation of two immunochromatography kits for rapid diagnosis of rotavirus infections]. / Evaluación de dos equipos inmunocromatográficos comerciales para el diagnóstico rápido de la infección por rotavirus.

A prospective study was conducted to evaluate two immunochromatography (ICG) commercial kits for diagnosis of rotavirus infection, VIKIA Rota-Adeno (bioMérieux) and Simple Rota-Adeno (Operon). Reverse transcriptase and polymerase chain reaction (RT-PCR) with specific primers for the VP7 gene of group A rotavirus was used as the reference method. The sensitivity and specificity of the ICG tests compared with those of the reference method were 98.4% and 84.8%, respectively, for Simple Rota-Adeno (Operon), and 100% and 24.2% for VlKIA Rota-Adeno (bioMérieux). It is remarkable the low specificity of the latter method, which yields a high number of false positive results. The predictive value of a positive result by this method was only 71.6%. Most of the detected rotavirus strains corresponded to genotype G9P[8] (65%), followed by G1P[8] (25.4%) and G2P[8] (3.2%).

Evaluación de dos equipos inmunocromatográficos comerciales para el diagnóstico rápido de la infección por rotavirus / Evaluation of two immunochromatography kits for rapid diagnosis of rotavirus infections

Se realizó un estudio prospectivo para evaluar dos equipos comerciales inmunocromatográficos para el diagnóstico rápido de infección por rotavirus a partir de muestras fecales: VIKIA® Rota-Adeno, de bioMérieux, y Simple Rota- Adeno, de Operon. Como método de referencia se utilizó la transcripción reversa y reacción en cadena de la polimerasa (RT-PCR) con cebadores específicos del gen de la proteína VP7 de rotavirus del grupo A. La sensibilidad y la especificidad respecto de la RT-PCR fueron del 98,4% y 84,8% para el Simple Rota-Adeno, y del 100% y 24,2% para el VIKIA® Rota-Adeno. Es de destacar la baja especificidad de este último equipo diagnóstico, que presentó un elevado número de falsos positivos, por lo que el valor predictivo de un resultado positivo es sólo del 71,6%. Asimismo, se identificaron los genotipos de las cepas de rotavirus detectadas; la mayoría de ellas correspondieron al genotipo G9P(8) (65%), seguido de los genotipos G1P(8) (25,4%) y G2P(8) (3,2%).

A prospective study was conducted to evaluate two immunochromatography (ICG) commercial kits for diagnosis of rotavirus infection, VIKIA® Rota-Adeno (bioMérieux) and Simple Rota-Adeno (Operon). Reverse transcriptase and polymerase chain reaction (RT-PCR) with specific primers for the VP7 gene of group A rotavirus was used as the reference method. The sensitivity and specificity of the ICG tests compared with those of the reference method were 98.4% and 84.8%, respectively, for Simple Rota-Adeno (Operon), and 100% and 24.2% for VIKIA® Rota-Adeno (bioMérieux). It is remarkable the low specificity of the latter method, which yields a high number of false positive results. The predictive value of a positive result by this method was only 71.6%. Most of the detected rotavirus strains corresponded to genotype G9P(8) (65%), followed by G1P(8) (25.4%) and G2P(8) (3.2%).

Inhibitory activities of bovine macromolecular whey proteins on rotavirus infections in vitro and in vivo.

Rotavirus is a major cause of infantile viral gastroenteritis and can lead to severe and sometimes lethal dehydration. Previous studies have shown that breast-fed children are better protected against symptomatic infections, and that the milk fat globule protein lactadherin might be at least partly responsible for this effect. In vitro studies have shown that human lactadherin, in contrast to the bovine ortholog, could inhibit rotavirus infectivity, and that bovine MUC1 and a commercially available bovine macromolecular whey protein (MMWP) fraction proved to be effective. The present work describes the versatility of MMWP against the infection of 2 human intestinal cell lines (Caco-2 and FHs 74 Int) by 4 different rotavirus strains (Wa, RRV, YM, RF). Isolation of a protein fraction (CM3Q3) from MMWP that effectively inhibits rotavirus infectivity in vitro is documented. Purification was achieved by monitoring the rotaviral inhibitory activity in fractions obtained from 2 consecutive steps of ion-exchange chromatography. The major component of CM3Q3 was shown to be bovine IgG, and the attenuating capacity of this fraction is most properly linked to this component. The capacity of MMWP, MUC1, lactadherin, and the CM3Q3 fraction to inhibit the infectivity of the murine EMcN rotavirus strain was analyzed in adult BALB/c mice by using 2 different amounts of virus (10 and 100 times more than 50% the viral shedding doses). Only CM3Q3 was able to significantly affect the shedding of rotavirus in the stools of experimentally infected mice when the high viral dose was given. Detection of rotavirus-specific serum antibodies showed that the high dose infected all groups of mice. Experiments with the low dose of virus implied that all the tested milk proteins could affect the viral shedding in stools; in addition, use of MUC1, MMWP, and CM3Q3 prevented the appearance of serum viral antibodies. The advantages of using bovine immunoglobulins to induce passive immunity against rotavirus have been substantially investigated, although studies have mainly focused on the use of derivatives from immunized cows, especially colostrum. This report associates considerable activity against rotavirus infectivity with an ordinary whey product, suggesting that there might be alternatives to colostral-derived products.