Norovirus infections and seroprevalence of genotype GII.4-specific antibodies in a Spanish population.

Genotype II.4 noroviruses (NoVs) are a leading cause of epidemic acute gastroenteritis in children and adults worldwide. The prevalence of different NoV genotypes causing outbreaks and sporadic cases of acute gastroenteritis in the region of Valencia, Spain, during a 4-year period (2008-11) was investigated. NoVs were detected in 42 out of 55 (76.3%) outbreaks and in 26 out of 332 (7.8%) sporadic cases of acute gastroenteritis. Genogroup GII strains were predominant in outbreaks and sporadic cases. Different genotype GII.4 variants were found (Yerseke_2006a, Den Haag_2006b, Apeldoorn_2007, and New Orleans_2009), with the latter variant detected most frequently (35.3%). A recombinant P domain of the NoV GII.4 Apeldoorn_2007 variant was produced in Escherichia coli and used as the coating antigen in an enzyme immunoassay to survey the IgG antibody seroprevalence against NoV GII.4 in a Spanish population. Baculovirus-expressed virus-like particles (VLPs) of NoV GII.4 Den Haag_2006b variant were also produced and used as antigen to compare seroreactivity. Of the 434 serum specimens analyzed, 429 (98.6%) had antibodies against the P domain. The comparison of reactivities of 30 serum samples to the NoV GII.4 P polypeptide and VLP showed reproducible results with a correlation coefficient of r = 0.794. Titers of antibodies to the P domain increased gradually and significantly with age, reaching the highest levels at the age group of 41-50 years. These results confirm the high prevalence of NoV GII.4 infections in Valencia from early childhood.

Long-term IgG response to porcine Neu5Gc antigens without transmission of PERV in burn patients treated with porcine skin xenografts.

Acellular materials of xenogenic origin are used worldwide as xenografts, and phase I trials of viable pig pancreatic islets are currently being performed. However, limited information is available on transmission of porcine endogenous retrovirus (PERV) after xenotransplantation and on the long-term immune response of recipients to xenoantigens. We analyzed the blood of burn patients who had received living pig-skin dressings for up to 8 wk for the presence of PERV as well as for the level and nature of their long term (maximum, 34 y) immune response against pig Ags. Although no evidence of PERV genomic material or anti-PERV Ab response was found, we observed a moderate increase in anti-αGal Abs and a high and sustained anti-non-αGal IgG response in those patients. Abs against the nonhuman sialic acid Neu5Gc constituted the anti-non-αGal response with the recognition pattern on a sialoglycan array differing from that of burn patients treated without pig skin. These data suggest that anti-Neu5Gc Abs represent a barrier for long-term acceptance of porcine xenografts. Because anti-Neu5Gc Abs can promote chronic inflammation, the long-term safety of living and acellular pig tissue implants in recipients warrants further evaluation.

[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%).

Sequential evolution of genotype GII.4 norovirus variants causing gastroenteritis outbreaks from 2001 to 2006 in Eastern Spain.

Noroviruses are the most common cause of outbreaks of viral gastroenteritis worldwide. Norovirus outbreaks were surveyed in Catalonia and the region of Valencia (Eastern Spain) between January 2001 and December 2006 as part of the European Union funded network "Food-borne viruses in Europe". During this time the etiology and epidemiological features of 194 outbreaks of acute non-bacterial gastroenteritis were investigated and norovirus was identified as causing 169 (87.1%) of them. Molecular epidemiology of viral strains was studied by RT-PCR and sequencing part of the RNA polymerase gene in ORF1 from 153 outbreak strains. The most commonly identified norovirus genotype was GII.4 (71.9% of the characterized outbreak strains), which is also the predominant genotype worldwide. During this survey five genetic variants of GII.4 genotype have been sequentially detected and identified as 1996, 2002, 2004, 2006a, and 2006b variants. The transition from one variant to a new one always took place over a short period of time, and thereafter the replacement of strains circulating previously was observed. These new GII.4 variants may have arisen as a consequence of viral evasion from the host immune responses, although apparently there is a lack of long-term immunity after norovirus infections.

Nasal immunization of mice with a rotavirus DNA vaccine that induces protective intestinal IgA antibodies.

DNA vaccination using a plasmid encoding the rotavirus inner capsid VP6 has been explored in the mouse model of rotavirus infection. BALB/c mice were immunized with a VP6 DNA vaccine by the intramuscular, nasal and oral routes. VP6 DNA vaccination by the nasal and oral routes induced the production of anti-VP6 IgA antibodies by intestinal lymphoid cells. Intramuscular DNA injection stimulated the production of serum anti-VP6 IgG but not serum anti-VP6 IgA antibodies. Protection against shedding of rotaviruses in stools after oral challenge with the murine EDIM rotavirus strain was investigated in the immunized mice. A significant reduction in the level of rotavirus antigen shedding was demonstrated in those mice immunized at mucosal surfaces, both orally and nasally, with the VP6 DNA vaccine. Intramuscular DNA immunization, which elicited serum anti-VP6 IgG responses but not virus-specific intestinal IgA antibodies, did not provide significant protection against rotavirus challenge.

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%).