Performance analysis of two immunochromatographic assays for the diagnosis of rotavirus infection.

Group A rotaviruses (RVAs) are the primary cause of acute gastroenteritis (AGE) in young children worldwide. Several commercial tests including latex agglutination, enzyme-linked assays (ELISA) and immunochromatographic tests (ICT) have been developed for the diagnosis of RVA infection. In the present study, the performance of two commercially available one-step chromatographic immunoassays, CerTest Rotavirus+Adenovirus (Biotec S.L, Zaragoza, Spain) and Vikia Rota-Adeno (bioMerieux SA, Lyon, France) were retrospectively evaluated using Real-time PCR as reference test. Re-testing by Real-time PCR of 2096 stool samples of children hospitalized with AGE previously screened by ICTs (1467 by CerTest and 629 by Vikia) allowed to calculate higher sensitivity for Vikia (94% vs 85% of CerTest) and higher specificity for CerTest (93% vs 89% of Vikia). Accordingly, higher Positive Predictive Values (87% vs 78%) and Positive Likelihood Ratios (12.32 vs 8.8) were found for CerTest and lower Negative Predictive Values (91% vs 97%) and Negative Likelihood Ratios (0.16 vs 0.06) for Vikia. However, both CerTest and Vikia showed a substantial agreement (κ=0.79) with the Real-time PCR. A correlation between false negative results by ICTs and high Cycle Threshold values of Real-time PCR, indicative of low viral load, was observed. False positive results by the two ICT assays were not related to Norovirus, Adenovirus or Astrovirus infections, therefore the risk of cross-reactions was excluded. Both CerTest and VIKIA were able to detect the wide range of RVA genotypes circulating over the study period (including G1P[8], G2P[4], G3, G4, G9 and G12P[8]). The results of the present study showed a satisfactory efficacy of the two diagnostic tests analyzed.

Introduction and prolonged circulation of G12 rotaviruses in Sicily.

Genotype G12 strains are now considered to be the sixth most prevalent human rotaviruses worldwide. In two Sicilian cities, Palermo and Messina, surveillance of rotavirus circulation performed since 1985 and 2009, respectively, did not detect G12 strains until 2012. From 2012 to 2014 rotavirus infection was detected in 29·7% of 1647 stool samples collected from children admitted for acute gastroenteritis to three Sicilian hospitals in Palermo, Messina and Ragusa. In 2012, G12P[8] was first detected in Palermo and then in Messina where it represented the second most frequent genotype (20% prevalence) after G1P[8]. Thereafter, G12 strains continued to circulate in Sicily, showing a marked prevalence in Ragusa (27·8%) in 2013 and in Palermo (21%) and Messina (16·6%) in 2014. All but one of the Sicilian G12 strains carried a P[8] VP4 genotype, whereas the single non-P[8] rotavirus strain was genotyped as G12P[9]. Phylogenetic analysis of the VP7 and VP4 sequences allowed distinction of several genetic lineages and separation of the G12P[8] strains into three cluster combinations. These findings indicate independent introductions of G12 rotavirus strains in Sicily in recent years.