Surveillance of human rotaviruses in 2007-2011, Hungary: exploring the genetic relatedness between vaccine and field strains.

BACKGROUND: The availability of rotavirus vaccines has resulted in an intensification of post vaccine strain surveillance efforts worldwide to gain information on the impact of vaccines on prevalence of circulating rotavirus strains. OBJECTIVES: In this study, the distribution of human rotavirus G and P types in Hungary is reported. In addition, the VP4 and VP7 genes of G1P[8] strains were sequenced to monitor if vaccine-derived strains were introduced and/or some strains/lineages were selected against. STUDY DESIGN: The study was conducted in 8 geographic areas of Hungary between 2007 and 2011. Rotavirus positive stool samples were collected from diarrheic patients mostly <5 years of age. Viral RNA was amplified by multiplex genotyping RT-PCR assay, targeting the medically most important G and P types. When needed, sequencing of the VP7 and VP4 genes was performed. RESULTS: In total, 2380 strains were genotyped. During the 5-year surveillance we observed the dominating prevalence of genotype G1P[8] (44.87%) strains, followed by G4P[8] (23.4%), G2P[4] (14.75%) and G9P[8] (6.81%) genotypes. Uncommon strains were identified in a low percentage of samples (4.12%). Phylogenetic analysis of 318 G1P[8] strains identified 55 strains similar to the Rotarix strain (nt sequence identities; VP7, up to 97.9%; VP4, up to 98.5%) although their vaccine origin was unlikely. CONCLUSIONS: Current vaccines would have protected against the majority of identified rotavirus genotypes. A better understanding of the potential long-term effect of vaccine use on epidemiology and evolutionary dynamics of co-circulating wild type strains requires continuous strain surveillance.

[Post vaccination rotavirus surveillance in Hungary, in 2007]. / Posztvakcinációs rotavírus-surveillance Magyarországon, 2007.

Vaccination is the main strategy to control severe dehydrating gastroenteritis caused by rotaviruses in early childhood. The availability of new generation rotavirus vaccines has led to an intensification of strain surveillance worldwide, in part, to gauge the impact of the possible vaccine-driven immune selection of wild-type rotavirus strains. In the present study, authors describe the strain prevalence data obtained in 2007, with the involvement of different regions of Hungary. Genomic RNA was extracted from rotavirus-positive stool samples collected mainly from children and then subjected to genotyping using multiplex RT-PCR assay. Type-specific primers targeted G1 to G4, G6, G8 to G10, and G12 VP7 specificities, and P[4], P[6], and P[8] to P[11] VP4 specificities were used. Out of 489 rotavirus-positive specimens, collected from 482 patients, 466 and 474 were successfully G and P typed, respectively, and both G and P type specificities could be assigned for 457 strains. Prevalence data showed the predominance of G4P[8] (31.5%) strains, followed by G1P[8] (28.3%), G2P[4] (19.3%), and G9P[8] (10.2%). Minority strains were G1P[4] (0.4%), G2P[8] (1.3%), G3P[9] (0.2%), G4P[6] (0.7%), G6P[9] (0.4%), G8P[8] (0.2%), G9P[4] (0.2%), G9P[6] (0.8%), and G12P[8] (0.4%). Mixed infections were found in 1.2% of the samples, while 4.9% remained partially or fully non-typified. Our data indicate that the antigen specificities of medically important rotavirus strains identified in this 1-year study are well represented in the vaccines available in the pharmaceutical private market in Hungary. Depending on the vaccination coverage achievable in the forthcoming years, the post-vaccination rotavirus strain surveillance may allow us to gain comprehensive information on the impact of rotavirus vaccines on the prevalence of circulating rotavirus strains.

First detection of P[6],G9 rotaviruses in Hungary--an imported strain from India?

EuroRotaNet was launched to monitor rotavirus strain prevalence during and after introduction of rotavirus vaccines in Europe. In early 2007, we detected P[6],G9 rotaviruses to appear in Hungary, representing the first documented occurrence of this strain in our surveillance area. Epidemiologic data suggested that this strain was introduced from India.

[EuroRotaNet--European rotavirus strain surveillance network established with Hungarian participation]. / Hazai részvétellel megalakult az Európai Rotavírus-törzs-figyelô Hálózat (EuroRotaNet).

Group A rotaviruses are the most common cause of severe gastroenteritis worldwide. The incidence and distribution of group A rotavirus sero/genotypes varies between geographical areas during a rotavirus season, and from one season to the next. In addition, cocirculation of genetically diverse multitypic rotaviruses and of intratypic variants in any one place and time is common. Assuming widespread use of rotavirus vaccine in the near future, comprehensive surveillance of natural rotavirus infections is vital. EuroRotaNet has been established in order to gather comprehensive information on the rotavirus types co-circulating throughout Europe. The main objectives of the network are to (i) develop methods and algorithms for effective rotavirus strain typing and characterisation, (ii) describe in detail the molecular epidemiology of rotavirus infections in Europe, (iii) monitor the effectiveness of current genotyping methods and respond to changes associated with genetic drift and shift, and (iv) monitor the emergence and spread of novel rotavirus strains within Europe. This infrastructure may serve as a platform for future surveillance activities and nested studies for evaluating the effectiveness of a rotavirus vaccine in the general population. Studies to monitor the reduction in disease associated with common rotavirus types, the possible vaccine-induced emergence of antibody escape mutants of genotypes other than those included in the vaccine and of reassortment between vaccine and naturally circulating wildtype strains are required.