Antibody titers against vaccine and contemporary wild poliovirus type 1 in children immunized with IPV+OPV and young adults immunized with OPV.

In 2010, a type 1 poliovirus outbreak in Congo with 445 lethal cases was caused by a virus that was neutralized by sera of German adults vaccinated with inactivated polio vaccine with a reduced efficiency. This seroprevalence study was done in two cohorts immunized with other vaccination schedules. Russian children aged 3-6 years immunized with a combination of inactivated and live polio vaccines were reasonably well protected against any wild type poliovirus 1, including the Congolese isolate. Adults aged 20-29 years immunized only with live vaccine were apparently protected against the vaccine strain (92% seropositive), but only 50% had detectable antibodies against the Congo-2010 isolate. Both waning immunity and serological divergence of the Congolese virus could contribute to this result.

Molecular epidemiology of echoviruses 11 and 30 in Russia: different properties of genotypes within an enterovirus serotype.

Over 100 known enterovirus serotypes differ in their epidemiological and pathogenic properties. Much less is known about variation of these features on a sub-serotype level, such as genotypes. Echovirus 11 (E11) and E30 are amongst the most frequent causative agents of aseptic meningitis. We studied the molecular epidemiology of these pathogens to evaluate potential epidemiological and pathogenic dissimilarities of their genotypes. The complete VP1 genome region was sequenced for 97 E11 and 62 E30 isolates collected in Russia from 2008 to 2012, and they were studied in comparison with all 140 E11 and 432 E30 sequences available in GenBank. A geographic pattern of genotype prevalence was observed for both types. Russian E11 isolates belonged mainly to A genotype, which is common in Asia, and D5, which is predominant in Europe. For E30, genotype III by classification of Ke et al. (2011), also termed genotype a by Bailly et al. (2009), was endemic in Russia from 2003 to 2012, while it was not detected in Europe and North America during this time. The E30 genotypes VI-B, VI-G, and VI-H (e, f and h) were regularly introduced from different countries, became predominant and vanished after no more than 4years. In addition to geographic patterns, E11 genotypes also differed by isolation source. Genotype A2 viruses were significantly more often found in sewage, compared to genotype D5 that was isolated from both sewage and human samples. In addition, there was evidence of a different capacity for international transfers among E11 GtA subclusters.

Recombination strategies and evolutionary dynamics of the Human enterovirus A global gene pool.

We analysed natural recombination in 79 Human enterovirus A strains representing 13 serotypes by sequencing of VP1, 2C and 3D genome regions. The half-life of a non-recombinant tree node in coxsackieviruses 2, 4 and 10 was only 3.5 years, and never more than 9 years. All coxsackieviruses that differed by more than 7 % of the nucleotide sequence in any genome region were recombinants relative to each other. Enterovirus 71 (EV71), on the contrary, displayed remarkable genetic stability. Three major EV71 clades were stable for 19-29 years, with a half-life of non-recombinant viruses between 13 and 18.5 years in different clades. Only five EV71 strains out of over 150 recently acquired non-structural genome regions from coxsackieviruses, while none of 80 contemporary coxsackieviruses had non-structural genes transferred from the three EV71 clades. In contrast to earlier observations, recombination between VP1 and 2C genome regions was not more frequent than between 2C and 3D regions.