SUMMARYMixed infection of MDCK cells with influenza A and influenza B viruses leads to a reduction in the rate of synthesis of haemagglutinin (HA) and nucleoprotein (NP) as compared to their rate of synthesis in cells separately infected with these viruses. The reduction is much stronger for influenza A virus proteins. The synthesis of the nonstructural NS1 protein of both viruses is relatively resistant to the heterotypic interference. The synthesis of virus-specific mRNAs exhibits the same pattern: the formation of the transcripts of HA and NP genes is much more drastically reduced than the synthesis of NS gene transcripts. The effect is strongly dependent on the multiplicity of infection and on the ratio of influenza A and B viruses in the inoculum. Primary transcription in the presence of cycloheximide is almost unchanged in doubly infected cells as compared to single infection, and no indication of differential inhibition has been observed. The results are discussed in connection with the mechanism of heterotypic interference and the regulation of influenza virus protein synthesis.

For the last decade enterovirus outbreaks were registered in all of six districts of Belarus. Two of them, reported in 1997 (in Gomel) and in 2003 (in Minsk), were the most extensive and involved 461 and 1,351 patients respectively. Virus ECHO 30 was identified as the dominant etiologic agent of the outbreak in 1997 whereas co-circulation of ECHO 30, ECHO 6 and Coxsackievirus B5 took place in 2003. Analysis of clinical manifestations during the Minsk outbreak revealed unusually high rate of severe clinical forms of infection including aseptic meningitis, encephalitis and myocardial disorders. Epidemiologic observation was ordinary for enterovirus epidemics in temperate climates: the peak of the outbreak was recorded during summer-autumn period of 2003, and 0-14 years old children predominated. Data from the case-control study indicated that illness was associated with drinking water from community water system. Also the laboratory examination demonstrated contamination of different water samples with the epidemic virus serotypes and sequence analysis showed high level of genetic similarity between waterborne and clinical isolates. For these reasons the outbreak should be classified as a waterborne one. Phylogenetic reconstruction showed that all Belarusian ECHO 30 isolates belong to the major genotype of ECHO 30 which has been circulating for last 15 years in Europe and North America. Viral agents of 2003 were very similar and substantially differed from isolates of 1997. Comparison of nucleotide sequences of isolates from myocarditis patients revealed their considerable genetic similarity with ECHO 30 isolates from patients with aseptic meningitis and from water. The results of the study draw attention to the importance of virological control of tap and bottled water as a relevant measure aimed at reduction of epidemiological risks.

Phenotypically mixed virus yields, obtained by coinfection of MDCK cells with influenza A/WSN/33 and B/Lee/40 viruses, contained both A/WSN/33 and B/Lee/40 NP proteins, as revealed by polyacrylamide gel electrophoresis of the purified '4C-amino acids-labeled virus. Virions were lysed with 0.6 M KCI-Triton X-100 buffer, and nucleocapsids were immunoprecipitated with antibodies against NP protein of influenza A virus. Polyacrylamide gel electrophoresis of the immunoprecipitate revealed NP protein of AIWSN/33 but not of B/Lee/40 virus. However, in similar experiments with the lysates of doubly infected cells, the band of B/Lee/40 NP protein was revealed in the polyacrylamide gel electrophoresis patterns of the immunoprecipitates. In an attempt to analyze the RNA content of the immune complexes, we absorbed the lysates of doubly infected [3H]uridine-labeled cells with protein A-containing Staphylococcus aureus covered with antibodies against the NP protein of influenza A virus. RNA extracted from the immune complexes contained genomic RNA segments of both AIWSN/33 and B/Lee/40 viruses. In control samples containing an artificial mixture of cell lysates separately infected with each virus, the analysis revealed homologous components (i.e., AIWSN/33 NP protein or RNA segments) in the immune complexes. The results suggest the presence of phenotypically mixed nucleocapsids in the cells doubly infected with influenza A and B viruses; in the course of the virion formation, the nucleocapsids lacking the heterologous NP protein are selected.

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SUMMARYThe objective of the study is to analyze molecular epidemiologic surveillance for norovirus infection in Belarus over the past five years (2009)(2010)(2011)(2012)(2013). Laboratory diagnostics was carried out by RT-PCR in 684 patients. Two regions of norovirus genome, localized in RNA-polymerase and capsid protein genes, were used for phylogenetic analysis.Noroviruses were predominant causative agents in adults and second only to rotaviruses in children, they also prevailed among aetiological agents of outbreaks (66.7% of outbreaks). In 2009-2013, the major norovirus genotype was GII.4 (58.3% of all genotyped isolates). Genovariant GII.4 2006b circulated in 2009 and 2010, genovariant GII.4 2009 New Orleans -in 2010and 2012. In addition to GII.4, genotypes GII.6 (16.6%), GII.2 (4.1%), GII.3 (2.2%), and recombinant genotypes GII.g-GII.12 and GII.g-GII.1 (10.4% and 8.3%, respectively) circulated in Belarus.The findings indicate a significant contribution of noroviruses in development of sporadic morbidity and outbreaks of acute gastroenteritis in Belarus. Outbreaks or prominent increases of sporadic morbidity were mostly due to the emergence of a new genotype, or an epidemic genovariant.