The isolation of a capsid intertypic poliovirus recombinant from a child with vaccine-associated paralytic poliomyelitis is described. Virus 31043 had a Sabin-derived type 3-type 2-type 1 recombinant genome with a 5-end crossover point within the capsid coding region. The result was a poliovirus chimera containing the entire coding sequence for antigenic site 3a derived from the Sabin type 2 strain. The recombinant virus showed altered antigenic properties but did not acquire type 2 antigenic characteristics. The significance of the presence in nature of such poliovirus chimeras and the consequences for the current efforts to detect potentially dangerous vaccine-derived poliovirus strains are discussed in the context of the global polio eradication initiative.Poliovirus, the agent responsible for paralytic poliomyelitis, is a human enterovirus member of the family Picornaviridae, a group of nonenveloped positive-strand RNA viruses. The coding region of the genome is preceded by a long 5Ј noncoding region (NCR) of approximately 740 nucleotides that contains important determinants of virulence. The 3Ј end of the genome consists of a short NCR of about 70 nucleotides that is also implicated in RNA replication (33). The coding region is translated as a single polyprotein and is then processed to generate the viral capsid (VP1 to VP4) and the nonstructural proteins. The antigenic determinants for poliovirus-neutralizing antibodies are located on surface-exposed loops in the capsid proteins VP1, VP2, and VP3. Four main antigenic sites have been identified by the use of murine monoclonal antibodies (MAbs) (30).Genomic RNA recombination is a common event during poliovirus evolution. The oral poliovaccine (OPV) consists of live attenuated strains of the three polio serotypes, which replicate in the guts of immunocompetent vaccinees for periods that range between several weeks and 3 months. A high proportion of type 2 and type 3 polio isolates excreted by healthy vaccinees and patients with vaccine-associated paralytic poliomyelitis (VAPP), have been found to be intertypic recombi-

As a result of successful implementation of the measles/rubella elimination program, the etiology of more and more double negative cases remains elusive. The present study determined the role of different viruses as causative agents in measles or rubella suspected cases in Belarus. A total of 856 sera sent to the WHO National Laboratory between 2009 and 2011 were tested for specific IgM antibodies to measles virus (MV), rubella virus (RV) and human parvovirus B19 (B19V). The negatives were further investigated for antibodies to enterovirus (EV) and adenovirus (AdV). Children of up to 3 years were tested for IgM antibodies to human herpesvirus 6 (HHV6). A viral etiology was identified in 451 (52.7%) cases, with 6.1% of the samples being positive for MV; 2.6% for RV; 26.2% for B19V; 9.7% for EV; 4.6% for AdV; and 3.6% for HHV6. Almost all measles and rubella cases occurred during limited outbreaks in 2011 and nearly all patients were at least 15 years old. B19V, EV and AdV infections were prevalent both in children and adults and were found throughout the 3 years. B19V occurred mainly in 3–10 years old children and 20–29 years old adults. EV infection was most common in children up to 6 years of age and AdV was confirmed mainly in 3–6 years old children. HHV6 infection was mostly detected in 6–11 months old infants. Laboratory investigation of measles/rubella suspected cases also for B19V, EV, AdV and HHV6 allows diagnosing more than half of all cases, thus strengthening rash/fever disease surveillance in Belarus.

Human parvovirus B19 (B19V) infection in immunocompetent patients usually has a mild clinical course, but during pregnancy it can cause serious and even fatal complications in the fetus. The most common clinical presentation of B19V infection is erythema infectiosum and in this case laboratory confirmation is required for differentiation from other exanthematous diseases. Measles and rubella negative sera collected in Belarus between 2005 and 2008 from 906 patients with a rash and fever were screened for B19V infection by ELISA. More than 35% of the samples (322/906) were positive for B19V. The proportion ranged from 10.1% in 2008 to 53.2% in 2006 when an outbreak took place in Minsk city. All B19V outbreaks and cluster cases occurred during the winter-spring period, but sporadic cases were recorded basically throughout the year. The majority of the cases (56.5%) occurred among the 2 till 10 year old children, and 27.3% of the cases were observed in adults between 19 and 53 years. All 104 B19V strains sequenced in the NS1/VP1u region belonged to genotype 1 with a maximal genetic distance of 1.75%. The two phylogenetic clusters reflected the geographic origins of the viruses within the country. Forty-two unique nucleotide mutations as compared to sequences downloaded from GenBank were found in the VP1u and NS1 regions; most of these changes were nonsynonymous. This report highlights the importance of B19V infection in patients with a rash and fever in Belarus.

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