OPV strains circulation in HIV infected infants after National Immunisation Days in Bangui, Central African Republic

<p>Abstract</p> <p>Background</p> <p>Humans are the only host of polioviruses, thus the prospects of global polio eradication look reasonable. However, individuals with immunodeficiencies were shown to excrete vaccine derived poliovirus for long periods of time which led to reluctance to prolong the vaccination campaign for fear of this end result. Therefore, we aimed to assess the duration of excretion of poliovirus after the 2001 National Immunization Days according to Human immunodeficiency virus status.</p> <p>Findings</p> <p>Fifty three children were enrolled. Sequential stool samples were collected in between National Immunisation Days rounds and then every month during one year. Children were classified into 2 groups: no immunodepression (n = 38), immunodepression (n = 15) according to CD4+ lymphocytes cells count. Thirteen poliovirus strains were isolated from 11 children: 5 Human immunodeficiency virus positive and 6 Human immunodeficiency virus negative. None of the children excreted poliovirus for more than 4 weeks. The restriction fragment length polymorphism analysis showed that all strains were of Sabin origin including a unique Polio Sabine Vaccine types 2 and 3 (S2/S3) recombinant.</p> <p>Conclusions</p> <p>From these findings we assume that Human immunodeficiency virus positive children are not a high risk population for long term poliovirus excretion. More powerful studies are needed to confirm our findings.</p

Vaccination antipoliomyélitique et émergence de virus recombinants dérivés de souches vaccinales à Madagascar.

International audienceLettre des orateurs de sessions de communications orales en partenaria

Genetic features of polioviruses isolated in Tunisia, 1991-2006.

BACKGROUND: Genetic characterisation of polioviruses remains highly important even in countries where wild poliovirus circulation has been interrupted. Sequence data on representative wild strains from all geographical regions is required for surveillance purposes and surveillance for vaccine-related isolates with increased potential for transmissibility in humans should continue. OBJECTIVE: To report the genetic characteristics of wild and vaccine-related polioviruses isolated in Tunisia from 1991 to 2006. STUDY DESIGN: Wild isolates were sequenced in the VP1 genomic region and compared to each other. Vaccine-related isolates were assessed for genetic recombination by PCR/RFLP and sequence analysis of the 3D region. Recombinant viruses were assessed for genetic drift in the VP1 region. RESULTS: The VP1 sequences of the last wild isolates, all from serotype3, showed 97.7-98.7% nucleotide homology. Nineteen percent of vaccine-related isolates were vaccine/vaccine intertypic recombinants. No recombinant with non-poliovirus enteroviruses was identified. Mutational differences in the VP1 sequences of recombinant viruses ranged from 0.0% to 0.7% indicating a limited replication period. CONCLUSIONS: This study provides sequence data on wild polioviruses from Tunisia/North Africa and shows that in countries with continuous high vaccine coverage transmission of vaccine-related polioviruses is time-limited

Circulation of a type 1 recombinant vaccine-derived poliovirus strain in a limited area in Romania.

International audienceAfter intensive immunisation campaigns with the oral polio vaccine (OPV) as part of the Global Polio Eradication Initiative, poliomyelitis due to wild viruses has disappeared from most parts of the world, including Europe. Here, we report the characterization of a serotype 1 vaccine-derived poliovirus (VDPV) isolated from one acute flaccid paralysis (AFP) case with tetraplegia and eight healthy contacts belonging to the same small socio-cultural group having a low vaccine coverage living in a small town in Romania. The genomes of the isolated strains appeared to be tripartite type 1/type 2/type 1 vaccine intertypic recombinant genomes derived from a common ancestor strain. The presence of 1.2% nucleotide substitutions in the VP1 capsid protein coding region of most of the strains indicated a circulation time of about 14 months. These VDPVs were thermoresistant and, in transgenic mice expressing the human poliovirus receptor, appeared to have lost the attenuated phenotype. These results suggest that small populations with low vaccine coverage living in globally well-vaccinated countries can be the origin of VDPV emergence and circulation. These results reaffirm the importance of active surveillance for acute flaccid paralysis and poliovirus in both polio-free and polio-endemic countries