Limits...
Evolution and circulation of type-2 vaccine-derived polioviruses in Nad Ali district of Southern Afghanistan during June 2009-February 2011.

Sharif S, Abbasi BH, Khurshid A, Alam MM, Shaukat S, Angez M, Rana MS, Zaidi SS - PLoS ONE (2014)

Bottom Line: These cVDPVs showed 97.7%-98.2% nucleotide and 98%-98.7% amino acid homology in VP1 region on comparison with Sabin type 2 reference strain.All these cVDPVs had two signature mutations of neurovirulent phenotypes and 12 additional mutations in P1 capsid region that might also have contributed to increase neurovirulence and replication.We therefore recommend high quality immunization campaigns not only in affected district Nad Ali but also in the bordering areas between Pakistan and Afghanistan to prevent the spread of cVDPVs.

View Article: PubMed Central - PubMed

Affiliation: Department of Virology, National Institute of Health, Islamabad, Pakistan ; Department of Biotechnology, Quaid-e-Azam University, Islamabad, Pakistan.

ABSTRACT
Oral polio vaccine has been used successfully as a powerful tool to control the spread of wild polioviruses throughout the world; however, during replication in under immunized children, some vaccine viruses revert and acquire the neurovirulent phenotypic properties. In this study, we describe the evolution and circulation of Vaccine-Derived Polioviruses (VDPVs) in Helmand province of Afghanistan. We investigated 2646 AFP cases of Afghan children from June 2009-February 2011 and isolated 103 (04%) vaccine viruses, 45(1.7%) wild type polioviruses and six (0.22%) type 2 circulating vaccine-derived polioviruses (cVDPVs). These cVDPVs showed 97.7%-98.2% nucleotide and 98%-98.7% amino acid homology in VP1 region on comparison with Sabin type 2 reference strain. All these cVDPVs had two signature mutations of neurovirulent phenotypes and 12 additional mutations in P1 capsid region that might also have contributed to increase neurovirulence and replication. Phylogenetic analysis revealed that all these viruses were closely related and originated from previously reported Sabin like 2 virus from Pakistan which did not conform to the standard definition of VDPVs at that time. It was also observed that initial OPV dose was administered approximately 9 months prior to the collection of first stool specimen of index case. Our findings support that suboptimal surveillance and low routine immunization coverage have contributed to the emergence and spread of these viruses in Afghanistan. We therefore recommend high quality immunization campaigns not only in affected district Nad Ali but also in the bordering areas between Pakistan and Afghanistan to prevent the spread of cVDPVs.

Show MeSH

Related in: MedlinePlus

All cVDPVs type2 isolated from Nad Ali district of Helmand province are indicated with round circle filled in black color.Other globally reported cVDPVs type 2 has retrieved from GenBank to reconstruct phylogenetic tree from VP1 coding sequences using neighbor-joining algorithm with Kimura 2-parameter substitution model.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3928168&req=5

pone-0088442-g001: All cVDPVs type2 isolated from Nad Ali district of Helmand province are indicated with round circle filled in black color.Other globally reported cVDPVs type 2 has retrieved from GenBank to reconstruct phylogenetic tree from VP1 coding sequences using neighbor-joining algorithm with Kimura 2-parameter substitution model.

Mentions: The phylogenetic tree constructed with previously reported cVDPVs from Spain EU566941, Nigeria DQ890386, Russia AY649327, China FJ898290, Madagascar AM084225, USA DQ890387, Peru DQ890388 and Egypt AF448782) revealed that all Afghan cVDPVs belonged to one lineage that originated from AFG09/1321 (Fig. 1). In turn, this isolate appears to have evolved from Sabin 2 vaccine strain and was marked as the index case for the subsequently circulating VDPVs. The approximate time of initiating OPV infection was calculated by Ks and Kt values and date of specimen collection. Analysis showed that index case (AFG09/1321) had 2.5% and 0.8% Ks and Kt value respectively, therefore the estimated time of initial OPV dose administration was determined to be approximately 9 months before the onset of paralysis.


Evolution and circulation of type-2 vaccine-derived polioviruses in Nad Ali district of Southern Afghanistan during June 2009-February 2011.

Sharif S, Abbasi BH, Khurshid A, Alam MM, Shaukat S, Angez M, Rana MS, Zaidi SS - PLoS ONE (2014)

All cVDPVs type2 isolated from Nad Ali district of Helmand province are indicated with round circle filled in black color.Other globally reported cVDPVs type 2 has retrieved from GenBank to reconstruct phylogenetic tree from VP1 coding sequences using neighbor-joining algorithm with Kimura 2-parameter substitution model.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928168&req=5

pone-0088442-g001: All cVDPVs type2 isolated from Nad Ali district of Helmand province are indicated with round circle filled in black color.Other globally reported cVDPVs type 2 has retrieved from GenBank to reconstruct phylogenetic tree from VP1 coding sequences using neighbor-joining algorithm with Kimura 2-parameter substitution model.
Mentions: The phylogenetic tree constructed with previously reported cVDPVs from Spain EU566941, Nigeria DQ890386, Russia AY649327, China FJ898290, Madagascar AM084225, USA DQ890387, Peru DQ890388 and Egypt AF448782) revealed that all Afghan cVDPVs belonged to one lineage that originated from AFG09/1321 (Fig. 1). In turn, this isolate appears to have evolved from Sabin 2 vaccine strain and was marked as the index case for the subsequently circulating VDPVs. The approximate time of initiating OPV infection was calculated by Ks and Kt values and date of specimen collection. Analysis showed that index case (AFG09/1321) had 2.5% and 0.8% Ks and Kt value respectively, therefore the estimated time of initial OPV dose administration was determined to be approximately 9 months before the onset of paralysis.

Bottom Line: These cVDPVs showed 97.7%-98.2% nucleotide and 98%-98.7% amino acid homology in VP1 region on comparison with Sabin type 2 reference strain.All these cVDPVs had two signature mutations of neurovirulent phenotypes and 12 additional mutations in P1 capsid region that might also have contributed to increase neurovirulence and replication.We therefore recommend high quality immunization campaigns not only in affected district Nad Ali but also in the bordering areas between Pakistan and Afghanistan to prevent the spread of cVDPVs.

View Article: PubMed Central - PubMed

Affiliation: Department of Virology, National Institute of Health, Islamabad, Pakistan ; Department of Biotechnology, Quaid-e-Azam University, Islamabad, Pakistan.

ABSTRACT
Oral polio vaccine has been used successfully as a powerful tool to control the spread of wild polioviruses throughout the world; however, during replication in under immunized children, some vaccine viruses revert and acquire the neurovirulent phenotypic properties. In this study, we describe the evolution and circulation of Vaccine-Derived Polioviruses (VDPVs) in Helmand province of Afghanistan. We investigated 2646 AFP cases of Afghan children from June 2009-February 2011 and isolated 103 (04%) vaccine viruses, 45(1.7%) wild type polioviruses and six (0.22%) type 2 circulating vaccine-derived polioviruses (cVDPVs). These cVDPVs showed 97.7%-98.2% nucleotide and 98%-98.7% amino acid homology in VP1 region on comparison with Sabin type 2 reference strain. All these cVDPVs had two signature mutations of neurovirulent phenotypes and 12 additional mutations in P1 capsid region that might also have contributed to increase neurovirulence and replication. Phylogenetic analysis revealed that all these viruses were closely related and originated from previously reported Sabin like 2 virus from Pakistan which did not conform to the standard definition of VDPVs at that time. It was also observed that initial OPV dose was administered approximately 9 months prior to the collection of first stool specimen of index case. Our findings support that suboptimal surveillance and low routine immunization coverage have contributed to the emergence and spread of these viruses in Afghanistan. We therefore recommend high quality immunization campaigns not only in affected district Nad Ali but also in the bordering areas between Pakistan and Afghanistan to prevent the spread of cVDPVs.

Show MeSH
Related in: MedlinePlus