Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2012 Feb 22:9:51.
doi: 10.1186/1743-422X-9-51.

Genetic relationships and epidemiological links between wild type 1 poliovirus isolates in Pakistan and Afghanistan

Mehar Angez  1 , Shahzad Shaukat, Muhammad M Alam, Salmaan Sharif, Adnan Khurshid, Syed Sohail Zahoor Zaidi
Affiliations

Genetic relationships and epidemiological links between wild type 1 poliovirus isolates in Pakistan and Afghanistan

Mehar Angez et al. Virol J. .

Abstract

Background/aim: Efforts have been made to eliminate wild poliovirus transmission since 1988 when the World Health Organization began its global eradication campaign. Since then, the incidence of polio has decreased significantly. However, serotype 1 and serotype 3 still circulate endemically in Pakistan and Afghanistan. Both countries constitute a single epidemiologic block representing one of the three remaining major global reservoirs of poliovirus transmission. In this study we used genetic sequence data to investigate transmission links among viruses from diverse locations during 2005-2007.

Methods: In order to find the origins and routes of wild type 1 poliovirus circulation, polioviruses were isolated from faecal samples of Acute Flaccid Paralysis (AFP) patients. We used viral cultures, two intratypic differentiation methods PCR, ELISA to characterize as vaccine or wild type 1 and nucleic acid sequencing of entire VP1 region of poliovirus genome to determine the genetic relatedness.

Results: One hundred eleven wild type 1 poliovirus isolates were subjected to nucleotide sequencing for genetic variation study. Considering the 15% divergence of the sequences from Sabin 1, Phylogenetic analysis by MEGA software revealed that active inter and intra country transmission of many genetically distinct strains of wild poliovirus type 1 belonged to genotype SOAS which is indigenous in this region. By grouping wild type 1 polioviruses according to nucleotide sequence homology, three distinct clusters A, B and C were obtained with multiple chains of transmission together with some silent circulations represented by orphan lineages.

Conclusion: Our results emphasize that there was a persistent transmission of wild type 1 polioviruses in Pakistan and Afghanistan during 2005-2007. The epidemiologic information provided by the sequence data can contribute to the formulation of better strategies for poliomyelitis control to those critical areas, associated with high risk population groups which include migrants, internally displaced people, and refugees. The implication of this study is to maintain high quality mass immunization with oral polio vaccine (OPV) in order to interrupt chains of virus transmission in both countries to endorse substantial progress in Eastern-Mediterranean region.

PubMed Disclaimer

Figures

Figure 1
Figure 1
A dendogram summarizing the sequence relationship among wild type1 polioviruses isolated in Pakistan 2005-2007 based on VP1 nucleotide sequences. Tree was constructed by Neighbor-Joining method using Kimura2-parameter model. Isolates are represented by epid no, date of onset and province codes. Codes were mentioned as PAK: Pakistan, AFG: Afghanistan, BN: Balochictan, KP: Khyber Pakhtoonkahw, PB: Punjab, SD: Sindh.
Figure 2
Figure 2
Dendogram of Cluster A summarizing six lineages (a-f) sequence relationship among wild type1 polioviruses isolated in Pakistan 2005-2007 based on VP1 nucleotide sequences. Tree was constructed by Neighbor-Joining method using Kimura2-parameter model. Isolates are represented by epid no, date of onset and province codes. Codes were mentioned as PAK: Pakistan, AFG: Afghanistan, BN: Balochictan, KP: Khyber Pakhtoonkahw, PB: Punjab, SD: Sindh.
Figure 3
Figure 3
Dendogram of Cluster B summarizing three lineages (g-i) sequence relationship among wild type1 polioviruses isolated in Pakistan, 2005-2007 based on VP1 nucleotide sequences. Tree was constructed by Neighbor-Joining method using Kimura2-parameter model. Isolates are indicated by epid no, date of onset and province codes. Codes were mentioned as PAK: Pakistan, AFG: Afghanistan, BN: Balochictan, KP: Khyber Pakhtoonkahw, PB: Punjab, SD: Sindh.
Figure 4
Figure 4
Geographical location of wild type1 polioviruses isolated during 2005-2007 from Pakistan-Afghanistan.
Figure 5
Figure 5
Dendogram of Cluster C summarizing sequence relationship among wild type1 polioviruses isolated in Pakistan 2004-2007 based on VP1 nucleotide sequences. Tree was constructed by Neighbor-Joining method using Kimura2-parameter model. Isolates are indicated by epid no and province codes. Codes were mentioned as PAK: Pakistan, AFG: Afghanistan, BN: Balochictan, KP: Khyber Pakhtoonkahw, PB: Punjab, SD: Sindh.
See this image and copyright information in PMC

References

    1. Global Polio Eradication Initiative. 2009. http://www.polioeradication.org/history.asp
    1. Global Polio Eradication Initiative. 2009. http://www.polioeradication.org/casecount.asp
    1. Centers for Disease Control and Prevention. Progress toward poliomyelitis Eradication--Pakistan and Afghanistan. MMWR. 2008;57(12):315–319. - PubMed
    1. CDC. Progress report toward poliomyelitis eradication Afghanistan and Pakistan, 2009. MMWR. 2010;59:268–272. - PubMed
    1. Global polio eradication initiative strategic plan 2009-2013 frame work document. Geneva: World Health Organization; 2009. http://www.polioeradication.org/content/publications/pilot strategic pla...