Shaukat Shahzad, Angez Mehar, Alam Muhammad Masroor, Sharif Salmaan, Khurshid Adnan, Malik Farzana, Rehman Lubna, Zaidi Syed Sohail Zahoor
Department of Virology, National Institute of Health, Chak Shahzad, Islamabad, Pakistan.
PLoS One. 2014 Sep 17;9(9):e107697. doi: 10.1371/journal.pone.0107697. eCollection 2014.
Pakistan and Afghanistan share a long uncontrolled border with extensive population movement on both sides. Wild poliovirus transmission has never been interrupted in this block due to war against terrorism, poor public health infrastructure, misconceptions about polio vaccines and inadequate immunization activities. All these issues complicate the eradication operations and reinforce the complexity of wiping out poliomyelitis from this region. This study illustrates the origins and routes of cross-border wild poliovirus type 1 (WPV1) transmission during 2010-2012 between Pakistan and Afghanistan. Sequence analyses were conducted based on complete VP1 capsid protein sequences for WPV1 study strains to determine the origin of poliovirus genetic lineages and their evolutionary relationships. Phylogenetic tree was constructed from VP1 gene sequences applying Maximum Likelihood method using Kimura 2- parameter model in MEGA program v 5.0. A total of 72 (14.3%) out of 502 wild-type 1 polioviruses were found circulating in border areas of both countries during 2010-2012. Molecular phylogenetic analysis classified these strains in to two sub-genotypes with four clusters and 18 lineages. Genetic data confirmed that the most of WPV1 lineages (12; 66.6%) were transmitted from Pakistan to Afghanistan. However, the genetic diversity was significantly reduced during 2012 as most of the lineages were completely eliminated. In conclusion, Pakistan-Afghanistan block has emerged as a single poliovirus reservoir sharing the multiple poliovirus lineages due to uncontrolled movement of people across the borders between two countries. If it is neglected, it can jeopardize the extensive global efforts done so-far to eradicate the poliovirus infection. Our data will be helpful to devise the preventive strategies for effective control of wild poliovirus transmission in this region.
巴基斯坦和阿富汗有着漫长的未受管控的边境线，两国边境两侧都有大规模的人口流动。由于反恐战争、公共卫生基础设施薄弱、对脊髓灰质炎疫苗存在误解以及免疫活动不足，该地区的野生脊髓灰质炎病毒传播从未被阻断。所有这些问题都使根除行动变得复杂，并加剧了在该地区消灭脊髓灰质炎的难度。本研究阐述了2010 - 2012年期间巴基斯坦和阿富汗之间跨境1型野生脊髓灰质炎病毒（WPV1）传播的起源和途径。基于WPV1研究毒株的完整VP1衣壳蛋白序列进行序列分析，以确定脊髓灰质炎病毒遗传谱系的起源及其进化关系。利用MEGA程序v 5.0中的Kimura 2 - 参数模型，通过最大似然法从VP1基因序列构建系统发育树。在2010 - 2012年期间，502株1型野生脊髓灰质炎病毒中共有72株（14.3%）在两国边境地区传播。分子系统发育分析将这些毒株分为两个亚基因型，包含四个簇和18个谱系。基因数据证实，大多数WPV1谱系（12个；66.6%）是从巴基斯坦传播到阿富汗的。然而，2012年期间遗传多样性显著降低，因为大多数谱系被完全消除。总之，由于两国边境人员不受控制的流动，巴基斯坦 - 阿富汗地区已成为一个共享多种脊髓灰质炎病毒谱系的单一脊髓灰质炎病毒储存库。如果对此加以忽视，可能会危及迄今为止为根除脊髓灰质炎感染所做的广泛全球努力。我们的数据将有助于制定预防策略，以有效控制该地区野生脊髓灰质炎病毒的传播。
