Virology Department, National Institute of Health Park Road, Chak Shahzad, Islamabad 45500, Pakistan.
Virol J. 2012 Feb 22;9:51. doi: 10.1186/1743-422X-9-51.
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.
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.
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.
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.
背景/目的：自 1988 年世界卫生组织开始全球根除行动以来，一直在努力消除野生脊灰病毒的传播。自那时以来，脊灰的发病率已大幅下降。然而，血清型 1 和 3 仍在巴基斯坦和阿富汗地方性流行。这两个国家构成了一个单一的流行病学区域，代表着脊灰病毒传播的三个剩余主要全球储存库之一。在这项研究中，我们使用遗传序列数据来调查 2005-2007 年期间来自不同地点的病毒之间的传播联系。
为了寻找野生 1 型脊灰病毒循环的起源和途径，从急性弛缓性麻痹 (AFP) 患者的粪便样本中分离出脊灰病毒。我们使用病毒培养、两种同种型分化方法 PCR、ELISA 来表征疫苗或野生 1 型，并对脊灰病毒基因组的整个 VP1 区进行核酸测序，以确定遗传相关性。
对 111 株野生 1 型脊灰病毒分离株进行核苷酸测序，以研究遗传变异。考虑到序列与 Sabin 1 的 15%差异，MEGA 软件的系统发育分析显示，许多遗传上不同的野生 1 型脊灰病毒株在该地区本土存在的 SOAS 基因型之间存在活跃的国与国之间和国内传播。根据核苷酸序列同源性将野生 1 型脊灰病毒分组，得到三个不同的簇 A、B 和 C，以及一些由孤立谱系代表的沉默循环。
我们的结果强调，2005-2007 年期间，巴基斯坦和阿富汗持续存在野生 1 型脊灰病毒传播。序列数据提供的流行病学信息可以为制定更好的脊髓灰质炎控制策略提供依据，这些策略针对与高危人群有关的关键地区，这些人群包括移民、国内流离失所者和难民。这项研究的意义在于维持高质量的口服脊髓灰质炎疫苗（OPV）大规模免疫，以阻断两国的病毒传播链，推动东地中海区域取得实质性进展。
