Genetic analysis of wild polioviruses and its ecology

Po1ioVirus是一种典型的肠道病毒，通过粪便经口传播给人类，人类是唯一敏感的动物。如果卫生条件良好，一旦存档并保持，就能防止脊髓灰质炎的大爆发。然而，为了根除这种疾病，社区一级--通过口服疫苗进行广泛免疫和实时临床--和病毒学监测是必不可少的。世界卫生组织于1988年启动了全球根除计划。在这项研究中，我们对印度支那地区被口服疫苗病毒取代的野生脊髓灰质炎病毒进行了基因分析。1997年，从越南1例急性弛缓性麻痹(AFP)患者和柬埔寨8例AFP患者中分离到野生型脊髓灰质炎病毒。他们都是I型脊髓灰质炎病毒。他们都在当地被诊断为AFP病例，他们的粪便样本被送往日本。我们分离了病毒，鉴定并进行了型内分化。测定了它们的VP1区核苷酸序列，并与该地区以前分离的野毒进行了比较。前些年在该地区分离到了几株不同的脊灰病毒。然而，1997年分离的9株毒株属于同一群毒株。从北越分离的脊髓灰质炎病毒都是疫苗衍生的病毒，而且在这三年里它们的数量有所减少。这些结果在日本得到了证实。相比之下，在南越和日本得到的结果有一些不同。利用表达脊髓灰质炎受体基因的小鼠La细胞，有效和选择性地分离到脊髓灰质炎病毒。该地区最后一例由野生脊髓灰质炎病毒引起的脊髓灰质炎病例被认为是1997年3月19日发现的一例。从那时起，没有分离到野生脊髓灰质炎病毒。有必要进行更广泛的监测，以证明无脊髓灰质炎。

Po1iovirus is a typical enterovirus and transmits from humans to humans by fecal oral routes Human being is the only sensitive animal. If good sanitary condition is once archived and maintained big outbreak of poliomyelitis wl11 be protected. However, in order to eradicate the disease poliomyelitis, community level-extensive immunity by oral vaccination and real time clinical-and viorological surveillance are essential. World Health 0rganization launched the global eradication program in 1988.In this study, we performed the genetic analysis of the wild polioviruses which has been replaced by oral vaccine viruses in Indochina area. In l997, wild type polioviruses were isolated from one patient with acute flaccid paralysis (AFP) from Vietnam and 8 from Cambodia. They were all type I poliovirus. They were all diagnosed locally as AFP cases and their stool samples were sent to Japan. We isolated viruses, identified add performed intratypic differentation. The nucleotide sequences of their VP1 region were determined and compared with those of wild viruses previously isolated in this area.In previous years, there were several different strains of wi1d polioviruses were isolated in this region. However, the 9 strains isolated in 1997 belonged to the same group of strain. From the North Vietnam, isolated polioviruses were all vaccine derived viruses, and their number has been decreased in these three years. Those results were confirmed in Japan. In contrast, there were some discrepancy in the results obtained in South Vietnam and Japan. By the use of mouse La cells expressing polio receptor gene, polioviruses were efficiently and selectively isolated.The last case of poliomyelitis by wild poliovirus in the region is so far considered to be the one found on March l9,1997. Since then, no wild polioviruses were isolated. More extensive surveillance is necessary to certify as polio-free.