Study of a novel picornavirus genus associated with Acute Flaccid Paralysis

描述(申请人提供)：仅在2008年，已开展脊髓灰质炎病毒监测方案的国家报告了85,400例急性弛缓性麻痹(AFP)病例，其中不到1,731例(2.03%)被发现与脊髓灰质炎病毒感染有关。利用元基因组学方法，我们在患有非脊髓灰质炎AFP的儿童中发现了一组高度分化的小核糖核酸病毒。对6种新病毒的全基因组进行了测序，系统发育分析表明，它们与所有已知的小核糖核酸病毒有很大的差异，形成了小核糖核病毒科的一个新属。为了开始测试这些名为人类CosaVirus(HCoSV)的新病毒是否是与非脊髓灰质炎AFP相关的重要病原体，我们使用特定的PCR引物对160例非脊髓灰质炎AFP病例的粪便样本进行了检测。107例AFP患者粪便标本中检出HCoSV RNA。多发性AFP患儿粪便标本中HCoSV变异体的高流行率和高病毒载量使我们推测HCoSV是一种与儿童AFP相关的人类病原体。对HCoSV变异株的初步系统发育分析表明，在这一新的皮科导航病毒科中存在四种不同的病毒种类。CosaVirus属各种间的遗传分化水平与肠道病毒属各种间的遗传分化水平相似。现在需要关于HCoSV遗传多样性和流行病学的进一步信息，以澄清其在AFP中的致病作用，如果得到证实，则用于制定预防其传播和疾病的战略。目的1确定大量AFP病例和人口学匹配的健康对照样本中不同HCoSV基因型的患病率，以检验是否与AFP显著相关，然后对最具差异性的HCoSV变异进行全基因组遗传学特征分析。目的2是利用细胞培养产生的病毒粒子或杆状病毒/昆虫细胞表达的病毒衣壳建立HCoSV的血清学检测方法。目的3将确定AFP病例、健康对照和普通人群中HCoSV血清反应性的流行率。因此，对一种新的人类微小核糖核酸病毒属的探索性研究将为可能的步骤提供基础，以减轻婴儿麻痹疾病造成的仍然很高的健康负担。我们最近在发展中国家对这种新的人类微小核糖核酸病毒属进行了表征和检测。我们的长期目标是确定HCoSV的致病潜力并防止新的感染。 与公共卫生相关：尽管脊髓灰质炎病毒已接近根除，但其他病毒引起的急性迟缓性麻痹仍经常给儿童造成严重的、有时甚至是永久性的损害，特别是在卫生条件差的发展中国家。在其余一半以上的非脊髓灰质炎急性迟缓性麻痹病例中，没有发现病毒。我们已经确定了在近一半接受测试的非脊髓灰质炎急性迟缓性麻痹病例中存在一个新的病毒群。我们希望对这种病毒的致病能力进行进一步的测试，并建立检测方法来衡量这种感染在普通人群中的普遍程度。如果拟议的研究确认这种新病毒是一种重要的病原体，它将为未来的干预措施提供基础，以防止其传播并减轻婴儿急性迟缓性麻痹的负担。

DESCRIPTION (provided by applicant): In 2008 alone, 85,400 cases of acute flaccid paralysis (AFP) were reported from the countries with active poliovirus surveillance programs, of which less than 1,731 (2.03%) were found to be associated with poliovirus infection. Using a metagenomic approach we have discovered a group of highly divergent picornaviruses in children suffering from non-polio AFP. The complete genomes of six new viruses were sequenced and phylogenetic analysis indicated them to be sufficiently divergent from all currently known picornaviruses to form a new genus in the Picornaviridae family. In order to begin testing whether these new viruses, named Human Cosavirus (HCoSV), were a significant pathogen associated with non-polio AFP we tested stool samples from 160 non-polio AFP cases using specific PCR primers. HCoSV RNA was detected in stool samples of 107 AFP cases. High prevalence and high viral load of HCoSV variants in stool samples of multiple AFP children leads us to hypothesize that HCoSV is a human pathogen associated with AFP in children. Initial phylogenetic analysis of HCoSV variants showed the existence of four different viral species within this new Picornaviridae genus. The level of genetic divergence between species of genus Cosavirus was similar to that between species of genus Enterovirus. Further information regarding HCoSV genetic diversity and epidemiology is now required to clarify its pathogenic role in AFP and, if confirmed, for developing strategies to prevent its transmission and disease. AIM 1 will determine the prevalence of different HCoSV genotypes in samples from a larger number of AFP cases plus demographically matched healthy controls to test whether there is a significant association with AFP, followed by full genome genetic characterization of the most divergent HCoSV variants. AIM 2 will be the development of a serological assay for HCoSV using virions produced by cell culture or viral capsids derived from baculovirus/insect cell expression. AIM 3 will determine the prevalence of seroreactivity to HCoSV in AFP cases, in healthy controls and in the general population. This exploratory study of a new human picornavirus genus that we have recently characterized and detected at high frequency in developing countries will therefore provide the foundation for possible steps to relieve the still high health burden imposed by infantile paralytic diseases. Our long-term goal is to define the pathogenic potential of HCoSV and to prevent new infections. PUBLIC HEALTH RELEVANCE: Despite the near eradication of poliovirus, acute flaccid paralysis caused by other viruses still inflicts frequent, severe, and at time permanent damages to children, particularly in developing countries with poor sanitation. No viruses have been identified for over half of the remaining cases of non-polio acute flaccid paralysis. We have identified a new viral group present in nearly half of the non-polio cases of acute flaccid paralysis tested. We wish to perform further tests of this virus' ability to cause disease and establish assays to measure how common this infection is in the general population. If the proposed study confirms this new virus as a significant pathogen it will provide the groundwork for future interventions to prevent its transmission and decrease the burden of infantile acute flaccid paralysis.