Déjà vu all over again: Koch's postulates and virology in the 21st century.
Déjà vu all over again: Koch's postulates and virology in the 21st century.
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似曾相识的感觉再次出现：科赫的假设和 21 世纪的病毒学。
DOI：
10.1086/652406
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Williams,JohnV
中科院分区：
文献类型：
--
作者：
Williams,JohnV
In this issue of the Journal, Martin et al [1] report the results of a prospective longitudinal cohort study of acute respiratory illness in children who attended daycare. This article describes prolonged shedding of the recently identified human bocavirus (HBoV) by children and detection of HBoV in the absence of respiratory symptoms. Their findings argue against the hypothesis that HBoV is a primary respiratory pathogen, leaving the biological significance of HBoV infection in question. The work also nicely illustrates a common problem facing modern virologists: how to assign disease causality to a microorganism that is not amenable to Koch’s postulates. Molecular discovery techniques have identified numerous viruses that, like HBoV, have yet to be definitively established as pathogens. HBoV is a human parvovirus discovered in 2005 by Allander et al [2] with use of an elegant molecular virus-sequencing approach. Genomic analysis showed that HBoV was distinct from the other known human parvovirus B19 and was most closely related to bovine and canine parvoviruses (hence the genus name Bocavirus). HBoV was originally identified in specimens from children with acute respiratory illness, and therefore a putative association with respiratory disease was proposed. HBoV joined the ranks of several other recently discovered human viruses, including human metapneumovirus (HMPV) and human coronaviruses NL63 and HKU-1 [3–5]. Many groups that had published studies of HMPV and HCoV NL63 rapidly tested similar specimen collections for HBoV [6–9]. These initial studies and others have detected HBoV by polymerase chain reaction (PCR) in specimens from children with acute respiratory illness worldwide at frequencies of 5%–20%[10–15]. However, many of these studies were limited to convenience samples collected during routine clinical care in a variety of settings and, therefore, were subject to case ascertainment and illness severity bias, and most of these studies lacked appropriate controls. Furthermore, other viruses present in the specimens were frequently detected by less sensitive methods, such as direct immunofluorescence and culture, making determination of coinfection rates difficult. The present study sought to address the limitations of some previous work. Martin et al [1] recruited 119 previously healthy children 6 weeks through 24 months of age (mean age, 10 months) at 3 daycare centers on a large military base and observed the cohort for a mean follow-up period of 1 year (range, 11 days through 2 years). Flocked nasal swab samples were collected at enrollment and with each new acute respiratory illness; additional swab samples were obtained weekly during clinical respiratory episodes. Parents, daycare staff, or active surveillance by an onsite study nurse identified new illnesses. HBoV and, importantly, other respiratory viruses were detected by PCR. HBoV was detected in 106 (33%) of 318 episodes of acute respiratory illness during the study; in 72% of these episodes, other viruses were detected in addition to HBoV. This high rate of co-detection of other viruses in addition to HBoV is in agreement with other reports of 60%–90% co-detection when other viruses were analyzed by molecular methods [13, 16–23]. This raises a challenge in assigning causality to HBoV as a sole primary respiratory pathogen: the majority of HBoV-infected children with acute respiratory illness are also infected with viruses that are established causes of such illnesses.
