Human Bocavirus: Developing Evidence for Pathogenicity

Abstract

number of individuals without respiratory symptoms were included as controls, and HBoV either was not found or was found very infrequently in this group of individuals. As described in both of these articles, HBoV is a member of the genus Bocavirus and is closely related to parvovirus B19, which also is in thesubfamilyParvovirinae in the family Parvoviridae. Thereareother bocaviruses found in cattle and in dogs; the name“bocavirus”itselfisderivedfrom the combination of “bo” (from “bovine”) and “ca” (from “canine”). One of these bocaviruses, bovine parvovirus, primarily causes diarrhea, and the other, minute virus of canines, causes neonatal respiratory disease and embryopathy. The human virus appears to be very common. In the 9 published studies of HBoV, the virus was detected in 1.5%–11.3% of individuals with acute respiratory illness who had respiratory samples screenedforHBoV,with a frequency of detection of 5.0%–5.5% noted for most of the studies [1–9]. All of the studies but one [5] have found that the virus is most frequently detected in infants !3 years of age. This frequency of detection makes HBoV less common than respiratory syncytial virus and probably also rhinoviruses in infants with respiratory illnesses; approximately as common as influenz viruses, human metapneumovirus, parainfluenz virus type 3, and adenoviruses; and probably more common than coronaviruses and the other parainfluenz viruses. What else do we know about HBoV? The answer is not much yet, even though the genome has been fully sequenced. The firs question we should ask aboutanymicroorganism that is found in the respiratorytractduringillnessiswhetheritcauses any disease. Could it simply be carried asymptomatically in the respiratory tract like, for example, the adenovirus-associated viruses, which are also members of the Parvoviridae family? Finding, in 2 studies, a zero or very low incidence among control infants of the same age, sampled over the same time period in the same hospitals, is a huge advance in this regard, because it provides a statistical association of the virus with disease. It does not, however, prove causality, although it adds important corroborative support.