Presence of Human Bocavirus 1 and other Respiratory Viruses in Children with Lower Respiratory Tract Infection in Latvia

Lower respiratory tract infection (LRTI) is the major cause of morbidity and mortality of children in the world. In addition to respiratory syncytial virus, influenza virus types A and B, parainfluenza types 1, 2 and 3, and adenoviruses, several new respiratory viruses associated with LRTI were discovered in the 21^st century. These are metapneumovirus, coronaviruses NL63 and HKU1, parainfluenza virus type four and human bocavirus one (HBoV1). HBoV1 was discovered in 2005 and is considered as the fourth most prevalent respiratory virus worldwide. However, the high frequency of co-infections detected together with HBoV1 raises doubt about whether HBoV1 is a true pathogen or just a bystander. This is the first study aimed to determine the presence of HBoV1 and 18 other respiratory viruses in nasopharyngeal aspirates (NPA) of children with LRTI in Latvia. Using multiplex real-time polymerase chain reaction method, the HBoV1 genomic sequence was detected in 60.0% of NPA samples, showing that HBoV1 prevalence is high among children with LRTI in Latvia. HBoV1 mono-infection was revealed in 6.67%. The most common co-infections associated with HBoV1 were rhinovirus, adenovirus, respiratory syncytial virus A and B, metapneumovirus, and enterovirus.