Our aim was to estimate the presence of B19V infection markers, the level of cytokines and time period since the appearance of infection in association with ME/CFS clinical symptoms. In 200 ME/CFS patients and 104 control group individuals the presence of B19V-specific IgG/IgM class antibodies, B19V NS1 gene sequence, mRNA expression, viral load and level of cytokines were determined. B19V-specific IgG-antibodies were found in 70% of ME/CFS patients and 67.4% of controls, IgM-antibodies in 8% of patients and in none of controls, B19V genomic sequences in 29% of patients and 3.8% of controls. 58.6% of positive patients had active and 41.4% had latent/persistent B19V infection. B19V NS1 gene expression was detected in 43% of patients. B19V load varied from < 0.2 copies to median 38.2 copies/µg of DNA. According to the antibody pattern, 36% of patients had a recent, and 43% had sustained B19V infection. Patients with the B19V genomic sequence and NS1 specific antibodies significantly more often had lymphadenopathy and multi-joint pain. Onset of the symptoms corresponded to time of appearance of B19V infection. IL-10 and TNF-levels were higher in patients with elevated B19V load. B19V genome 1 was identified in Latvian ME/CFS patients. The results indicated that at least in some cases B19V infection plays an important role in ME/CFS development
Since its discovery in 2005, human bocavirus 1 (HBoV1) has globally been one of the most common respiratory viruses. It is currently accepted that HBoV1 is a pathogen, causing upper and lower respiratory tract infections (LRTIs) in children. However, due to the prolonged HBoV1 DNA shedding from the upper airways and the subsequent high rate of co-detections with other respiratory viruses, the interpretation of positive polymerase chain reaction results is challenging. The aim of this study was to identify acute HBoV1 infections by the presence of HBoV1-specific IgM and IgG measured by competition enzyme immunoassay, to elucidate the induction of Th1/Th2 cytokines, and to describe the clinical characteristics associated with acute HBoV1 infection in hospitalised children less than five years of age with LRTI. HBoV1 IgM was detected in 19/102 (18.6%) and IgG in 66/102 (64.7%) patients. HBoV1 IgM was most frequently found in patients aged 13 to 24 months. Pneumonia and acute wheezing were the most common clinical diagnoses among HBoV1 IgM positive patients. The seroprevalence of HBoV1-specific IgG increased with age, reaching 85% by the age of five years. INF-γ, IL-4, IL-5, and IL-10 were observed to be higher in patients with acute HBoV1 infection.