Human bocavirus (HBoV) is a new parvovirus associated with acute respiratory tract infection (ARTI). In order to evaluate HBoV significance as an agent of acute respiratory disease, we screened 1,135 respiratory samples from children and adults with and without symptoms during two complete calendar years. HBoV1 prevalence in patients with ARTI was 6.33 % in 2011 and 11.64 % in 2012, including neonatal and adult patients. HBoV1 was also detected in 3.77 % of asymptomatic individuals. The co-detection rate was 78.1 %. Among children, 87 % were clinically diagnosed with lower respiratory infection (no significant differences between patients with and without coinfection), and 31 % exhibited comorbidities. Pediatric patients with comorbidities were significantly older than patients without comorbidities. Patients with ARTI had either high or low viral load, while controls had only low viral load, but there were no clinical differences between patients with high or low viral load. In conclusion, we present evidence of the pathogenic potential of HBoV1 in young children with ARTI. Since patients with HBoV1-single infection are not significantly different from those with coinfection with respect to clinical features, the virus can be as pathogenic by itself as other respiratory agents are. Furthermore, an association between high HBoV1 load and disease could not be demonstrated in this study, but all asymptomatic individuals had low viral loads. Also, children with comorbidities are susceptible to HBoV1 infection at older ages than previously healthy children. Thus, the clinical presentation of infection may occur depending on both viral load and the particular interaction between the HBoV1 and the host.

Instituto de Virología 'Dr J. M. Vanella', Facultad de Ciencias Mé dicas, Universidad Nacional de Có rdoba, ArgentinaHuman bocavirus (HBoV) is a parvovirus with a possible aetiological role in respiratory disease that is currently under investigation. We detected HBoV1 in children and adults hospitalized with acute disease of the lower respiratory tract. HBoV genome was detected by PCR in nasopharyngeal swabs collected from 75 patients aged 0-89 years during 2010. HBoV was found in 17/75 (22.7 %) patients, 64.7 % of them infants younger than 1 year old and 29.4 % adults older than 30 years [the bimodal age distribution among HBoV-positive (HBoV + ) patients was statistically significant, P,0.001]. Of all HBoV + cases, 35.3 % were co-infected; all coinfections occurred in children (¡13 years old) and 83.3 % of them were HBoV-respiratory syncytial virus (RSV) co-infections. Among infants younger than 1 year, 50 % HBoV + specimens were co-infected, all of them with RSV. The rate of co-infection in infants was significantly higher compared to the frequency of co-infection in the whole cohort (P50.003). The results suggest that HBoV1 is involved in acute respiratory disease. Interplay between HBoV1 and RSV cannot be discarded as a cause of elevated percentages of co-detections in infants. INTRODUCTIONHuman bocavirus (HBoV) is a parvovirus first identified in 2005 in nasopharyngeal aspirates of children with lower respiratory tract infection (Allander et al., 2005). Since then, it has been associated with upper and lower acute respiratory infection (ARI), a leading cause of acute illnesses worldwide and the most important cause of mortality in infants and young children and disabilityadjusted life-years lost in developing countries (Simoes et al., 2006; WHO, 2009). To date, four species of HBoV have been proposed, and the name human bocavirus 1 (HBoV1) was suggested for the originally discovered virus. HBoV1 is linked to respiratory disease, while it is believed that HBoV2-4 are associated with gastroenteritis (Kapoor et al., 2010). With a ubiquitous distribution, the presence of HBoV DNA has been reported mostly in children with ARI in a variable range from 1.5 to 19 % (Allander, 2008), although recently even higher prevalence (33 %) has been observed in ill children (Martin et al., 2010). Although the virus is associated with ARI, the elevated rates of coinfection with other respiratory viruses with well-established pathogenic potential (Kaplan et al., 2006;Allander et al., 2007;Fry et al., 2007; Gerna et al., 2007;Kleines et al., 2007; Christensen et al., 2008 Christensen et al., , 2010Cilla et al., 2008;Pilger et al., 2011), the detection in asymptomatic individuals (Christensen et al., 2010) and the possibility of a persistent infection (Martin et al., 2010) make it difficult to allocate a causative role for HBoV in respiratory disease. Not only is the aetiological capacity of HBoV under investigation, but the natural history of the infection is still unknown. In addition, the impact of HBoV on the global epid...

A B S T R A C T Human bocavirus (HBoV) is a parvovirus whose association with respiratory disease is currently under investigation.Objective: To determine HBoV prevalence in children with lower acute respiratory infection. Results: The general prevalence of HBoV was 21.5% and the positive cases (HBoV+) were more frequent during winter and spring. The mean age of HBoV+ patients was 6.9 months, with 87.1% of the detections corresponding to infants less than 1 year old (among which the prevalence of HBoV was 26.3% in patients < 3 months of age, 22.1% in 3 to 6 months, 25.3% in 6 to 9 months, and 18.8% in 9 to 12 months). The sequence analysis of the NP1 coding region of 15 isolates showed that all isolates from Cordoba were HBoV1 which exhibited a homology of nearly 100% both among themselves and with the originally discovered virus from 2005. Conclusion:Overall, our results indicate that HBoV is a significant pathogen that contributes to acute respiratory infection both on its own and during coinfection with other viruses.

The contribution of parvovirus B19 (B19V) as a causative agent of febrile exanthema (FE) in Cordoba, Argentina, was analysed by detection of viral DNA, and specific IgM and IgG. Serum from 141 patients with FE who were negative for measles and rubella, collected during 2005-2009, plus serum from 31 healthy individuals, were assayed. B19V was the aetiological agent in 14·9% of all FE cases, and in 39·1% in an epidemic year (2007). B19V DNA was detected in 47·6% of IgM-positive FE patients, 30·2% of IgM-negative/IgG-positive FE patients, and 9·7% of healthy controls, indicating B19V long-term infection in ~10% of immunocompetent individuals. Persistent B19V DNA was significantly more frequent in children than adults and in males than females. All patients with acute B19V infection had rash and fever, 85·7% had adenopathy, and only 14·3% had arthropathy. This is the first follow-up study of markers of infection and immunity for B19V infection in Argentina.

Overall, our results indicate that HBoV is a significant pathogen that contributes to acute respiratory infection both on its own and during coinfection with other viruses.

Human bocavirus 1 (HBoV1) is a parvovirus associated with pneumonia in infants. It has been detected in different tissues, including colorectal tumors. In this study, we investigated whether Caco-2 cell line, derived from human colon cancer, can be utilized as a model for HBoV1 replication. We demonstrate HBoV1 replication in Caco-2 cultures supplemented with DEAE-dextran after inoculation with respiratory material from infected patients presenting with acute respiratory infection. A viral cycle of rapid development is displayed. However, in spite of HBoV1 DNA 4-fold increment in the supernatants and monolayers by day 1, evidencing that the system allows the virus genome replication after the entry occurred, infectious progeny particles were not produced. These results are consistent with an infection that is limited to a single growth cycle, which can be associated to mutations in the NS1 and VP1/VP2 regions of HBoV1 genome. Further research will contribute to fully elucidate these observations.

This is the first study of respiratory infections in Córdoba, Argentina, caused by endemic human coronavirus (HCoV)-OC43 and HCOV-229E, which circulated during 2011-2012 at a 3% rate, either as single or multiple infections. They were detected mainly in children, but HCoV-229E was also found in adults. HCoV-229E was detected in five out of 631 samples (0.8%), and HCoV-OC43 was found in 14 out of 631 (2.2%) samples. Clinical manifestations ranged from fever to respiratory distress, and a significant association of HCoV-229E with asthma was observed. Further studies and surveillance are needed to provide better clinical insights, early diagnosis, and medical care of patients, as well as to contribute to epidemiology modeling and prevention.

No abstract