Production of human parvovirus 4 VP2 virus-like particles in yeast and their evaluation as an antigen for detection of virus-specific antibodies in human serum.

BACKGROUND: Human parvovirus 4 (PARV4) is a recently discovered member of the Parvoviridae family, which is not closely related to any previously discovered human parvoviruses. PARV4 has been isolated from the plasma of individuals with symptoms of acute viral infection; however, until recently PARV4 had not been associated with any disease, and its prevalence in the human population is yet to be established. METHODS: The major capsid protein VP2 of PARV4 was generated in the yeast Saccharomyces cerevisiae and used for serological detection of virus-specific IgG and IgM in the sera of low-risk individuals. RESULTS: One hundred and seventy serum specimens obtained from patients with acute respiratory diseases were tested for PARV4-specific IgG and IgM antibodies. Sixteen individuals (9.4%) were diagnosed as seropositive, including 6 IgM and IgG positive, 6 IgM positive/IgG negative and 4 IgG positive/IgM negative. Seven of the 16 seropositive individuals were between the ages of 3 and 11 with no evidence of parenteral exposure to PARV4 infection. CONCLUSION: Our data demonstrate that recombinant yeast-derived VP2 protein, self-assembled to virus-like particles, can represent a useful tool when studying the seroprevalence of PARV4 infection. The presence of PARV4-specific antibodies in a low-risk group may indicate the possibility of alternative routes of virus transmission.

T cell and eosinophil activation in mild and moderate atopic and nonatopic children's asthma in remission.

BACKGROUND: Inflammation in the pathogenesis of asthma is associated with products of activated T cells and eosinophils. The aim of this study was to determine whether ongoing inflammation persists in children with different phenotypes of asthma despite the disease in remission. METHODS: Serum samples were collected from 68 children with atopic or nonatopic asthma in remission and from 15 healthy children. Soluble interleukin-2 receptor (sIL-2R), IL-2 and IL-4 were examined by using an enzyme-linked immunosorbent assay. Total and specific immunoglobulin E, and eosinophil cationic protein (ECP) were analysed by fluoroimmunoassay (Pharmacia CAP System). RESULTS: In patients with moderate persistent atopic asthma, sIL-2R was increased significantly when compared with mild persistent atopic asthma (P < 0.05). No changes of sIL-2R were seen in nonatopic asthmatics compared with atopics and controls. The level of IL-2 was elevated in moderate persistent atopic and nonatopic asthmatic children compared with controls (P < 0.05 and P < 0.05 respectively) and compared with mild persistent atopic asthmatics and mild persistent nonatopic asthmatics (P < 0.05 in both cases). The levels of IL-4 in most patients and controls remained below the sensitivity of the assay. Eosinophil cationic protein levels in moderate persistent atopic and nonatopic asthmatics were significantly higher than in mild persistent asthma severity cases (P < 0.001 and P < 0.01 respectively) and in healthy children (P < 0.01 in both cases). CONCLUSION: Changes in the concentration of sIL-2R, IL-2 and ECP reflect increased T cell and eosinophil activity in relation to the level of severity of asthma in atopic and nonatopic children, thereby proving the presence of persistent inflammation despite the absence of disease symptoms.