Analysis of proteins, helper dependence, and seroepidemiology of a new human parvovirus

A new type of defective parvovirus, tentatively designated as adeno-associated virus type 5 (AAV-5), is characterized as far as its proteins, its helper dependence, and its seroepidemiology are concerned. The protein analysis of AAV-5 in polyacrylamide gels demonstrated the presence of three structural polypeptides, corresponding to VP 1, VP 2, and VP 3 of other AAV types. The preparation of monoclonal antibodies against AAV-5 permitted the analysis of viral structural antigen expression by using adenovirus type 12 (Ad 12) or several herpes group viruses as helper viruses, respectively. AAV-5-infected cell cultures coinfected with either Ad 12, Herpes simplex virus (HSV), Cytomegalovirus (CMV), or Varicella Zoster virus (VZV) efficiently synthesize AAV-5 specific antigens. Epstein-Barr virus (EBV) and Herpesvirus saimiri, in contrast, provide only a very weak helper activity for AAV 5 antigen expression. The development of a specific ELISA test permitted screening of human sera for antibodies to AAV-5. Forty-five percent of 926 sera from all age groups and approximately 60% of the adult population reveal antibodies to structural components of this virus. The seroepidemiology differs from that reported for other AAV serotypes. Highest average titers against AAV-5 are observed in the age group between 15 and 20 years. Sera from patients with cervical carcinoma revealed average titers of antibodies well below those of age-matched control groups. Attempts to find higher antibody levels against AAV-5 in specific human diseases failed thus far.