Epitope mapping of human herpesvirus-7 gp65 using monoclonal antibodies

Human herpesvirus (HHV)-7 encodes a unique 65-kDa heparin-binding glycoprotein, designated gp65. This molecule is thought to play a role in virus attachment and entry. To obtain reagents to map the structure and function of HHV-7 gp65, we produced monoclonal antibodies to this molecule. Ten monoclonal antibodies reacting with gp65 on ELISA were subdivided in four groups on the basis of their isotype and differential reactivity with (i) native versus denatured forms of gp65, and (ii) mature (virion-associated) versus immature (cell-associated) forms of the molecule. We were able to map the binding epitopes for eight of these ten antibodies, and these were found to cluster to one site on gp65 (amino acids 239-278); within this region, the antibodies reacted with at least three distinct domains (244-251, 255-262, 263-278). The reasons for the apparent immunodominance of this region are uncertain. Taken together, this panel of antibodies constitutes an extensive and well-characterized set of HHV-7 specific antibodies that may have utility for future analyses of the structure/function of gp65, and for studies on the virus life cycle.

Use of PCR in detection of Mycobacterium avium complex (MAC) bacteremia: sensitivity of the assay and effect of treatment for MAC infection on concentrations of human immunodeficiency virus in plasma

We evaluated the sensitivity and specificity of a PCR-based qualitative test for the rapid diagnosis of Mycobacterium avium-M. intracellulare complex (MAC) bacteremia in patients with AIDS disease. Eleven subjects with newly culture-proven MAC bacteremia had the following tests performed at biweekly intervals during the first 8 weeks of therapy: blood culture, Mycobacterium-specific PCR, and quantitative human immunodeficiency virus (HIV) viral-load testing. Mycobacterium genus-specific biotinylated primers were used to amplify a sequence of approximately 582 nucleotides within the 16S rRNA genes of M. avium and M. intracellulare. Detection of the amplified product was performed with an oligonucleotide probe-coated microwell plate combined with an avidin-horseradish peroxidase-tetramethylbenzidine conjugate-substrate system. While not as sensitive as BACTEC culture, PCR detected 17 of 18 specimens which grew >/=40 organisms/ml (94.4% sensitivity) and 9 of 16 specimens which grew </=40 organisms/ml (56.3% sensitivity). No clear change in HIV viremia occurred in response to successful treatment of patients' MAC bacteremia. Use of the PCR test allowed detection of MAC bacteremia in 1 day, with a sensitivity similar to those of quantitative blood culture techniques, and it may prove useful for rapid screening of suspected cases. HIV viremia was unaffected by 8 weeks of MAC therapy.