Multicenter evaluation of a rapid and convenient method for determination of cytomegalovirus immunoglobulin G avidity.

An easy, rapid, and reproducible test to distinguish residual cytomegalovirus (CMV) immunoglobulin M (IgM) antibodies from antibodies produced in primary infection could be useful, especially for pregnant women. The CMV avidity of IgG antibodies with the VIDAS automated enzyme-linked fluorescent assay and 6 M urea was evaluated in a multicenter study to differentiate between primary CMV infections and past infections or reactivations. A total of 416 serum specimens were tested: 159 specimens were from follow-up of primary infections, and 257 were from past infections. All of the specimens from primary infections collected within 4 months (17 weeks) after the onset of the infection had an avidity index lower than 0.8. An avidity index higher than 0.8 excludes a recent primary infection of less than 4 months. However, an avidity index higher than 0.8 cannot confirm all past infections, since 48 specimens (18%) from past infections had an avidity index lower than 0.8 (between 0.5 and 0.8). The exclusion capacity could be improved (96.9%) by using a cutoff of 0.7, but this index would decrease the specificity of the technique, since the avidity index was found to be between 0.7 and 0.8 in two patients with recent primary infection. All specimens from primary infections obtained more than 4 months after the onset of infection had an avidity index more than 0.2. In this study, an avidity index less than 0.2 confirms the presence of a recent primary infection of less than 4 months. The VIDAS CMV IgG avidity test is a rapid, reproducible test with very good performance.

Fast solid support detection of human papillomavirus in in vitro amplified DNA using a DNP-anti DNP monoclonal antibody couple.

In some anogenital lesions the detection of certain types of human papilloma virus, especially oncogenic types, is of interest. In a first step during a prospective study, we compared two methods for the detection of human papillomavirus (HPV) DNA in clinical samples: Southern blotting followed by hybridization with a cloned radioactive genomic probe and a classical polymerase chain reaction (PCR) followed by hybridization with a 32P-labelled oligonucleotide probe. 118 biopsies and swabs were examined for HPV 6/11, 16, 18 and 33, 67 positive reactions were found by both methods, 5 positives only by PCR and 2 positives only by Southern blot for unidentified HPV. Patients with anogenital condylomas, dysplasias and carcinomas or asymptomatic patients were studied. Most high grade (II and III) dysplasias were associated with HPV 16 and HPV 18. Condylomata lesions and low grade dysplasia (grade I) were associated mostly with HPV 6/11, mixed type of HPV, less frequently with HPV 16 or HPV 18. As a second step a nested PCR coupled to solid support detection method was used as described by Sauvaigo et al. (1990) Nucleic Acids Res. 18, 3175-3183) to study a panel of 30 previously qualified different HPV DNA extracts. In this procedure the second round of PCR amplification involves biotinylated and dinitrophenylated labelled primers allowing the capture of PCR amplified HPV DNA sequences on streptavidin coated tubes and its revelation. We describe an improvement of HPV DNA detection by means of single-step immunoenzymatic revelation involving anti-DNP monoclonal antibodies conjugated to horseradish peroxidase enzyme. A perfect correlation with the previous results was obtained. This solid support method allows a faster and easier HPV typing compared to methods using membrane transfer.

Infantile gastroenteritis caused by rotavirus: comparison of enzyme-linked immunosorbent assay and electron microscopy for rapid diagnosis.

ELISA and negative contrast EM have used for the detection of rotavirus in one hundred stools from children, less than two years old, hospitalized for acute gastro-enteritis during the winter 1977-78. Samples obtained from the same children some months after hospitalization were also tested. A good correlation was found between the results given by EM and ELISA, but the later technique turned out to be more sensitive (12% more positive using ELISA). A rotavirus infection could be demonstrated in 73% of the patients. In the stools of 3 children we found a second virus in association with the rotavirus, and in two cases a pathogenic bacterium. When a second serum specimen was available from children previously infected by rotavirus it was always possible to detect a significant increase in CF antibodies. Several months after hospitalization a 2nd survey indicated that the rotavirus was no longer present but calicivirus, echovirus, coxsackievirus and adenovirus could be detected in those asymptomatic children.