Rapid detection of influenza virus infections in human fetal lung diploid cell cultures.

Haemadsorbing foci were found in human fetal lung (HFL) diploid cell cultures 12 h after inoculation with influenza viruses A and B. The size and number of the foci were maximal after 48 h of incubation, being limited by production of an unidentified inhibitor. By contrast, inoculation with parainfluenza virus type 3 led to haemadsorption which increased during 10 days of incubation. For the detection of influenza viruses A and B maximum sensitivity was achieved by changing the medium, the day before use to one that was serum free. The number of foci at 15.5 h post-infection and infectivity for primary African green monkey kidney (AGMK) cultures were similar. Virus infectivity and production of haemagglutinin in HFL cells were entirely cell-associated; they were not affected by treatment with trypsin. Nevertheless, influenza viruses A and B antigens were identified in the infected cells by means of immunofluorescence at 15.5 h and virus was recovered by passage of frozen and thawed cells in AGMK cultures. For rapid routine diagnosis of viral infections, the early haemadsorption test was shown to have the same sensitivity as immunofluorescence tests on specimens and virus detection by the shell-vial technique but was cheaper and simpler to perform.

Mycoplasma pneumoniae infections in a rural setting in Canada.

Mycoplasma pneumoniae infection was monitored in patients with symptoms of acute respiratory tract infection in a village in southeastern Ontario from April 1983 to April 1984. M. pneumoniae was isolated from 51 (48%) of the 106 patients. The incidence began to increase in May 1983, reached a peak in July and declined to normal by mid-August. During the epidemic period M. pneumoniae was detected in 36 of the 43 symptomatic patients. The most prominent features of the outbreak were the considerable intrafamilial attack rate and the high frequency of pneumonia among infected patients. Treatment with tetracyclines and erythromycin reduced the duration of the illness and accelerated the resolution of symptoms.

Sensitivity and specificity of enzyme immunofiltration and DNA hybridization for the detection of HCMV-infected cells.

The sensitivity and specificity of enzyme immunofiltration and DNA hybridization were compared in human cytomegalovirus (HCMV) (AD 169)-infected MRC-5 cells. The enzyme immunofiltration was carried out on glass fiber filters in microplates, using an HCMV (AD 169) monoclonal antibody and a peroxidase conjugate. The DNA hybridization was carried out with a microfiltration apparatus, using a 32P-labelled HCMV (AD 169) Eco R1 D fragment probe. The sensitivities of enzyme immunofiltration and DNA hybridization were 1.82 X 10(3) and 1.13 X 10(3) infected cells, respectively. Both methods were highly specific, but enzyme immunofiltration was faster and simpler.

Reduction of nonspecific fluorescence in respiratory specimens by pretreatment with N-acetylcysteine.

Treatment of nasopharyngeal specimens with 0.25% N-acetylcysteine for 20 min at room temperature effectively reduced the nonspecific fluorescence encountered during direct examination of the specimens by immunofluorescence. The treatment did not affect specific antigen staining or the viability of several common respiratory viruses.

Microcarriers in combination with enzyme immunofiltration and immunofluroescence for the detection of herpes simplex virus antigens in culture.

A microcarrier culture system in combination with enzyme immunofiltration with a herpes simplex virus (HSV) group monoclonal antibody was found to be as sensitive as immunofluorescence for the detection of HSV type 1 (HSV-1) in cell cultures and to give specific identification at the same time as the appearance of the cytopathic effect with very high infectious inocula and within 10 to 24 h of the appearance of the cytopathic effect with very high infectious inocula and within 10 to 24 h of the appearance of the cytopathic effect with low to high inocula. Multiplicities of infection from 10(-5) to 10(1) were tested at 8 to 96 h postinfection. When applied to the identification of HSV-1 and HSV-2 in cultures of clinical samples, the system detected HSV antigens in 50% of the samples after 2 days and in 100% of the samples after 3 days. With 2 ml of microcarrier suspension and with 50 to 300 microliter per sample, several portions are available for replicate and sequential sampling without destroying the culture. The system requires only that 2 X 10(5) microcarriers be added to the culture tube at the time or before it is seeded with cells, at an extra cost of 6 cents (U.S.) per tube and little extra labor.

Comparison of five methods of cytomegalovirus antibody screening of blood donors.

A group of 120 sera from blood donors was screened by complement fixation and commercially available immunofluorescence, solid-phase fluorescence immunoassay, enzyme-linked immunosorbent assay, and indirect hemagglutination tests. Twenty-four of the sera were positive by three or more of the five tests and judged to be true positives; 89 were negative by three or more of the tests and considered to be true negatives. The tests were ranked for accuracy, sensitivity, specificity, false-positive rate, and false-negative rate. The indirect hemagglutination test scored best, followed by enzyme-linked immunosorbent assay, solid-phase fluorescence immunoassay, complement fixation, and immunofluorescence, in that order. When the tests were ranked on the basis of technical demands, turnaround time, requirement for special equipment, and subjectivity in reading, the indirect hemagglutination test again scored best, followed by solid-phase fluorescence immunoassay, enzyme-linked immunosorbent assay, immunofluorescence, and complement fixation in that order. Our findings suggest that the indirect hemagglutination test is the most reliable and effective commercially available test for the identification of those donors who are very unlikely to transmit cytomegalovirus to recipients.

Persistence of naturally acquired cell-mediated immunity to rubella virus during the first trimester of pregnancy.

We studied the persistence of naturally acquired cell-mediated immunity to rubella during early pregnancy. We compared lymphocyte transformation responses to phytohemagglutinin and rubella virus in 35 naturally immune women aged 17-37 years, in the first trimester of pregnancy, with 49 naturally immune age-matched nonpregnant controls. A significant lower lymphocyte transformation response to phytohemagglutinin was observed during the first trimester of pregnancy (P = 0.008), but lymphocyte transformation responses to rubella virus were not significantly different (P = 0.901). These data indicate that, in naturally immune women, cell-mediated immunity to rubella virus is not significantly altered by the physiological changes in early pregnancy.

Persistence of humoral and cell-mediated immunity to rubella virus in cloistered nuns and in schoolteachers.

Humoral and cell-mediated immunity to rubella virus after naturally acquired infection were compared in 19 cloistered nuns (29-79 years of age), 18 female schoolteachers (21-61 years of age), and 21 female control subjects (20-30 years of age), who were all seropositive for rubella virus, by use of a hemagglutination-inhibition test, a passive hemagglutination test, a hemolysis-in-gel test, a radioimmunoassay, an enzyme-linked immunosorbent assay, and lymphocyte transformation tests. No significant differences were found among the groups by the radioimmunoassay, the hemolysis-in-gel test, and the enzyme-linked immunosorbent assay. The cloistered nuns had significantly lower cell-mediated immunity to rubella virus than did the teachers and the control subjects but nonetheless showed protective levels of antibody to rubella virus and significant lymphocyte transformation responses, which persisted until age 79 in the probable absence of reinfection.

The relative ability of four rubella antigens to elicit blast cell transformation of lymphocytes from immune individuals.

The ability of crude, semi-purified, and purified rubella antigens to elicit a specific and significant blast cell transformation of lymphocytes from immune individuals was investigated in 25 seronegative and 25 seropositive young adults. The type of preparation and the purity of the antigens were critical. Titration of the antigens by complement fixation or hemagglutination was of little value for selecting the best antigen which was a whole virion-purified antigen.

Absence of cell-mediated immunity to rubella virus 5 years after rubella vaccination.

The long-term effectiveness of rubella vaccination in childhood is particularly important because the ultimate goal of immunization is the prevention of infection during pregnancy. Of 25 healthy children tested 4 to 5 years after rubella vaccination, 19 showed no evidence of cell-mediated immunity (CM) to rubella virus despite the presence of hemagglutination-inhibition or complement-fixation antibodies or both. Twenty-two of 25 seropositive, naturally infected young adults showed evidence of CMI. These results indicate that fetuses of women who have been vaccinated against rubella may not be protected against damage by wild rubella infection during the pregnancy, when CMI is physiologically depressed.