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A detailed investigation has been made of the pock-counting method for titrating vaccinia virus on embryonated eggs with a view to eliminating the wide scatter of results hitherto inseparable from the technique, and of assessing the precision of which it is capable. A detailed description is given of the technique evolved.Reasons are given for supposing that the distribution of counts should follow the Poisson series, and considerable progress is claimed towards the achievement of such a distribution.

One hundred and three patients (90 nonatopics and 13 atopics) with respiratory infections to various viral agents were studied retrospectively with respect to IgE immunoglobulin levels during acute (1 to 7 days) and convalescent (8 to 30 days) phases of infection. It was found that 59% of patients had a decrease of 20% or more in IgE level, 27% remained the same, and only 14% showed a rise 20% or more from the acute to the convalescent phases of infection. IgE levels decreased up to 3 to 4 wk after symptoms and the degree of decrease was more apparent for the nonatopics who had higher IgE levels in their acute phase of infection. Less dramatic decrease in IgE was observed for the 13 atopics studied. The changes in IgE levels during the viral infectious period are discussed in terms of possible cellular mechanisms that may control IgE immunoglobulin.

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, solidphase 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 solidphase 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.

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