Characterization of Acute-Phase Humoral Immunity to Monkeypox: Use of Immunoglobulin M Enzyme-Linked Immunosorbent Assay for Detection of Monkeypox Infection during the 2003 North American Outbreak

Retrospective Analysis of Monkeypox Infection

“…If these contacts contracted monkeypox infections, then this would contradict our previous fi ndings in which unvaccinated monkeypox patients showed at least some, if not all, disease symptoms associated with monkeypox (6,8). It is diffi cult to directly compare our results with these other reports (10,29) because different subsets of monkeypox patients were examined, different time points were analyzed, and different case defi nitions were used. For instance, the CDC case defi nition is based on a combination of clinical, Figure 3.…”

“…An IgM capture ELISA for diagnosing monkeypox (29) was developed by using vaccinia virus as a surrogate antigen for monkeypox, and the investigators reported 100% specifi city and 92% sensitivity. Per CDC monkeypox case defi nition, these cases had been confi rmed by direct viral detection including PCR, electron microscopy, virus isolation, or immunohistochemistry.…”

“…Historically, several serologic techniques have been used to identify orthopoxvirus infections, including hemagglutination-inhibition (13), gel precipitation (17,22,23), complement fi xation (22), cross-neutralization (14), immunofl uorescence (24,25), Western blot (26,27), radioimmunoassay (13,15), and ELISA (28,29). In previous studies, we used a peptide-based ELISA with peptide sequences from the monkeypox B21R gene to differentially diagnose monkeypox infection (6).…”

Evaluation of smallpox vaccines using variola neutralization

“…All four experimentalists performing PRNTs obtained 60 % VAR PRNT titres at a 1 : 16 000 end point with VIG, and 90 % VAR PRNT titres at a 1 : 2000 end point with VIG. Two negative-control sera were used (Karem et al, 2005). With one negative-control serum, three of three experimentalists performing PRNTs obtained 60 % PRNT titres at a 1 : 20 end point and 90 % PRNT titres at a ,1 : 10 dilution end point.…”

“…Mock serum dilutions were used to quantify the 'virus-only' control. Positive (sera from previously vaccinated persons) and negative (Davies et al, 2007;Karem et al, 2005) serum controls were used to validate the assay. Vaccinia immune globulin (VIG), used as one of the positive controls, was used at dilutions of 1 : 1000-1 : 32 000 based on prior knowledge of vaccinia-neutralizing capacity.…”