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An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to toxins A and B of Clostridium difficile was developed. Serum samples from 340 patients were tested for determination of the age-related prevalence of antitoxin. Antibody to toxin A was present in 64% of patients more than two years old and antibody to toxin B in 66% of patients more than six months old. A strongly positive ELISA value correlated with the presence of cytotoxicity-neutralizing antibody (P < 0.001). Strongly positive ELISA values were obtained more commonly in convalescent sera from 16 patients with C difficite-induced colitis than in sera from the control population (antibody to toxin A, P < 0.05; antibody to toxin B, P < 0.001). Testing of paired sera revealed significant increases in the titer of IgG antibody to toxin A or B. Ten of the 16 patients with colitis had IgM titers of ⩾1:160 to one or both toxins. The data presented suggest that antibodies to toxins A and B are present in the majority of older children and adults and that patients with C difficile-induced disease develop serologic responses to one or both toxins. [ABSTRACT FROM PUBLISHER]

Background: A competitive Luminex Immunoassay (cLIA) has been developed to measure neutralizing antibodies against human papillomavirus (HPV) types 6, 11, 16 and 18., Methods: In a cohort of 974 women from the Guanacaste Natural History Study, we studied the relationship of baseline cLIA and virus-like particle (VLP) enzyme-linked immunosorbent assay (ELISA) (HPV16 and HPV18 only) seropositivity to measures of HPV exposure, HPV DNA positivity, number of sexual partners, cytology findings, and age. We then studied immunity against subsequent infection with HPV6, 11, 16, 18 and related types over a 7-year period., Results: cLIA seroprevalence varied with previous exposure; the prevalence of cLIA results positive for HPV16 and HPV18 was lower than the prevalence of positive VLP ELISA responses. cLIA and VLP ELISA positivity predicted protection from subsequent infections with concordant types. The combined odds ratio for HPV16 and HPV18 cLIA positivity was 0.41 (95% confidence interval [CI], 0.21-0.80), and the combined odds ratio for the HPV16 and HPV18 VLP ELISA positivity was 0.65 (95% CI, 0.46-0.93). Of individual types, statistical significance was only reached for HPV16 cLIA positivity (odds ratio, 0.44; 95% CI, 0.15-0.94)., Conclusions: Both assays showed an association between positive results and significant protection from subsequent infections for HPV16 and HPV18 combined. cLIA seroprevalence was lower than VLP ELISA, suggesting that the assay detects a subset of antibodies following natural infection that are specifically linked to immunity against subsequent HPV infection.

The prevalence and risk factors for oral human papillomavirus (HPV) infection are unknown, despite evidence for an etiological role for HPV in oral cancers. Oral samples from human immunodeficiency virus (HIV)-seronegative (n=396) and HIV-seropositive (n=190) adults were tested for HPV DNA. High-risk HPV infections were present in 2.1% of tonsil and 6.3% of oral-rinse specimens. The prevalence of oral high-risk HPV infection was greater in HIV-seropositive individuals (13.7% vs. 4.5%; P<.001). In multiple logistic regression, odds of oral HPV infection increased with age, male sex, and herpes simplex virus (HSV)-2 seropositivity in HIV-seronegative individuals and with CD4 cell count <200 cells/mL, HSV-2 seropositivity, oral mucosal abnormalities, and >1 oral sex partner during the previous year (odds ratio, 12.8; 95% confidence interval, 3.1-52.7) among HIV-seropositive individuals. HPV type 16, which is present in most HPV-associated tonsillar cancers, was the most prevalent high-risk oral HPV infection.