Adeno-associated virus and development of cervical neoplasia

Evidence from several sources has suggested that adeno-associated virus (AAV) infection might protect against cervical cancer, in part, by interfering with human papillomavirus (HPV)-induced tumorigenesis. Detection of AAV type 2 (AAV-2) DNA in cervical tissues has been reported. However, there have been few in vivo studies of women with cervical HPV infection or neoplasia, and these have reported inconsistent results. Therefore, we used polymerase chain reaction (PCR) assays targeted to the AAV-2 rep and cap genes to test tissue specimens from women in an epidemiological study of cervical neoplasia in Jamaica. We tested 105 women with low-grade cervical intraepithelial neoplasia (CIN-1), 92 women with CIN-3/carcinoma in situ or invasive cancer (CIN-3/CA), and 94 normal subjects. PCR amplification of human beta-globin DNA was found in almost all cervical specimens, indicating that these materials were adequate for PCR testing. The prevalence of HPV DNA, determined by HPV L1 consensus primer PCR was, as expected, strongly associated with presence and grade of neoplasia. Each of the AAV PCR assays detected as few as 10 copies of the virus genome. However, none of the 291 cervical specimens from Jamaican subjects tested positive for AAV DNA. Negative AAV PCR results were also obtained in tests of cervical samples from 79 university students in the United States. Exposure to AAV was assessed further by serology. Using a whole virus AAV-2 sandwich enzyme-linked immunosorbent assay, we found no relationship between AAV antibodies and presence or grade of neoplasia in either the Jamaican study subjects or women enrolled in a U.S. cervical cancer case (n = 74) - control (n = 77) study. Overall, the data provide no evidence that AAV infection plays a role in cervical tumorigenesis or that AAV commonly infects cervical epithelial cells.(Au)

Development and evaluation of an enzyme-linked immunosorbent assay for serum Vi antibodies for detection of chronic Salmonella typhi carriers.

An enzyme-linked immunosorbent assay (ELISA) measuring, in serum, immunoglobulin G (IgG), IgM, and IgA to Vi capsular polysaccharide antigen that was tyraminated (Vi-Tyr) to increase its binding efficiency to microtiter plates was compared with the standard passive hemagglutination assay (PHA) as a screening test for chronic Salmonella typhi carriers. Initially, three populations were evaluated: 22 healthy U.S. adults, 17 young Chilean adults with acute typhoid fever, and 51 Chileans who had bacteriologically confirmed S. typhi chronic carriage. IgG-specific Vi-Tyr antibodies were preferentially present in the S. typhi chronic carrier state. A total of 44 of 51 (81%) chronic carriers, 0 of 22 (0%) healthy U.S. adults, and 2 of 17 (12%) Chileans with acute typhoid fever had reciprocal IgG Vi-Tyr ELISA antibody titers in serum of greater than or equal to 200. The IgG Vi-Tyr ELISA was then compared with the PHA as a screening test for chronic carriers in 141 Chilean female food handlers. One woman was serologically incriminated as a carrier by both the IgG ELISA and PHA; her coprocultures were positive for S. typhi. One other woman, identified as a carrier by PHA, was negative by culture and IgG ELISA. The IgG Vi-Tyr ELISA is as sensitive as the PHA (86 versus 76%) and as specific (95 versus 95%) in screening for chronic carriers.