CT694 and pgp3 as serological tools for monitoring trachoma programs

• Published in: PLoS neglected tropical diseases 2012-11, Vol.6 (11), p.e1873-e1873
• Main Authors: Goodhew, E Brook, Priest, Jeffrey W, Moss, Delynn M, Zhong, Guangming, Munoz, Beatriz, Mkocha, Harran, Martin, Diana L, West, Sheila K, Gaydos, Charlotte, Lammie, Patrick J
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - therapeutic use; Antibodies, Bacterial - blood; Antigen-antibody reactions; Antigens, Bacterial - immunology; Azithromycin - therapeutic use; Bacterial Proteins - immunology; Biology; Care and treatment; Child; Child, Preschool; Children; Diagnosis; Drug Monitoring - methods; Equipment and supplies; Female; Health aspects; Humans; Immune response; Immunoglobulin G - blood; Infant; Lymphogranuloma Venereum - diagnosis; Lymphogranuloma Venereum - drug therapy; Male; Medicine; Methods; Sensitivity and Specificity; Serodiagnosis; Tanzania; Trachoma
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0001873

Defining endpoints for trachoma programs can be a challenge as clinical signs of infection may persist in the absence of detectable bacteria. Antibody-based tests may provide an alternative testing strategy for surveillance during terminal phases of the program. Antibody-based assays, in particular ELISAs, have been shown to be useful to document C. trachomatis genital infections, but have not been explored extensively for ocular C. trachomatis infections. An antibody-based multiplex assay was used to test two C. trachomatis antigens, pgp3 and CT694, for detection of trachoma antibodies in bloodspots from Tanzanian children (n = 160) collected after multiple rounds of mass azithromycin treatment. Using samples from C. trachomatis-positive (by PCR) children from Tanzania (n = 11) and control sera from a non-endemic group of U.S. children (n = 122), IgG responses to both pgp3 and CT694 were determined to be 91% sensitive and 98% specific. Antibody responses of Tanzanian children were analyzed with regard to clinical trachoma, PCR positivity, and age. In general, children with more intense ocular pathology (TF/TI = 2 or most severe) had a higher median antibody response to pgp3 (p = 0.0041) and CT694 (p = 0.0282) than those with normal exams (TF/TI = 0). However, 44% of children with no ocular pathology tested positive for antibody, suggesting prior infection. The median titer of antibody responses for children less than three years of age was significantly lower than those of older children. (p