Concordance of ompA types in children re-infected with ocular Chlamydia trachomatis following mass azithromycin treatment for trachoma

• Published in: PLoS neglected tropical diseases 2022-03, Vol.16 (3), p.e0010237-e0010237
• Main Authors: Mosenia, Arman, Chin, Stephanie A, Alemayehu, Wondu, Melese, Muluken, Lakew, Takele, Zhou, Zhaoxia, Doan, Thuy, Cevallos, Vicky, Lietman, Thomas M, Keenan, Jeremy D
• Format: Article
• Language: English
• Subjects: Antibiotics; Antigens; Azithromycin; Azithromycin - therapeutic use; Biology and Life Sciences; Child; Children; Children & youth; Chlamydia; Chlamydia trachomatis; Chlamydia trachomatis - genetics; Conjunctiva; Demographic aspects; Disease control; Diseases; Distribution; Dosage and administration; Drug therapy; Genetic aspects; Health aspects; High frequency; Households; Humans; Immunity; Infections; Major outer membrane protein; Mass; Mass distribution; Medicine and Health Sciences; Membrane proteins; Nucleotide sequence; OmpA protein; Patient outcomes; PCR; Polymerase Chain Reaction; Relapse; Research and Analysis Methods; Sequencing; Sexually transmitted diseases; STD; Trachoma; Trachoma - drug therapy; Trachoma - epidemiology; Trachoma - prevention & control; Tropical diseases; Vaccines
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0010237

The chlamydial major outer membrane protein, encoded by the ompA gene, is a primary target for chlamydial vaccine research. However, human studies of ompA-specific immunity are limited, and prior studies have been limited in differentiating re-infection from persistent infection. The purpose of this study was to assess whether children living in trachoma-endemic communities with re-infections of ocular chlamydia were more likely to be infected with a different or similar genovar. The study included 21 communities from a trachoma-hyperendemic area of Ethiopia that had been treated with a mass azithromycin distribution for trachoma. Conjunctival swabbing was offered to all children younger than 5 years of age at baseline (i.e., pre-treatment), and then at follow-up visits 2 and 6 months later. Swabs were subjected to polymerase chain reaction (PCR) to detect C. trachomatis. A random sample of 359 PCR-positive swabs, stratified by study visit and study community, was chosen for ompA sequencing. In addition, ompA sequencing was performed on all swabs of 24 children who experienced chlamydial re-infection (i.e., positive chlamydial test before treatment, negative test 2 months following mass distribution of azithromycin, and again a positive test 6 months post-treatment). ompA sequencing was successful for 351 of 359 swabs of the random sample and 44 of 48 swabs of the re-infection sample. In the random sample, ompA types clustered within households more than would be expected by chance. Among the 21 re-infected children with complete ompA data, 14 had the same ompA type before and after treatment. The high frequency of ompA concordance suggests incomplete genovar-specific protective immunity and the need for multiple antigens as vaccine targets.