Prevalence of gene sequences coding for hypervariable regions of Opa (protein II) in Neisseria gonorrhoeae

Opas (protein IIs) are a family of surface-exposed proteins of Neisseria gonorrhoeae. Each strain of N. gonorrhoeae has multiple (10-11) genes encoding for Opas. Identifiable elements in opa genes include the coding repeat within the signal sequence, conserve 5' and 3' regions, and hypervariable regions (HV1 and HV2) located within the structural gene. N. gonorrhoeae strains appear to have many biological properties in common that are either HV-region-mediated or associated with the presence of specific HV regions, suggesting that HV regions could be found in many clinical isolates. Oligonucleotides from three source strains representing three conserved regions of opa, 12 HV1 regions, and 14 HV2 regions were used by dot blot analysis to probe 120 clinical isolates of N. gonorrhoeae. The probe for the coding repeat hybridized to all 120 strains, the 3' conserved-region probe reacted with 98% of the strains, and the 5' conserved-region probe with 90% of the strains. Nine HV1 probes hybridized to 3.3-39.2% of the strains, and 13 of the HV2 probes hybridized to 1.7-25% of the isolates. Analysis of the number of probes that hybridized to each of the isolates showed that 19% did not hybridize with any of the HV1 probes and 25% did not hybridize with any of the HV2 probes. Approximately three-quarters of the isolates hybridized with one, two or three of the HV1 probes or one, two or three of the HV2 probes; 89% of the isolates hybridized to least one HV1 or one HV2 probe. The data indicate that some genes encoding HV regions of N. gonorrhoeae Opa proteins are widely distributed in nature.