The STD-CRC laboratory core will: 1) provide necessary specialized microbiological and laboratory expertise for investigators performing clinical, epidemiological and behavioral projects within the STD-CRC; 2) facilitate the rapid application of new advances in basic sciences or molecular biology to relevant clinical and epidemiologic projects within the STD-CRC; 3) serve as a national and international reference laboratory for other investigators studying STDs; and 4) maintain a gonorrhea registry to continue assessment of factors associated with reinfection with Neisseria gonorrhoeae. The laboratory expertise provided in the core will consist of highly specialized laboratory tests that are not routinely available even in other research laboratories but are integral to the success of proposed epidemiological or clinical research. Examples of such tests include determination of C. trachomatis serovars; determination of gonococcal auxotypes and serotypes; PCR and LCR tests for chlamydia; Pulse field gel electrophoresis (PFGE) analysis of N. gonorrhoeae; MOMP nucleotide sequences of selected chlamydia strains; and Micro IF serology for C. trachomatis. Provision of these and other tests in a central core laboratory ensures that they will be performed by technically experienced investigators, reduces costs by economy of scale, and makes these tests available to researchers conducting behavioral and epidemiological studies who might otherwise not have access to laboratory collaborators. Such availability will foster the use of microbiological endpoints in behavioral studies. While it is not the purpose of the laboratory core to support basic science work, the core will actively seek to transfer appropriate technology from basic science laboratories to relevant clinical and epidemiological projects. For example, we propose the further development and implementation of a PFGE based typing system for gonococci that will demonstrate heterogeneity even among strains of the same auxotype and serovar, providing a much more powerful tool for demonstrating strain diversity. The procedures performed within the laboratory core will be available as a national and international resource for other investigators, eliminating the need for them to develop expensive and technically demanding tests.