Genomic Stability of Genotyping Markers in Chlamydia trachomatis

is consensual due to the dissimilar genetic characteristics or discriminatory power of the loci enrolled in each of those. Although it is assumed that the typing schemes should ideally ensure that the chosen loci are stable over the course of evolution, this issue is of difficult assessment. Labiran et al. (2012) have now presented a study where they have assessed the stability of some regions of the C. trachomatis genome by using innovate approaches. They have used the genetic markers from the described typing schemes that provide the highest Simpson index of diversity: the multisequence typing (MST) system described by Klint et al. (2007) and the multi locus variable number tandem repeat (VNTR) analysis (MLVA-ompA) described by Pedersen et al. (2008). Labiran et al. (2012) have initially evaluated the stability of those genetic markers through the first stages of adaptation of C. trachomatis to cell culture. This is interesting as the first attempt to study mutational patterns over adaptation to cell culture had been performed back in 1998 (Stothard et al., 1998), by studying solely the stability of ompA over 20 in vitro passages. Now, by analyzing three VNTR besides ompA, the authors undoubtedly increase the chances of observing genetic alterations, as these loci possess a high discriminatory power. Furthermore, as the repeated sequences of VNTR loci are generated as a consequence of an increased error rate during DNA replication at these regions, they are hypothetically more prone to additional variation. In this first approach, the authors found no alterations in those genomic regions by studying seven clinical isolates over eight passages. The initial inoculations were properly done from primary swabs in order to avoid previous contact of the strains with the in vitro system. Interestingly, the eight passages represent about 16 days in culture aiming to reflect the in vivo estimated period for appearance of symptoms for C. trachomatis infection of both genitalia and conjunctivae (Black, 1997). There is no doubt that Genomic stability of genotyping markers in Chlamydia trachomatis