Lymphogranuloma venereum (LGV) ompA -subvariants of the Portuguese collection of Chlamydia trachomatis, 2007-2023

Background: Lymphogranuloma venereum (LGV) is a sexually transmitted infection caused by Chlamydia trachomatis ompA-genotypes L1-L3, with increasing numbers of detected cases across Europe. Here, we analysed diversity and temporal distribution of the LGV ompA-subvariants detected in Portugal between 2007 and 2023, in order to better understand the dissemination and diversification landscape of LGV strains. Methods: The collection of the Portuguese National Reference Laboratory includes 1188 LGV ompA-genotyped samples between 2007 and 2023. In-depth analysis of the diversity of LGV ompA-subvariants circulating in Portugal across the years was performed, identifying newly described subvariants and integrating this data in a comprehensive compilation with all representative LGV ompA-subvariants described globally. Results: L2 ompA-variant (L2/434/Bu) was consistently the most frequently detected in our collection, with annual proportions ranging from 34.0% to 82.9%, between 2016 and 2023. L2bV5 was the second most frequent followed by L2b, ranging from 5.0% to 27.9% and 2.6% to 23.7% across the years, respectively, from 2017 to 2023. We highlighted the emergence and considerable increase in circulation of L1-like ompA-subvariants in recent years, representing 13.7% of LGV sequences in 2023. We also identified 13 novel LGV ompA-subvariants that had not been described before, differing by up to three mutations from the respective genotype reference sequences. Conclusions: This study contributes to the worldwide picture of the LGV molecular epidemiology, highlighting the importance of long-term molecular surveillance to monitor the circulation and geographical spread of LGV and to timely identify and track new strains, such as the recently emerging L1-like ompA-subvariants.