UK researchers have accessed the genome of chlamydial and they believe that it could pave way for the development of a vaccine for the sexually transmitted disease.
For decades experts have been prevented from fully understanding the bacteria, which if undetected can make sufferers infertile.
The infection is part of a silent epidemic as most cases do not show symptoms and are left untreated.
It can cause pelvic inflammatory disease and lead to scarring of the fallopian tubes, causing infertility and higher risk of ectopic pregnancy.
"This is a very significant advance in the study of chlamydia and we are proud to be the first people to achieve this," the Daily Mail quoted Professor Ian Clarke, from the University of Southampton, as saying.
"Previously people have been unable to study chlamydial genetics and this has created a barrier to the comprehensive study of this disease.
"We, together with our colleagues in Israel, discovered that by treating the chlamydia with calcium ions we were able to introduce a piece of foreign DNA.
"This will open up the field of chlamydia research and will enable a better understanding of chlamydial genetics. It could lead to the development of new approaches to chlamydial vaccines and therapeutic interventions," he added.
To prove that they had accessed the chlamydial genome, the research team inserted the gene for a fluorescent protein into C. trachomatis which identified the chlamydial-infected cells by making them glow green.
The study has been published in the Public Library of Science journal PLoS Pathogens.