Canadian researchers have laid the first bricks in the development of a
vaccine against chlamydia – one of the most prevalent sexually transmitted infections in the United States and elsewhere globally.
The Centers for Disease Control and Prevention reported over 1.4 million chlamydial infections in 2012. But this number may not capture a large portion of people who don’t know they have chlamydia. Symptoms for the infection are often not noticeable, and people only get checked if they experience severe symptoms like painful urination, swelling, or abnormal discharge. So far, condoms remain the best recommended protection against chlamydia (aside from abstinence).
"Vaccine development efforts (for chlamydia) in the past three decades have been unproductive and there is no vaccine approved for use in humans," said David Bulir, researcher at the M. G. DeGroote Institute for Infectious Disease Research at McMaster University, and first author of the study. A huge hurdle for such vaccine is the number of strains of the pathogen, and the strains are have the capacity to mutate very quickly.
To address this issue, Bulir and his team focused on the bacterial species responsible for the most cases of chlamydia:
Chlamydia trachomatis. They then selected three proteins involved with growth and replication – core cellular activities bacteria rely on to infect new hosts. The three proteins were fused into one protein, known as BD584, and presented as an antigen to trigger a host immune response against chlamydia.
In lab tests with mice, the team showed two doses of the prototype vaccine, delivered through a nasal spray, were sufficient to protect the mice against chlamydia exposure. Compared to the unvaccinated mice, the mice treated with BD584 had a lower number of bacterial count in their system, which indicated they cleared the infection faster. In addition, the vaccinated mice had less symptoms associated with their reproductive organs.
"Vaccination would be the best way to way to prevent a chlamydia infection, and this study has identified important new antigens which could be used as part of a vaccine to prevent or eliminate the damaging reproductive consequences of untreated infections," said Bulir.
"The vaccine would be administered through the nose,” explained study author and PhD student at McMaster University Steven Liang. “This is easy and painless and does not require highly trained health professionals to administer, and that makes it an inexpensive solution for developing nations," he said.
Though the results are highly encouraging, it’s worthwhile to remember that the road to an approved vaccine is long and tricky. And so far, the team has only begun. Now that the mice study is completed, the team anticipates more animal trials. "We will trial the vaccine on other animal models before moving on to human trials," said Bulir.
Additional source:
BBC News
