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Chlamydia vaccine as alternative to antibiotics for atherosclerosis

Since Chlamydia pneumoniae is believed to be involved in the pathogenesis of coronary artery disease, ACES study investigated whether antibiotic therapy with Azithromycin ( Zithromax ) to eliminate Chlamydia pneumoniae would reduce the risk of coronary events.
There was no beneficial effect associated with Azithromycin.

In the ACES ( Azithromycin and Coronary Events Study ) trial among 4,012 patients with documented stable coronary artery disease, a 12-month course of Azithromycin therapy, given once weekly, failed to reduce the primary end-point of death due to coronary heart disease, non fatal myocardial infarction, myocardial revascularization or hospitalization for unstable angina during a mean follow-up of 3.9 years.

The results did not differ when the participants were stratified according to sex, age, smoking status, presence or absence of diabetes mellitus, or Chlamydia pneumoniae serologic status at baseline.

Another study , PROVE-IT TIMI 22 ( Pravastatin or Atorvastatin Evaluation and Infection Therapy–Thrombolysis in Myocardial Infarction 22 ). evaluated a third generation fluoroquinolone, Gatifloxacin ( Tequin ).

Two years of treatment with Gatifloxacin, an antibiotic with bactericidal activity against Chlamydia pneumoniae, had no beneficial effect on clinical outcomes.

A total of 4162 patients who had been hospitalized for an acute coronary syndrome within the preceding 10 days were enrolled in the trial.

The rates of primary-end-point events at two years were 23.7 percent in the Gatifloxacin group and 25.1 percent in the placebo group .

Despite negative results, researchers still believe Chlamydia pneumoniae plays a role in the development of heart disease.
Chlamydia pneumoniae may induce early damage to the blood vessels, resulting in antibiotic inefficacy.

A vaccine against Chlamydia might be a practical treatment.

In order to identify new potential vaccine candidates, Chiron’s researchers in Siena ( Italy ) recently screened the Chlamydia pneumoniae ( Cpn ) genome and described 53 recombinant proteins which elicited antibodies binding to purified Cpn cells.
Six proteins in this group can also induce in vitro neutralizing antibodies.
Furthermore, four of the six in vitro neutralizing antigens ( Pmp2, Pmp10, OmpH-like and enolase ) could inhibit Cpn dissemination in a hamster model.
The results showed that these Chlamydia pneumoniae proteins are immunoaccessible in infectious EB ( metabolically inert elementary body ).

Source: The New England Journal of Medicine, 2005