The purpose of this study is to determine if BHT-3009 decreases inflammation (measured by gadolinium enhancing MRI lesions) in the brains of people with relapsing remitting multiple sclerosis.

People with multiple sclerosis are thought to have abnormal immunity. Usually the body's immune system attacks only foreign substances, but people with MS have abnormal immunity, where the immune system attacks normal proteins, one of which is a protein found in the brain called MBP (myelin basic protein). This abnormal immunity causes inflammation in the brain resulting in nerve damage. BHT-3009 is a drug that is designed to decrease this abnormal immunity to MBP. BHT-3009 is a DNA plasmid that contains the gene for MBP. Plasmids are circular pieces of DNA that are being tested in clinical trials for their ability to alter patients' immune systems. Two different doses of BHT-3009 will be tested to determine if there are any differences in their safety or effects on inflammation.

Treatment in this study is 3 doses every two weeks for 6 weeks, followed by a dose every 4 weeks for a total of 13 doses in 44 weeks.

Inclusion Criteria:

1. Definite diagnosis of multiple sclerosis by the McDonald criteria.
2. Screening cranial MRI demonstrating lesions consistent with MS.
3. One or more relapses within the previous year.
4. Clinically stable (no relapses) for > 50 days before beginning screening procedures and during the screening period.
5. EDSS 0 to 3.5 inclusive.
6. Age > 17 years and < 56 years.
7. Willing and able to give informed consent.
8. WBC >3,000; platelets >100,000; hemoglobin > 10.0 g/dl.
9. AST, ALT, bilirubin < 2.0 x upper limit of normal.
10. Creatinine < 2.0 x upper limit of normal.
11. Negative test for HIV.

Exclusion Criteria:

1. Primary progressive, secondary progressive or progressive relapsing MS.
2. More than 5 gadolinium-enhancing lesions on the first screening MRI.
3. High-dose corticosteroids (e.g. > 500 mg methylprednisolone or equivalent per day for 3 or more days) within 50 days prior to beginning screening procedures.
4. Previous stem cell transplantation, total lymphoid radiation, or cytotoxic therapy.
5. Treatment with interferon, glatiramer acetate or other approved disease-modifying agent for > 180 days (lifetime total of all agents).
6. Treatment with an approved disease modifying agent within 180 days of beginning screening procedures.
7. Previous treatment of MS with an experimental agent including off-label use of approved drugs. (Allowed with approval of the Medical Monitor.)
8. Prior therapy with natalizumab (Tysabri).
9. Pregnant or lactating women.
10. Unwilling to use a medically acceptable form of birth control (e.g. hormonal contraception, intrauterine device, double barriers, sterilization of self or partner).
11. Clinically significant ECG abnormalities (e.g. acute ischemia or life-threatening arrhythmia).
12. Medical condition or social circumstances that would in the opinion of the investigator prevent full participation in the trial or evaluation of study endpoints.
13. Implanted pace makers, defibrillators or other metallic objects on or inside the body that limit performing MRI scans.
14. Known hypersensitivity or allergy to gadolinium.