• Provide informed consent prior to initiation of any trial procedures.

• Be able to understand and agrees to comply with planned trial procedures and be available for all trial visits and phone calls.

• Healthy male or non-pregnant female, between 18 and 59 years of age (Group 1) or between60 and 75 years of age (Group 2), inclusive, at time of trial vaccination.

• Women of childbearing potential must agree to use or have practiced true abstinence or use at least one acceptable primary form of contraception. Note: These criteria are applicable to females in a heterosexual relationship and child-bearing potential (i.e., the criteria do not apply to subjects in a same sex relationship).

• Women of childbearing potential must have a negative urine or serum pregnancy test within 24 hours prior to each vaccination.

• Male subjects of childbearing potential* must use condoms to ensure effective contraception with a female partner of childbearing potential from vaccination until 90 days after vaccination. Such female partners must also use an acceptable form of primary contraception as described under inclusion criterion #4. If barrier methods are to be used, then double barrier methods of protection are required, i.e. male condom, in combination with a cap, diaphragm, or sponge with spermicide. *Biological males who are post-pubertal and considered fertile until permanently sterile by bilateral orchiectomy or vasectomy.

• Male subjects agree to refrain from sperm donation from the time of vaccination until 90 days after vaccination.

• Female subjects agree to refrain from egg donation from time of vaccination until 90 days after vaccination.

• In good health.