Under the plan all military personnel, including new recruits, would begin receiving what was then a six-shot series of inoculations in the following fashion: Phase 1: Forces assigned now, or soon rotating, to high threat areas in Southwest Asia and Korea; Phase 2: Early deploying forces into high threat areas; Phase 3: Remainder of the force and new recruits; and Phase 4: Continuation of the program with annual booster shots. The AVIP and initial mandatory military use (1997-2000)
There were no published studies of AVAs safety in humans until the advent of the Anthrax Vaccine Immunization Program (AVIP). This program, initiated by the Clinton administration and announced by Secretary of Defense William Cohen in 1997, made the vaccine mandatory for active duty US service personnel. Vaccinations began in March 1998 with personnel sent to high-risk areas, such as South Korea and Southwest Asia. Also in 1998, MBPI was purchased by BioPort Corporation of Lansing, Michigan (jointly with former MBPI laboratory directors) for approximately $24 million. The same year, a particularly damning FDA report was issued resulting in the temporary suspension of AVA shipments from the production plant. Much controversy ensued due to the FDA infractions, the mandatory nature of the program, and to a public perception that AVA was unsafe — possibly causing sometimes serious side effects — and might be contributing to the highly politically charged malady known as "Gulf War syndrome".
Azacitidine is a ribonucleoside, so it is incorporated into RNA to a larger extent than into DNA. In contrast, decitabine (5-aza-2-deoxycytidine) is a deoxyribonucleoside, so it can only incorporate into DNA. Azacitidines incorporation into RNA leads to the disassembly of polyribosomes, defective methylation and acceptor function of transfer RNA, and inhibition of the production of proteins. Its incorporation into DNA leads to covalent binding with DNA methyltransferases, which prevents DNA synthesis and subsequently leads to cytotoxicity. It has been shown effective against human immunodeficiency virus in vitro and human T-lymphotropic virus. Inhibition of methylation
After azanucleosides such as azacitidine have been metabolized to 5-aza-2′-deoxycytidine-triphosphate (aka, decitabine-triphosphate), they can be incorporated into DNA and azacytosine can be substituted for cytosine. Azacytosine-guanine dinucleotides are recognized as substrate by the DNA methyltransferases, which catalyze the methylation reaction by a nucleophilic attack. This results in a covalent bond between the carbon-6 atom of the cytosine ring and the enzyme. The bond is normally resolved by beta-elimination through the carbon-5 atom, but this latter reaction does not occur with azacytosine because its carbon-5 is substituted by nitrogen, leaving the enzyme covalently bound to DNA and blocking its DNA methyltransferase function. In addition, the covalent protein adduction also compromises the functionality of DNA and triggers DNA damage signaling, resulting in the degradation of trapped DNA methyltransferases. As a consequence, methylation marks become lost during DNA replication.