Acute respiratory disease related to adenovirus infections had been controlled in military basic training for approximately 30 years by immunization with a single-dose, live, oral vaccine against adenovirus serotypes 4 and 7. The resurgence of adenovirus infections in U.S. military recruits after 1999 has been widely attributed to the termination of the production of the adenovirus vaccine in 1994 following a decision by the Department of Defense (DoD) not to further invest in product and facility upgrades. After the vaccine was no longer available by 1999, febrile respiratory disease caused by type 4 or 7 adenovirus rapidly returned to the recruit training bases.

The live, oral adenovirus type 4 vaccine was initially developed at the U.S. National Institutes of Health (NIH) in the 1960s and later manufactured as an enteric coated tablet by Wyeth for the DoD. The need for a vaccine against a second serotype (type 7) was discovered after the initial clinical results of the type 4 vaccine alone were disappointing. Production and distribution of the types 4 and 7 live virus vaccine continued under an Investigational New Drug (IND) filing until the vaccine was approved by the FDA in 1980. Ongoing surveillance demonstrated the adenovirus vaccine to be safe and highly effective. After the vaccine was no longer available to the DoD, Barr Laboratories and Teva Pharmaceuticals responded in 2001 to a DoD Request for Proposal (RFP) with a comprehensive proposal to redevelop a vaccine that would meet the performance of the previously successful vaccine formulation. The former manufacturer provided materials and technical information under an agreement with Barr. Development and re-introduction of the vaccine required that Barr/Teva work closely with industry, DoD civilian and military scientists and physicians to develop the vaccine and conduct the clinical development program required by the FDA.

ADV Vaccine Restoration Contract
The DoD base development contract awarded in 2001 for the restoration of the vaccine included the construction of a new dedicated facility in 2003 to produce the vaccine tablets and to lyophilize the formulated virus produced at a contract manufacturer. In order to rapidly proceed into Phase I clinical trials, the bulk virus manufactured by BioReliance was formulated and lyophilized at the WRAIR Pilot Bioproduction facility and shipped to the adenovirus tableting facility for final dosage form manufacturing. The tablet manufacturing facility is a new, single, pre-engineered, two-story building. The footprint of the building is approximately 9,900 sq. ft. with approximately 9,000 sq. ft. in mezzanine level space, resulting in a total building area of approximately 19,000. sq. ft.

After success with the Phase I trial, the DoD exercised the option for further product development and full clinical development, which included large-scale manufacturing for supply to conduct a Phase III clinical study. The Phase III study, which began in 2006 and included a total of approximately 4,000 volunteers from both the Army and the Navy, demonstrated the vaccine to be highly effective and safe. In order to provide for a rapid introduction of the vaccine as soon as possible after FDA approval, a low-rate initial production and supply contract was awarded by DoD to Barr/Teva in 2010, prior to Biologics License Applications (BLA) approval in March 2011. Subsequently, an interim supply contract, providing for as much as a two-year delivery of vaccine, was awarded in 2012 and is currently being fulfilled.

Restoration of the Adenovirus Vaccine: Challenges
To be of utility to the DoD, the contract awarded to Barr/Teva required the vaccine’s characteristics to meet or exceed a number of performance criteria, such as:

• Provide at least 80% protection of those persons immunized against adenoviruses, types 4 and 7, which was to be provided by a single dose and that booster doses not be required
• Provide a protective response within 30 days of receiving initial vaccination
• Provide protection for at least 56 days from the end of complete administration
• The vaccine will have a minimum shelf life of two or more years when stored between 2–8°C

Adenovirus Type 4 and Type 7 Vaccine, Live, Oral contains viable, selected strains of human adenovirus Type 4 and humanadenovirus Type 7 prepared in human-diploid fibroblast cell cultures (strain WI-38). The virus strains have not been attenuated. The cells are grown and the virus growth maintained in Dulbecco’s Modified Eagle’s Medium, fetal bovine serum, and sodium bicarbonate. The virus is harvested, freed of particulate cellular material by filtration, formulated and dried by lyophilization. The dried virus material includes monosodium glutamate, sucrose, D-mannose, D-fructose, dextrose, human serum albumin, potassium phosphate and plasdone C.

The final vaccine is composed of two enterically-coated tablets (one tablet of Adenovirus Type 4 and one tablet of Adenovirus Type 7) designed to pass intact through the stomach and release the live virus in the intestine. Each enteric-coated tablet contains an inner core tablet containing anhydrous lactose, micro crystalline cellulose, polacrilin potassium, magnesium stearate, and live adenovirus, either Type 4 or Type 7, at a potency of no fewer than 32,000 tissue-culture infective doses (4.5 log10 TCID50) per tablet. The outer tablet layer contains microcrystalline cellulose, magnesium stearate, and anhydrous lactose, with an enteric coating consisting of cellulose acetate phthalate and castor oil. The Type 7 tablet also contains FD&C Yellow #6 aluminum lake dye.

Critically, the new Teva tablet formulation is manufactured in a new dedicated facility using current production methods that are compliant with Good Manufacturing Practices (cGMP). The formulation is similar to the previous vaccine so it is administered as two separate tablets: one tablet containing adenovirus type 4 and one tablet containing adenovirus type 7. There were some minor changes and improvements to the formulation, including deletion of the antibiotics used in the production of the virus and removing the tartrazine dye in the type 7 tablet.

ADV Vaccine: Deployment Ready!
More than 13 years after the previous adenovirus vaccine became unavailable, the restoration of the new Adenovirus Vaccine was completed with an FDA-approved vaccine and ready for shipping to all U.S. military recruit training bases, including the Coast Guard.

As deployment approached, the DoD product manager and the logistician established, with Teva, a vaccine rollout working group to coordinate test shipments and plans for distribution. To support an effective deployment, test shipments to all bases were conducted to optimize and confirm packing and shipping methods. A DoD representative was sent to each of the basic training sites to help ensure consistency of vaccine handling and administration.

In October 2011, Teva began distributing the Adenovirus Vaccine. As of this writing, more than 385,000 doses (source: TEVA) have been shipped successfully to nine basic military training facilities, with no loss of vaccine during shipment. Within a few months after introduction of the vaccine, febrile respiratory disease and adenovirus isolation rates have fallen dramatically and continue to be maintained at a low rate by the continued use of the vaccine.

Successful restoration of the adenovirus vaccine proved to be a complicated task that went beyond a technology transfer and included optimization of the vaccine manufacturing process to meet current cGMP requirements of the FDA. The Department of Defense is now able to protect U.S. military recruits again from a serious disease during their initial training phase. However, as with any successful vaccine program, continued investment to maintain the program is uncertain, without the continued support of DoD officials, which is the only group currently utilizing this vaccine. 

References

• A double-blind, placebo-controlled study of the safety and immunogenicity of live, oral type 4 and type 7 adenovirus vaccines in adults. Lyons A, Longfield J, Kuschner R, Straight T, Binn L, Seriwatana J, Reitstetter R, Froh IB, Craft D, McNabb K, Russell K, Metzgar D, Liss A, Sun X, Towle A, Sun W. Vaccine. 2008 Jun 2;26(23):2890-8. doi: 10.1016/j.vaccine.2008.03.037. Epub 2008 Apr 10
• A phase 3, randomized, double-blind, placebo-controlled study of the safety and efficacy of the live, oral adenovirus type 4 and type 7 vaccine, in U.S. military recruits. Kuschner RA, Russell KL, Abuja M, Bauer KM, Faix DJ, Hait H, Henrick J, Jacobs M, Liss A, Lynch JA, Liu Q, Lyons AG, Malik M, Moon JE, Stubbs J, Sun W, Tang D, Towle AC, Walsh DS, Wilkerson D; Adenovirus Vaccine Efficacy Trial Consortium. Vaccine. 2013 Jun 19;31(28):2963-71. doi: 10.1016/j.vaccine.2013.04.035. Epub 2013 Apr 25

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Andrew C. Towle, Ph.D. is chief scientific officer at VaccGen International LLC. Abul Azad, M.Pharm, Ph.D. is a principal scientist at Teva Pharmaceuticals. For more information about this article, contact andy_t1@msn.com. The authors would like to thank the many people involved with the re-introduction of this important vaccine, including Alan Liss, Ph.D.; Carrie Yon; Tahseen Chowdhury, Ph.D.; Yi Luo, Ph.D.; Megan Corbett; Valerie Mulligan; John Ianacone; Annie Mathew; John Brown; Aaron Skeen and the many other contributors to the project from Barr/Teva Pharmaceuticals; Kenneth Eckels, Ph.D. from WRAIR.