Recombinant DNA Advisory Committee - 06/7-8/93 
Office of Veterinary Biologies has conducted risk analyses and has recommended that 
the physical containment levels for TROVAC and ALVAC be reduced from BL2 to 
BL1. 
Review--Dr. Moss (Presented by Dr. Walters) 
In the absence of Dr. Moss, NIH, Bethesda, Maryland, an ad hoc expert on poxviruses, 
Dr. Walters summarized Dr. Moss' written review of the request. Dr. Moss is of the 
opinion that there is little or no inherent risk to individuals in working with these viruses. 
The only possible risk that could be foreseen would be inadvertent immunization with a 
recombinant protein expressed by these vectors. Dr. Moss recommended the use of the 
proposed vectors at BL1 containment unless there is reason to believe that immunizing 
amounts of the gene products would provide an additional risk. 
Other Comments 
Mr. Capron asked about risk of inadvertent immunization alluded to in Dr. Moss' review. 
Dr. Straus described one example in which an individual exposed to HTV proteins 
produced by poxvirus vectors could be seropositive for HIV even though the individual is 
not infected by HIV. Another example would be respiratory syncytial virus infection in 
which a vaccinated individual may react more severely to viral infection than an 
unvaccinated child. Such risks are not due to the vectors per se but are due to the 
particular proteins expressed by these vectors. 
Many other written comments had been submitted in support of the proposed 
reclassification based on the highly attenuated characteristics and restricted host ranges 
of these vectors. These written reviews were by the following scientists: Dr. W. K. 
Joklik of Duke University Medical Center; Dr. Peter W. Mason of the Agricultural 
Research Service, USD A; Dr. Joanne Maki, Rhone Merieux, Inc.; Dr. David E. Lanar, 
Walter Reed Army Medical Center; Dr. Bert Jacob of Arizona State University; Dr. 
Robert E. Shope of Yale University; and Dr. Mary Lou Clements of Johns Hopkins 
School of Hygiene and Public Health. 
Investigator Response--Dr. Paoletti 
Dr. Paoletti explained that he is requesting reclassification of three vectors that are 
currently classified as Class 2 pathogens. NYVAC is based on the Copenhagen strain of 
vaccinia virus in which 18 viral genes have been deleted; ALVAC is based on an 
attenuated strain of canarypox; and TROVAC is based on an attenuated strain of 
fowlpox virus. Dr. Post asked what additional advantages would be gained from this 
reclassification since permission for field testing has already been granted by the USD A. 
Dr. Paoletti said that approval of this request would facilitate the transfer and 
Recombinant DNA Research, Volume 17 
[593] 
