✓IROGENETICS 
TROVAC (FPpp) INFORMATION 
A. ORIGIN OF THE TROVAC (FPpp) VECTOR 
1. Parental organism: The parental organism FP-1 is an attenuated vaccine 
strain of fowlpox virus originally isolated from a pox scab on a chicken in 
France. The virus was attenuated by approximately 50 serial passages in 
chicken embryonated eggs followed by 25 passages on chicken embryo 
fibroblast cells. In September 1989, a master seed virus DCEP25 was 
established by Rhone Merieux, Lyon, France. The virus was imported to the 
U.S. by Select Laboratories, Inc. under permit #20374. The virus is used by 
Rhone Merieux to produce a live fowlpox vaccine registered in France as 
"DIFTOSEC CT". 
2. Description of vector: The fowlpox virus FP-1 was sent to Virogenetics 
from Select Laboratories, Inc. under USD A permit #21671 in September 1989 
After four successive plaque purifications, one plaque isolate was amplified in 
primary CEFs to establish a seed stock virus designated as TROVAC (FPpp). 
No other genetic modifications were used to produce the TROVAC (FPpp) 
vector. 
B. BIOLOGICAL PROPERTIES 
1. Host/range specificity: Productive replication of avipoxvirus is naturally 
restricted to avian species (Esposito, 1991 and Cox et al., 1991). This 
characteristic has been preserved in TROVAC (FPpp) and recombinants based 
on TROVAC (FPpp) (Appendices A, B, and C). In vitro it grows in primary 
and secondary CEFs and chick dermal cells, but not in mammalian cells 
(Appendix A). Attempts were made to adapt FP-1 or the recombinant vFP3 
to grow in non-avian cells by a series of six sequential blind passages on Vero 
and MRC-5 cells without success (Appendices B & C). 
Fowlpox virus has been used as a live attenuated vaccine since the 1920s to 
control the disease in poultry (Appendix D). In the history of the virus as a 
vaccine in the poultry industry, there are no reports of transmission of the 
virus from vaccinated birds to humans or any other species (Appendices C & 
E). 
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