Advances in fowlpox vaccination.

Abstract

Abstract Fowlpox virus (FWPV) is widespread, causing disease of mature poultry with significant social or economic impact and some mortality, which is higher in the diphtheritic form of the disease. Vaccines against the disease were some of the earliest developed for livestock. They are live vaccines based on attenuated isolates or passaged derivatives of FWPV, or the serologically closely related pigeonpox virus. Relying heavily on approaches developed for vaccinia virus, FWPV was developed as a live recombinant vaccine vector for use in poultry. Licensed, commercial, recombinant FWPV vaccines are available against avian influenza, Newcastle disease and infectious laryngotracheitis. Causing disease only in birds, FWPV is nevertheless able to infect mammalian cells, express proteins and induce immune responses, both humoral and cellular, which may in some circumstances be protective (a feature shared with another member of the genus, canarypox virus). Blocked during morphogenesis (or before) in mammalian cells, it has an extremely high safety profile as a live recombinant vaccine vector for use in humans and other mammals, as demonstrated in numerous clinical trials. Relatively low potency in mammals has been addressed by using prime-boost regimes and by co-expression of host cytokines (an approach also trialled in poultry) or co-stimulators. New generation vectors may involve deletion of FWPV immunomodulators to improve efficacy.