Comparison of the safety and efficacy of a recombinant feline leukemia virus (FeLV) vaccine delivered transdermally and an inactivated FeLV vaccine delivered subcutaneously.

The efficacy of a new recombinant FeLV vaccine (rFeLV), delivered transdermally via a needle-free delivery device was compared to that of an inactivated FeLV vaccine (FeLV-k), administered subcutaneously, with a conventional needle and syringe. Kittens were immunized with either rFeLV (0.25 ml, transdermal) or FeLV-k (1 ml, subcutaneous); or they were sham-vaccinated with physiologic saline (0.25 ml, transdermal). Two vaccinations were administered 21 days apart. Injection sites were monitored for any acute or subacute reactions relative to vaccine administration. Four weeks following the final vaccination, all cats were subject to oro-nasal FeLV challenge. Blood was collected for determination of FeLV antigenemia (p27) at weekly intervals beginning three weeks post-challenge. All of the vaccinated cats from both groups resisted FeLV challenge; and 90% of the control cats developed persistent FeLV antigenemia in response to challenge. No acute or persistent injection site reactions were observed. The rFeLV, delivered transdermally, provides protection against persistent FeLV antigenemia following a robust challenge that is equivalent to that of FeLV-k.

Vaccination of wildlife against rabies: successful use of a vectored vaccine obtained by recombinant technology.

The impact of recombinant technology in veterinary and human medicine can only be hypothesized at this time. The development of vaccines and other biological products that go beyond the abilities of conventional products demonstrates the benefits of this new technology. Raboral V-RG was developed as an alternative rabies vaccine with the novel attribute of being effective by the oral route. Within 10 years after its first application as an experimental vaccine in European, red foxes it developed into a useful tool and is being used to curtail rabies epizootics in three wildlife species in the United States. The use of this vaccine can be considered as monumental in contributing to the control of rabies in species that were at one time considered to be incapable of vaccination in large-scale campaigns.