Systematic Veterinary Virology

VACCINES

• Pasteur type vaccine: One of the oldest vaccines against rabies. Prepared by injecting the fixed virus into rabbits. The brain cords are collected and dried by dessication and treating with KOH. Not in use at present.
• Nervous tissue preparation and phenolized (Fermi, Semple and Umeno-doi vaccines): This consisted of a 5% suspension of infected animal nervous tissue which had been inactivated (eg. the Semple vaccine was derived from phenol-inactivated infected rabbit brain), These preparations are now out of date as they were associated with the rare complication of demyelinating allergic encephalitis. This appears to be related to myelin basic protein in the vaccine. This complication was shown to occur in 4.6 case for 1000 persons vaccinated by the Semple vaccine. The case-fatality proportion was 3.13%. The Semple vaccine is still used in some developing countries. A suckling mouse brain vaccine is used in some Central and S.American countries.
• UV treated vaccines (Webster): Inactivated vaccines prepared from brain of infected animals, which were exposed to UV rays. UV rays readily kill the rabies virus.
• Duck Embryo Vaccine (Peck) - this vaccine strain is grown in embryonated duck eggs and is inactivated with B-propriolactone. This vaccine has a lower risk of allergic encephalitis. However, it is considerably less immunogenic and does have minor side effects. Almost all vaccinees experience local reactions, 33% have constitutional symptoms such as fever, malaise, myalgia, and generalized lymphadenopathy.
• Live vaccines – (Hoegyes): Live fixed viruses are given at a very low level (below the infective dose).
• Avianized vaccines (Koprowsky and Cox): The Flurry strain of rabies virus grows in chicken embryos. It loses its pathogenicity after 40-50 passages in embryos for rabbits and dogs (referred as low egg passage vaccines – LEP) and loses the pathogenicity completely except for mice after 180 passages (referred as high egg passage vaccines – HEP). HEP were used for humans and LEP were used only for dogs and not for any other animals. 
• Human Diploid Cell Vaccine (HDCV): HDCV was introduced in 1978. It is a grown on WI-38 (U.S.) or MRC-5 (Europe) cells. The vaccine is highly effective, in several studies, antibodies have been demonstrated in 100% of all recipients. Serious adverse reactions to HDCV are extremely rare. However, the vaccine is very expensive, as human cell cultures are more difficult to handle than other animal cell culture systems.
• Efforts are being made to use other inexpensive cell culture systems such as VERO cells.