Validation of an in vitro assay for the determination of rabies antigen.

The modified antibody binding test, an in vitro method, was validated by a number of studies and was used as a reliable method for in process controls in the manufacture of rabies vaccines for man and animals over the last 6 years. A calculation was made showing the number of laboratory mice which were not needed for animal experiments because these were substituted by the in vitro method mentioned above.

Purified chick embryo cell (PCEC) rabies vaccine for human use. Laboratory data.

A new inactivated rabies vaccine (Purified Chick Embryo Cell vaccine) for use in humans has been developed. The FLURY-LEP C25 strain of rabies virus was adapted to propagate in primary chick embryo cell cultures. The antigen was purified and concentrated by continuous density gradient centrifugation and inactivated by Betapropiolactone. The PCEC-rabies vaccine was tested for innocuity, tolerability and protective capacity in a series of laboratory tests and compared with Human Diploid Cell Strain rabies vaccine (HDCSV) of similar antigenicity. The results of the laboratory tests indicated that this new vaccine was excellently tolerated and that its protective activity met the high standard of HDCS-vaccine, conditions which were imposed on the PCEC-vaccine before clinical trials in man were initiated.

A new inactivated tissue culture rabies vaccine for use in man. Evaluation of PCEC-vaccine by laboratory tests.

A new inactivated rabies vaccine (purified chick embryo cell vaccine) has been developed using the Flury LEP-C 25 strain of rabies virus propagated in primary chick embryo cell cultures. The antigen was purified and concentrated by continuous density gradient centrifugation and inactivated by betapropiolactone. This vaccine was tested for innocuity, tolerability and protective capacity in a series of laboratory tests and compared with human diploid cell strain (HDC)-vaccines of similar antigenicity. The results indicated that this new vaccine was excellently tolerated and that its protective activity met the high standard of HDC-vaccine, conditions which were imposed on this vaccine before entering clinical trials in man.

Purification, concentration and evaluation of rabies virus antigen.

A number of concentration and purification procedures for rabies virus antigen have been developed during the last decades but only ultrafiltration and density gradient centrifugation have been found suitable for large scale production. The antibody binding test developed by Arko, Wiktor and Sikes was modified and was found useful for evaluation of inactivated antigen-concentrates. This test was used as an 'in process' control. Three examples of practical experience are reported and discussed.

[NIH potency tests with inactivated rabies vaccines (author's transl)]. / Zur Wirksamkeitsprüfung von inaktivierten Tollwut-Gewebekulturimpfstoffen im NIH-Test.

63 NIH tests were analysed. A BPL inactivated tissue culture rabies vaccine No. 108 was compared with the national standard vaccine A 18 fourteen times in different tests. The results show that reproduction of results is unsatisfactory with the NIH test and that this test in its present traditional method with two injections is not very suitable for satisfactory potency evaluation of inactivated rabies vaccines. Proposals for modifications are made.

[Efficacy of disinfectants against rabies virus (author's transl)]. / Zur Wirksamkeit von Desinfektionsmitteln gegenüber dem Tollwutvirus.

A variety of disinfectants was tested against, their efficacy against Rabies virus Flury LEP strain. The efficacy was tested by intracerebral inoculation of a mixture of virus and disinfectant into 11-15 g white mice after evaluation of the intracerebral toxic dose. Two disinfectants, based on Phenolecompound, showed a marked superior effect compared with other disinfectants. One disinfectant based on quarternary Ammoniumbase showed insufficient efficacy.

Administration of human interferon to rabies virus-infected monkeys after exposure.

The treatment of rabies-infected cynomolgus monkeys (Macaca fascicularis) with human interferon after exposure was studied. The monkeys were infected with rabies street virus by the intramuscular route; larger than or equal to 24 hr after infection, human interferon was administered intramuscularly or by lumbar spinal injection into the cerebrospinal fluid. Whereas 90% of the infected untreated monkeys died, 40%-80% of animals treated with interferon survived. No or only low levels of neutralizing antibody to rabies virus were found in the sera of monkeys that survived after a single intramuscular injection of human interferon. Distinctly higher antibody titers, however, were detected in the sera of surviving monkeys that had been given six consecutive intralumbar doses of interferon beginning three days after infections. Therefore, we conclude that in these monkeys rabies virus propagated until it spread into the central nervous system, where further viral replication was inhibited by the human interferon administered by the intralumbar route.