Development of an inhibition ELISA test for the detection of non-capsid polyprotein 3ABC in viral suspensions destined for inactivated foot-and-mouth disease vaccines.

The use during the last decade of immuno-enzymatic tests based on the detection of antibodies to the non-capsid proteins (NCPs) of foot-and-mouth disease virus (FMDV) to assess viral circulation, irrespective of vaccination, supported the incorporation into the OIE code of the 'free from FMDV with vaccination' category and opened the way to a 'vaccination to live' policy. Eradication programmes in South America include systematic vaccination accompanied by large serosurveys through NCP antibody testing to ensure the absence of residual viral activity. For correct interpretation of serosurveys, a major prerequisite is that vaccines made of semi-purified preparations of inactivated virions do not contain levels of NCPs, which upon proper presentation conditions, could induce an antibody response under the conditions for field immunization. This work describes the development of an inhibition ELISA to detect NCP polyprotein 3ABC in viral suspensions destined for vaccine production as an in-process control during vaccine manufacture. Antibody responses against NCP 3ABC in vaccinated and revaccinated cattle, induced by vaccines with different purification processes and formulations, are discussed.

Immune response in cattle induced by inactivated rabies vaccine adjuvanted with aluminium hydroxide either alone or in combination with avridine.

In a comparative study of two commercial baby hamster kidney rabies vaccines produced in Brazil, the authors were able to demonstrate the following: a) both vaccines provoked a high level of antibody response and protection against challenge in cattle b) in primary vaccination, at least, the addition of avridine (a synthetic lipoidal amine) enhances the immune response in terms of the level and persistence of antibody c) over 90% of cattle vaccinated with either vaccine were protected against experimental challenge one year after revaccination, and the antibody response profile indicated that these vaccines were capable of maintaining antibody titres above protective levels for more than two years after revaccination. On the basis of these results, the authors recommend optional revaccination of young animals (i.e. "primo-vaccinates") at six months of age. Thereafter, annual revaccination should be sufficient to ensure high levels of antibody between vaccination cycles.

Efficacy of avridine as an adjuvant for Newcastle disease virus antigen in chickens.

Avridine, a lipoidal amine with interferon-inducing and adjuvant properties, was an effective adjuvant for Newcastle disease antigen (NDA) in chickens. Eleven vaccine lots were evaluated: 2 commercial water-in-oil vaccines, 4 experimental oil emulsion vaccines, 4 avridine-containing vaccines, and a control lot of nonadjuvanted antigen. Avridine significantly enhanced the immunologic responses of chickens against NDA. Chickens vaccinated with the avridine-containing vaccines had significantly higher antibody titers (hemagglutination inhibition) than did chickens vaccinated with the commercial vaccines. Experimental oil emulsion vaccines prepared from the same antigens as avridine-adjuvanted vaccines induced higher hemagglutination inhibition antibody titers after primary but not after booster vaccination. Use of avridine as an adjuvant for NDA in vaccines for chickens induced immunologic protection rates similar to those induced by oil emulsion vaccines, without causing the reactogenic and tissue residue problems associated with the use of oil vaccines in chickens.