Neutralization kinetics studies with type SAT 2 foot-and-mouth disease virus strains

Evaluation of Immunogenicity of Clostridium perfringens Type B Toxoid and Inactivated FMD (O) Virus with Adjuvant (ISA70-MF59)

Foot and mouth disease (FMD) and enterotoxemia are important diseases of hoofed animals. Vaccination against livestock pathogens, especially these two diseases, plays a key role in the prevention and control of these diseases. The use of combined vaccines with the aim of creating a better immune response and producing cheaper vaccines is a great contribution to Vaccine industry. This research aimed to compare the immunogenicity of FMD (O) and Clostridium perfringens type B toxoid along with adjuvant (MF59) and Montanide (ISA70) to create the best immunogenicity. To investigate the immune responses of vaccines, it was injected into an animal model, and the antibody titer was measured by enzyme-linked immunosorbent assay (ELISA) test and VN antibody titer. The results showed that the formulation with MF59 adjuvant brought more stable immunogenicity against FMD and Clostridium perfringens type B, and the length of the immunogenicity period also increased significantly. Therefore, the combined vaccine (Clostridium perfringens + FMD) could play a major role invaccine industry as an alternative vaccine against Clostridium perfringens and FMD in livestock.

Field Evaluation of Novel Combination Vaccines Against Foot and Mouth Disease Virus and Clostridium perfringens Toxoid Using Different Immunization Protocols

Background: Foot and mouth disease (FMD) and enterotoxaemia are serious livestock diseases. The livestock industry has suffered heavy economic losses, especially in developing countries. Objectives: These two diseases can be effectively controlled and prevented via vaccination. To prepare multivalent vaccines, Clostridium perfringens (B, C, and D) toxoids were mixed with foot and mouth disease virus (FMDV; type O) along with adjuvants aluminum hydroxide and Montanide ISA206. Methods: According to the guidelines of the World Organization for Animal Health (OIE) and pharmacopeia, sheep were the target animals. Following the injection of vaccines, ELISA and virus neutralization test (VNT) antibody titers determined the effectiveness of the test vaccines. Results: The combination vaccine with ISA206 adjuvant resulted in anti-enterotoxaemia and anti-FMD antibody titers higher than OIE values and pharmacopeia standards. A statistically significant difference was found between the combination vaccine groups with and without Montanide ISA206 adjuvant for anti-enterotoxaemia antibody titers after the second vaccination (P < 0.05). In contrast, the mean VNT antibody titer of the combined vaccine against serotype O with ISA206 adjuvant was significantly higher than that of other FMD vaccine groups (P < 0.05). Moreover, all vaccinated groups (A, B, C, D, E, Fand G) displayed significantly higher than the negative control group (P < 0.05). Conclusions: This study showed that enterotoxaemia-FMD combined vaccines could replace traditional livestock vaccines on an industrial scale.

Antigenic relationship of West Nile strains by titre ratios calculated from cross-neutralization test results

The antigenic relationship of ten South African West Nile isolates, the South African prototype virus H442, the Egyptian strain EG101 and the Indian strain G2266 were compared using titre ratios. The titre ratios or 'R' values were calculated from heterologous and homologous neutralization titres and expressed as a percentage. Substantial antigenic differences were demonstrated between the South African prototype strain and the majority of the recently obtained South African isolates, seven of which were fairly closely related and possibly form a distinct antigenic sub-set. The recent isolates also differed from the Egyptian and Indian West Nile isolates. The heterologous results between the South African West Nile strains and the Indian strain G2266 suggest that prior infection with an Indian West Nile virus would give poor protection against the South African viruses, whereas the reverse would not be so.

Antigenic variation in foot-and-mouth disease: studies based on the virus neutralization reaction

The neutralization reaction is the most appropriate in vitro reference test system for assessing intratypic antigenic variation as it involves the antigenic determinants responsible for virus strain specificity and evoking protective antibody. Antigenic relationships determined in different neutralization test systems were independent of the system used and were assumed to truly reflect antigenic variation. The two-dimensional microneutralization test was found to be appropriate for foot and mouth disease (FMD) virus strain differentiation. To minimize test to test variation, comparisons are performed as matched pairs. The pooled variance of the test system is used to assess the significance of the relationships obtained. Antisera from convalescent animals were less specific than those from vaccinates. Serum quality seemed less critical for the virus neutralization than the complement fixation reaction. A system for FMD virus strain differentiation based on the use of the virus neutralization reaction taking into account the statistical and biological significance of observed r values is recommended.

Microneutralization tests for serological typing and subtyping of foot-and-mouth disease virus strains

A microneutralization test for serotyping of FMD viruses is described. It is based on earlier observations by Booth, Rweyemamu & Pay (1978) that dose-response relationships in quantal microneutralizations often deviated from linearity. The typing test described therefore utilizes undiluted virus preparations. In about 90% of samples a positive typing was obtained in contrast with about 50% for the complement fixation test. The test was also found to be susceptible to minimal quantities of heterotypic viral contamination. For strain differentiation the microneutralization test was carried out as a checkerboard test. When compared with the complement fixation test it was found to be more specific. The necessity to utilize virus-neutralization test systems for comparing FMD virus strains particularly for the purpose of vaccine selection is emphasized. The two dimensional microneutralization test has been applied to a study of comparing FMDV vaccine strains for Europe, South America, the Middle East and East Africa.