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Inactivated-concentrated virus antigen for indirect complement fixation test of foot-and-mouth disease
Abstract:
To the culture fluids of BHK-21 cells infected with each of types O, A, and Asia 1 of foot-and-mouth disease virus was added acetylethyleneimine to 0.05% (v/v). The mixtures were incubated at 37 degrees C for 24 hours. To them were then added polyethylene glycol 6000 to 10% (w/v), and the mixtures concentrated to one-tenth of the initial volume. The resulting inactivated-concentrated virus antigens showed a complement fixation (CF) titer ranging from 12 to 24. The recovery rate of CF activity was 40 approximately 60%. This activity of each antigen was maintained at 4 degrees C or -70 degrees C for 6 months at least. Experimentally infected cattle were examined for the development of antibody by the aid of the indirect complement fixation (ICF) test with those antigens. As a result, ICF antibody began to be detected 3 approximately 5 days after inoculation. Its titer reached a maximum 10 approximately 14 days after inoculation and decreased gradually thereafter. It was detected even 232 days after inoculation. There was a tendency for the development of ICF antibody to be parallel with that of neutralizing antibody. It was suggested that ICF antibody might be type-specific. In conclusion, the antigens prepared had such high activity that they could be used for the determination of antibody by ICF. In addition, they were of great practical value because of their sufficient keeping quality and safety.
Insights
New inactivated-concentrated foot-and-mouth disease virus antigens were developed using acetylethyleneimine and polyethylene glycol. These safe and stable antigens are effective for detecting indirect complement fixation (ICF) antibodies in cattle.
Area of Science:
- Veterinary Virology
- Immunology
Background:
- Foot-and-mouth disease (FMD) poses a significant threat to livestock globally.
- Accurate diagnostic tools are crucial for FMD surveillance and control.
Purpose of the Study:
- To develop and characterize inactivated-concentrated antigens for FMD virus.
- To evaluate the efficacy of these antigens in detecting antibodies in experimentally infected cattle.
Main Methods:
- Inactivation of FMD virus (types O, A, Asia 1) using acetylethyleneimine.
- Concentration of viral antigens with polyethylene glycol 6000.
- Assessment of antigen stability and complement fixation (CF) titer.
- Evaluation of antibody response in cattle using indirect complement fixation (ICF) test.
Main Results:
- Inactivated-concentrated FMD virus antigens demonstrated high CF titers (12-24) with 40-60% recovery rate.
- Antigens remained stable for at least 6 months at 4°C or -70°C.
- ICF antibodies were detected in cattle 3-5 days post-inoculation, peaking at 10-14 days and persisting for over 232 days.
- ICF antibody development correlated with neutralizing antibody levels and appeared type-specific.
Conclusions:
- The prepared FMD virus antigens are highly active, stable, and safe for use in diagnostic assays.
- The ICF test using these antigens is a valuable tool for determining FMDV antibody levels in cattle.
- These antigens hold practical value for FMD surveillance and epidemiological studies.