Subject(s)
Immunoassay/methods , Tetanus Toxoid/analysis , Animal Testing Alternatives/methods , Animals , Enzyme-Linked Immunosorbent Assay/methods , Guinea Pigs , Hemagglutination Tests/methods , In Vitro Techniques , Laboratories , Neutralization Tests/methods , Rabbits , Reproducibility of Results , Tetanus Antitoxin/blood , Tetanus Toxoid/pharmacologyABSTRACT
An interlaboratory validation study was carried out in seven laboratories to evaluate the suitability of in vitro serological assay systems for the assessment of the potency of tetanus toxoid in single and multicomponent vaccines for veterinary use. Nine commercial vaccines and one experimental tetanus toxoid preparation were selected for immunization purposes according to Method A of the European Pharmacopoeia. Levels of tetanus antibodies in guinea-pig and rabbit serum samples were estimated by indirect ELISA, toxin binding inhibition (ToBI) test, passive haemagglutination (HA) test and by the prescribed standard toxin neutralization (TN) test in mice. Estimates of potency obtained by in vitro tests and by TN test were in good agreement for the various vaccines tested and for antibody levels of individual serum samples in the range 2.6 IU/ml to 266 IU/ml. Significant (P < 0.05) intralaboratory variation occurred less frequently for ELISA and ToBI test than for HA test. The frequency of significant (P < 0.05) interlaboratory variation was acceptable for the ELISA and the ToBI test but greater variation was observed for the HA test. It is concluded that the ELISA and ToBI tests are suitable in vitro assay systems for assessing the potency of tetanus toxoid in batches of single and multicomponent vaccines for veterinary use. Rigid standardization of the HA test is essential before this test can be used for the same quality control purpose.
Subject(s)
Laboratories/standards , Tetanus Toxoid/standards , Veterinary Medicine/standards , Animals , Enzyme-Linked Immunosorbent Assay , Hemagglutination Tests , Mice , Neutralization Tests , Reproducibility of ResultsABSTRACT
The purpose of this study was to determine the susceptibility of various strains of Mycoplasma bovis, Mycoplasma dispar, and Ureaplasma diversum, which are prevalent causes of pneumonia in calves, to 16 antimicrobial agents in vitro. The MICs of the antimicrobial agents were determined by a serial broth dilution method for 16 field strains and the type strain of M. bovis, for 19 field strains and the type strain of M. dispar, and for 17 field strains of U. diversum. Final MICs for M. bovis and M. dispar were read after 7 days and final MICs for U. diversum after 1 to 2 days. All strains tested were susceptible to tylosin, kitasamycin, and tiamulin but were resistant to nifuroquine and streptomycin. Most strains of U. diversum were intermediately susceptible to oxytetracycline but fully susceptible to chlortetracycline; most strains of M. bovis and M. dispar, however, were resistant to both agents. Strains of M. dispar and U. diversum were susceptible to doxycycline and minocycline, but strains of M. bovis were only intermediately susceptible. Susceptibility or resistance to chloramphenicol, spiramycin, spectinomycin, lincomycin, or enrofloxacin depended on the species but was not equal for the three species. The type strains of M. bovis and M. dispar were more susceptible to various antimicrobial agents, including tetracyclines, than the field strains. This finding might indicate that M. bovis and M. dispar strains are becoming resistant to these agents. Antimicrobial agents that are effective in vitro against all three mycoplasma species can be considered for treating mycoplasma infections in pneumonic calves. Therefore, tylosin, kitasamycin, and tiamulin may be preferred over oxytetracycline and chlortetracycline.
