title: [Comparison of 2 in vitro methods of titration of antibodies neutralizing the classic swine plague virus].
abstract: Swine fever virus neutralization have been studied by the following method: variable plaque forming units numbers are mixed with a predetermined serum dilution. Infectivity is measured before (VO) and after (Vr) neutralization reaction. Neutralization index (N.I. = logVo/V) represent the difference between the two titers. It had been demonstrated that mass law is a good approximation to describe swine fever virus neutralization. So the most useful form in which to express the relation between N.I. and dilution logarithm (log D) is NI = NIo--K log D (I) where K is the constante corresponding to the slope of neutralization curve. A sligh K variation is observed according to immunoglobulin classes sharing antibody activity. Average K value is equal to 3. NIO is the NI obtained when extrapolating the curve to log D = o. These results have permitted to compare the two seroneutralization methods commonly used: "constant serum" method and "variable serum" method (determination of serum dilution inhibiting 50% of infectivity: D50). From formula (I) the following relation can be obtained: see formular. Theoretical and experimental log D50 values were appromaximatively the same (difference inferior or equal to 0.3). So D50 can be calculated by both methods.
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis*; D006691:Classical Swine Fever / Q000276:immunology / Q000382:microbiology*; D007106:Immune Sera; D009500:Neutralization Tests / Q000379:methods* / Q000662:veterinary; D012328:RNA Viruses / Q000276:immunology*; D013552:Swine / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D007106:Immune Sera
vernacular_title: Comparaison de deux méthodes in vitro de titrage des anticorps neutralisant le virus de la peste porcine classique