Monoclonal antibody analysis of neutralization and antibody-dependent enhancement of feline infectious peritonitis virus

J Virol. 1992 Nov;66(11):6695-705. doi: 10.1128/JVI.66.11.6695-6705.1992.


Fifty-four monoclonal antibodies (MAbs) to feline infectious peritonitis virus (FIPV) were characterized according to protein specificity, immunoglobulin subclass, virus neutralization, reactivity with different coronaviruses, and ability to induce antibody-dependent enhancement (ADE) of FIPV infection in vitro. The MAbs were found to be specific for one of three structural proteins of FIPV. A total of 47 MAbs were specific for the 205-kDa spike protein (S), 3 MAbs were specific for the 45-kDa nucleocapsid protein (N), and 4 MAbs were specific for the 26- to 28-kDa membrane protein (M). The S-specific MAbs showed various degrees of cross-reactivity with strains of FIPV, feline enteric coronavirus, canine coronavirus, and porcine transmissible gastroenteritis virus. Nineteen S-specific MAbs neutralized FIPV. A total of 15 of the neutralizing MAbs induced ADE, and all but 1 were of the immunoglobulin G2a subclass. The remaining four neutralizing MAbs that did not induce ADE were of the immunoglobulin G1 subclass. Two S-specific MAbs induced ADE but were nonneutralizing. None of the N- or M-specific MAbs was neutralizing or induced ADE. On the basis of the reactivity patterns of the MAbs with FIPV and related coronaviruses, it was concluded that there is a minimum of five neutralizing sites on S. In most instances, neutralizing MAbs were able to induce ADE, demonstrating a direct relationship between neutralization and enhancement. The difference in immunoglobulin subclass between neutralizing MAbs that induced ADE and those that did not induce ADE suggests that there may be a restriction in the immunoglobulin subclasses capable of mediating ADE.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Antibodies, Viral / immunology*
  • Antigens, Viral / immunology*
  • Capsid / immunology
  • Cats
  • Coronaviridae / immunology
  • Coronavirus, Feline / immunology*
  • Cross Reactions
  • Epitopes / immunology
  • Fluorescent Antibody Technique
  • Immunization*
  • Immunoglobulin G / classification
  • Models, Biological
  • Mutation
  • Neutralization Tests
  • Precipitin Tests
  • Viral Core Proteins / immunology
  • Viral Matrix Proteins / immunology
  • Viral Proteins / immunology
  • Viral Proteins / isolation & purification


  • Antibodies, Monoclonal
  • Antibodies, Viral
  • Antigens, Viral
  • Epitopes
  • Immunoglobulin G
  • Viral Core Proteins
  • Viral Matrix Proteins
  • Viral Proteins
  • spike protein S, Transmissible gastroenteritis virus