Characterization of monoclonal antibodies against feline infectious peritonitis virus type II and antigenic relationship between feline, porcine, and canine coronaviruses

Abstract

Seven monoclonal antibodies (MAbs) with neutralizing activity against feline infectious peritonitis virus (FIPV) strain 79-1149 (type II) were prepared. When the polypeptide specificity recognized by these monoclonal antibodies (MAbs) was investigated by Western immunoblotting, all of the MAbs reacted with peplomer glycoprotein (S) of the virus. By competitive binding assay these MAbs were found to recognize at least 3 different epitopes. The reactivity of these MAbs with 6 viruses classified as FIPV type I (UCD-1, UCD-2, UCD-3, UCD-4, NW-1, and Black), feline enteric coronavirus (FECV) type II strain 79-1683, canine coronavirus (CCV) strain 1-71, and transmissible gastroenteritis virus (TGEV) strains TO-163 and SH was examined by neutralization tests. All MAbs neutralized FECV strain 79-1683, CCV strain 1-71, and TGEV strains TO-163 and SH, while they did not neutralize the 6 FIPV type I viruses. Moreover, the MAb against TGEV strain TO-163, which has strong neutralizing activity against 7 TGEV viruses, neutralized CCV strain 1-71, FECV strain 79-1683, and FIPv strain 79-1146, but did not neutralize the 6 FIPV type I viruses. These results demonstrated that there are at least 3 epitopes involved in the neutralization of FIPV type II strain 79-1146, and that these epitopes are not present in FIPV type I viruses but are present in FECV strain 79-1683 which does not induce feline infectious peritonitis, TGEV strains TO-163 and SH, and CCV strain 1-71. These results suggest the presence of 2 serotypes of FIPV which can be clearly distinguished by the neutralization test using MAbs.

Antibody-Dependent Enhancement of Feline Infectious Peritonitis Virus Infection in Feline Alveolar Macrophages and Human Monocyte Cell Line U937 by Serum of Cats Experimentally or Naturally Infected with Feline Coronavirus.

“…Horzinek (The State University, Utrecht, the Netherlands) and Dr. N. C. Pedersen (University of California, Davis, U.S.A.), respectively. Strain 79-1146 was classified as type II FCoV, and strains KU-2 and UCD-1 were classified as type I FCoV [5,12].…”

“…The type II strains appeared to be more closely related to canine coronavirus (CCV) and transmissible gastroenteritis virus (TGEV), since immunodominant neutralization epitopes shared by the spike proteins of TGEV, CCV, and the type II FCoV strains seemed to be absent in the type I strains [12]. Recently, these findings were confirmed by sequence analysis.…”

“…However, the FIPV UCD-1 strain used in their study proliferates well in CrFK cells, and is antigenically similar to type II FCoVs, CCV and TGEV [4,21]. These properties are different from those of the original UCD-1 strain [12,23]. Recently, de Groot and Horzinek [5] indicated the possibility of virus stocks may have been interchanged.…”

Analysis of the mechanism of antibody-dependent enhancement of feline infectious peritonitis virus infection: aminopeptidase N is not important and a process of acidification of the endosome is necessary

“…FCoVs are classified into types I and II according to their S protein properties (Hohdatsu et al, 1991a;Motokawa et al, 1995Motokawa et al, , 1996. FCoVs are also classified into two biotypes based on differences in pathogenicity: feline enteric coronavirus (FECV) and FIPV.…”

Comparison of Serologic Techniques for the Detection of Antibodies against Feline Coronaviruses

“…On the basis of neutralization tests in vitro, FCoV can be distinguished into 2 serotypes, FCoV type I and FCoV type II. 17,18,24 In the field, serotype II accounts for only 20% to 30% of all FCoV infections. 16,27 Type I viruses represent the genuine FCoVs and grow poorly in cell culture.…”