Isolation of porcine, canine and feline IgG by affinity chromatography using protein A

Generation of a canine anti-EGFR (ErbB-1) antibody for passive immunotherapy in dog cancer patients

Passive immunotherapy with monoclonal antibodies represents a cornerstone of human anticancer therapies, but has not been established in veterinary medicine yet. As the tumor-associated antigen EGFR (ErbB-1) is highly conserved between humans and dogs, and considering the effectiveness of the anti-EGFR antibody cetuximab in human clinical oncology, we present here a "caninized" version of this antibody, can225IgG, for comparative oncology studies. Variable region genes of 225, the murine precursor of cetuximab, were fused with canine constant heavy gamma and kappa chain genes, respectively, and transfected into Chinese hamster ovary (CHO) DUKX-B11 cells. Of note, 480 clones were screened and the best clones were selected according to productivity and highest specificity in EGFR-coated ELISA. Upon purification with Protein G, the recombinant cetuximab-like canine IgG was tested for integrity, correct assembly, and functionality. Specific binding to the surface of EGFR-overexpressing cells was assessed by flow cytometry and immunofluorescence; moreover, binding to canine mammary tissue was demonstrated by immunohistochemistry. In cell viability and proliferation assays, incubation with can225IgG led to significant tumor cell growth inhibition. Moreover, this antibody mediated significant tumor cell killing via phagocytosis in vitro. We thus present here, for the first time, the generation of a canine IgG antibody and its hypothetical structure. On the basis of its cetuximab-like binding site, on the one hand, and the expression of a 91% homologous EGFR molecule in canine cancer, on the other hand, this antibody may be a promising research compound to establish passive immunotherapy in dog patients with cancer.

Antibodies against Gag are diagnostic markers for feline foamy virus infections while Env and Bet reactivity is undetectable in a substantial fraction of infected cats

Spumaretroviruses or foamy viruses constitute a distinct subfamily of retroviruses. The biology of foamy viruses within the authentic host, their mode of transmission, and disease potential in the authentic host or after zoonotic transmission into human or other species are almost unknown. Using feline foamy virus (FFV) as model system, we established modular enzyme-linked immunosorbent assays (ELISA) suited to determine feline IgG and IgM antibody responses against structural and non-structural FFV proteins. We validated the ELISAs with standard reference sera. In 99 cats admitted to a Swiss veterinary hospital, overall FFV Gag antibody prevalence was 36%, reactivity against Env and the non-structural protein Bet each was about 25%, and 19% of the sera were directed against all three FFV antigens. With one exception, all Bet- and/or Env-positive sera were also positive for Gag. In this small epidemiological pilot study, FFV antibodies were not significantly associated with clinical disease.

Immunogenicity of an E1-deleted recombinant human adenovirus against rabies by different routes of administration

The immunogenic properties of an E1-deleted, human adenovirus type 5 (Ad5) vaccine virus with activity against rabies were examined in mice, foxes and dogs using different routes of administration. NMRI mice received 10(5.8), 10(5.3), 10(4.3), 10(3.3) and 10(2.3) TCID(50) by peroral or intramuscular (i.m.) administration. Furthermore, six mice received 10(5.8) TCID(50) intracerebrally (i.c.). The construct elicited marked seroconversion in mice after oral administration. Immunoreactivity in mice was even more pronounced i.m. and i.c. After direct oral administration (10(8.0) TCID(50)) in foxes, six of eight animals developed rabies virus-neutralizing antibodies (VNA). All foxes immunized by direct injection (10(7.7) TCID(50)) in the membrane of the jejunum were shown to seroconvert. Pre-existing immunity against canine adenovirus did not hinder the development of rabies VNA after oral application of the construct (10(8.0) TCID(50)). Fox cubs (24-29 days old) born from rabies-immune vixens were shown to develop very high levels of rabies VNA after i.m. administration (10(8.0) TCID(50)), indicating that the immunogenicity of the construct could surpass maternally transferred immunity. In dogs, the construct (10(8.0) TCID(50)) induced a very strong immune response after i.m. administration. However, no immune response was detectable in dogs after direct oral administration (10(8.3) TCID(50)) or after endoscopic deposition in the smaller intestine (10(8.0) TCID(50)). Hence, it must be concluded that the construct is not suitable for oral vaccination of dogs against rabies.