M. Harmsen

Neutralizing and non-neutralizing monoclonal antibodies to the E2 glycoprotein of Semliki Forest virus can protect mice from lethal encephalitis.

Two monoclonal antibodies (UM 4.2 and UM 5.1) directed against the glycoprotein E2 of Semliki Forest virus (SFV) are described; both belong to the IgG2a isotype but are of different idiotype. Analysis employing isoelectric focusing resulted in different focusing patterns for both monoclonals (UM 4.2, pI 8; UM 5.1, pI 7.2). They further differed in their ability to neutralize virus. The UM 4.2 antibodies were inactive in neutralization, while the UM 5.1 antibodies exceeded conventional mouse hyperimmune serum in this respect. Both monoclonal antibodies, however, were able to protect mice passively from a lethal infection with SFV. Based on the amount of protein, the UM 5.1 antibodies were 100-fold more effective than the UM 4.2 antibodies in mouse protection tests.

Antigenic differences between virulent and avirulent strains of Semliki Forest viruses detected with monoclonal antibodies: brief report

SummaryEleven monoclonal antibodies (MAs) reacted strongly in an enzyme immunoassay with virulent Semliki Forest virus (SFV) replicating in L cell monolayers. Three MAs showed a considerably diminished reaction with an avirulent strain of SFV both in enzyme immunoassays and plaque reduction tests.

Prophylaxis and therapy of virulent encephalomyocarditis virus infection in mice by monoclonal antibodies

SummaryTwo encephalomyocarditis virus (EMCV) neutralizing monoclonal antibodies (MAs), recognizing different determinants on EMCV, were both able to protect mice prophylactically and therapeutically against a lethal dose of EMCV.

Delayed type hypersensitivity against Semliki forest virus in mice: local transfer of delayed type hypersensitivity with thioglycollate-induced peritoneal exudate cells

In mice, a strong delayed type hypersensitivity (DH) without detectable neutralizing antibodies in serum could be obtained after intracutaneous injection of inactivated Semliki Forest virus (SFV) mixed with the adjuvant dimethyl dioctadecyl ammonium bromide (DDA). Thioglycollate-induced peritoneal exudate cells (PEC) from these mice were highly effective in passive transfer of DH against SFV locally in footpads of naive recipient mice. DH reactions were measured with a footpad swelling test. By contrast, either immune PEC from nonstimulated peritoneal cavities or thioglycollate-induced PEC from mice which had developed neutralizing antibodies were unable to transfer DH passively.

Blocking by anti-idiotypic antibodies of monoclonal antibody mediated protection in mice against encephalomyocarditis virus induced diabetes and lethal disease

SummaryMonoclonal antibodies (MA) UM 21.1 and UM 21.2 protect mice against encephalomyocarditis virus (D-variant) induced diabetes and lethal disease. MA-mediated protection in vivo as well as neutralization in vitro could be specifically blocked by anti-idiotypic antibodies.

Modulation of adjuvant-enhanced delayed-type hypersensitivity by the interferon inducers poly I:C and Newcastle disease virus.

The modulation by the interferon (IFN) inducers poly I:C and Newcastle disease virus (NDV) of the effector phase of adjuvant-enhanced delayed-type hypersensitivity (DH) was studied in mice. A strongly enhanced DH was induced in mice to ultraviolet (UV) light inactivated Semliki forest virus (SFV) by the use of the adjuvant dimethyldioctadecylammonium bromide. At day 6 after intracutaneous immunization, DH was elicited with SFV and measured 24 and 48 h later as increase in footpad thickness (footpad swelling test). Systemic, intravenous administration of either poly I:C, UV-inactivated NDV, or NDV-induced IFN prior to elicitation of DH with antigen resulted in a temporarily suppressed DH reaction. Both the poor swelling at 3 h and strong swelling at 24 h were suppressed, while the swelling at 48 h was enhanced. The model described provides a sensitive in vivo method to study modulating effects of drugs and microbial agents on the effector phase of DH.

Potentiation of the Cellular Immune Response by Adjuvants: A Limited Role for Adjuvant Induced Interferon

Adjuvants differ in capacity to induce interferon (IFN). As a consequence IFN induction by adjuvants may influence their effectiveness in enhancement of delayed type hypersensitivity (DH) reactions. In this study, the lipophilic amine dimethyl dioctadecyl ammonium bromide (DDA), the synthetic double-stranded polynucleotide polyinosinic polycytidylic acid (poly I:C), liposomes and the polyols L 101 and L 121 were compared in BALB/c mice as inducers of IFN and also as adjuvants for DH to both lysozyme and inactivated Semliki Forest virus (SFV). The antigens were injected intracutaneously, alone or mixed with adjuvant. At day 6 after the immunization, DH was elicited and measured 24 h later as increase in footpad thickness. Negatively charged liposomes and polyol L 121 were unable to enhance DH to SFV and also lack the capacity to induce IFN. Polyol L 101 induced low levels of IFN and showed only slight adjuvanticity for DH to SFV. In contrast, DDA, a moderate IFN inducer, was shown to be a very effective adjuvant for induction of DH against both lysozyme and SFV. The excellent IFN inducer, poly I:C, at the tested dose range (0.03-3.0 mg/kg), displayed only a relatively weak adjuvant activity. But low doses of poly I:C (0.03 and 0.1 mg/kg) showed still adjuvanticity in contrast to equal doses of DDA. This might be related to sufficient induction of IFN by low doses of poly I:C but not by DDA. The discrepancy observed in the relation between IFN induction and a maximal DH induction suggests that IFN is not the only factor which enhances the effectiveness of adjuvants in induction of DH.(ABSTRACT TRUNCATED AT 250 WORDS)

Blocking by anti-idiotypic antibodies of monoclonal antibody-mediated protection against lethal Semliki Forest virus in mice.

Semliki Forest virus‐(SFV) neutralizing monoclonal antibodies (MoAbs), produced after fusion of spleen cells from BALB/c mice and myeloma cell line P3‐X63‐AG8.653 or SP2/0, were used for anti‐idiotypic immunization of female BALB/c mice. Two intracutaneous immunizations (2 × 40 μg per animal), 3 weeks apart, with keyhole limpet haemocyanin‐conjugated MoAbs mixed with the saponin Quil A were sufficient to induce high levels of anti‐idiotypic antibodies in the circulation of these mice with the capacity to block specifically in vitro MoAb‐mediated virus neutralization. Anti‐idiotypic antibodies against SFV‐neutralizing MoAbs, either passively transferred or actively acquired by immunization, are also able to abrogate (specifically) passive immunity, mediated by critical protective doses of MoAb, in mice against infection with a lethal strain of SFV. Furthermore we confirmed by intervention with anti‐idiotypic serum in vivo that an SFV‐ neutralizing MoAb exerts its greatest protective effect during the first 2 days of infection.

Detection by a solid phase independent enzyme immunoassay of monoclonal anti-idiotypic antibodies against monoclonal antibodies neutralizing Semliki Forest virus and encephalomyocarditis virus

Neutralization inhibition enzyme immunoassay (NI-EIA) was evaluated for its usefulness to detect monoclonal anti-idiotypic antibodies (ab2mAbs) against idiotypic monoclonal antibodies (ab1mAbs) neutralizing either Semliki Forest virus (SFV) or encephalomyocarditis virus (EMCV). Purified ab1mAbs were coupled to keyhole limpet hemocyanin (KLH) mixed with the adjuvant Quil A and then injected intracutaneously into homologous BALB/c mice. Successful fusions were performed 5, 6 and 7 days after intracutaneous booster immunizations of these mice. Ab2mAbs in hybridoma supernatant fluids were detected by their capacity to block virus neutralization by ab1mAbs in NI-EIA. Two stable ab2mAb producing hybridomas were obtained against SFV neutralizing mAb UM 1.13, and twelve against EMCV neutralizing mAb UM 21.1.

Detection of a shared idiotope on two encephalomyocarditis virus neutralizing monoclonal antibodies by neutralization inhibition enzyme immunoassay

Idiotypic cross-reactivity between encephalomyocarditis virus (EMCV) neutralizing monoclonal antibodies UM 21.1 (IgG2b) and UM 21.3 (IgG2a) was detected by neutralization inhibition enzyme immunoassay using polyclonal and monoclonal anti-idiotypic antibodies. One strongly cross-reactive anti-idiotypic monoclonal antibody, designated 21.1A5 (IgG2b), might recognize a recurrent idiotope on EMCV neutralizing antibodies but it did not induce EMCV neutralizing anti-anti-idiotypic antibodies in homologous BALB/c mice.