Recombinant Bispecific Antibodies to the Human ErbB2 Receptor and Interferon-Beta

The development of and research into new therapies that can selectively and effectively destroy tumor cells that overexpress the ErbB2 receptor is apressing task. Recently, research into the use of type I interferons in the treatment of cancer has intensified. Cytokine therapy is aimed at activating the cells of the immune system to fight tumors, but it has drawbacks that limit its use because of a number of side effectsthe severity of which varies depending on the dosage and type of used cytokine. At the moment, a number of studies are being conducted regarding the use of IFNin oncology. The studies areaimed at mitigating the systemic action of this cytokine. The immunocytokine complex made of a bispecific antibody against the ErbB2 receptor and recombinant IFNdeveloped in this study underlies themechanism meant to avoid the systemic action of this cytokine. Part of this study focuses on the development of full-length antibodies that bind to the ErbB2 receptor on the one hand, and bind and neutralize IFN, on the other hand, which allows us to consider the antibodies as a means of cytokine delivery to tumor cells.

Recombinant Bispecific Antibodies to the Human ErbB2 Receptor and Interferon-Beta

The development of and research into new therapies that can selectively and effectively destroy tumor cells that overexpress the ErbB2 receptor is a pressing task. Recently, research into the use of type I interferons in the treatment of cancer has intensified. Cytokine therapy is aimed at activating the cells of the immune system to fight tumors, but it has drawbacks that limit its use because of a number of side effects the severity of which varies depending on the dosage and type of used cytokine. At the moment, a number of studies are being conducted regarding the use of IFNβ in oncology. The studies are aimed at mitigating the systemic action of this cytokine. The immunocytokine complex made of a bispecific antibody against the ErbB2 receptor and recombinant IFNβ developed in this study underlies the mechanism meant to avoid the systemic action of this cytokine. Part of this study focuses on the development of full-length antibodies that bind to the ErbB2 receptor on the one hand, and bind and neutralize IFNβ, on the other hand, which allows us to consider the antibodies as a means of cytokine delivery to tumor cells.

The Generation of the Human mAb RabD4 Specific to the Rabies Virus Glycoprotein and Characterization Thereof

We generated a novel human neutralizing human mAb RabD4 against rabies virus glycoprotein using in vitro stimulation of human peripheral B cells produced by immunized donor. The human mAb RabD4 showed a high antigen-binding activity and virus-neutralizing activity in the FAVN test with the CVS-11 rabies virus.

Structure of the Anti-C60 Fullerene Antibody Fab Fragment: Structural Determinants of Fullerene Binding

The structure of the anti-C60 fullerene antibody Fab fragment (FabC60) was solved by X-ray crystallography. The computer-aided docking of C60 into the antigen-binding pocket of FabC60 showed that binding of C60 to FabC60 is governed by the enthalpy and entropy; namely, by - stacking interactions with aromatic residues of the antigen-binding site and reduction of the solvent-accessible area of the hydrophobic surface of C60. A fragment of the mobile CDR H3 loop located on the surface of FabC60 interferes with C60 binding in the antigen-binding site, thereby resulting in low antibody affinity for C60. The structure of apo-FabC60 has been deposited with pdbid 6H3H.

Structure of the Anti-C60 Fullerene Antibody Fab Fragment: Structural Determinants of Fullerene Binding

The structure of the anti-C₆₀ fullerene antibody Fab fragment (FabC₆₀) was solved by X-ray crystallography. The computer-aided docking of C₆₀ into the antigen-binding pocket of FabC₆₀ showed that binding of C₆₀ to FabC₆₀ is governed by the enthalpy and entropy; namely, by π-π stacking interactions with aromatic residues of the antigen-binding site and reduction of the solvent-accessible area of the hydrophobic surface of C₆₀. A fragment of the mobile CDR H3 loop located on the surface of FabC₆₀ interferes with C₆₀ binding in the antigen-binding site, thereby resulting in low antibody affinity for C₆₀. The structure of apo-FabC₆₀ has been deposited with pdbid 6H3H.

[In vitro Antiviral Activity of Recombinant Antibodies of IgG and IgA Isotypes to Hemagglutinin of the Influenza A Virus]

Seasonal and highly infectious strains of the influenza A and influenza B viruses cause millions of cases of severe complications in elderly people, children, and patients with immune diseases each year. Immunoglobulin A (IgA), which is an active component of humoral immunity, can prevent the spread of the virus in the upper respiratory tract. The preparation and study of the properties of recombinant virus-specific IgA could be an important approach to finding new means of preventing and treating influenza. Based on CHO DG44 cells, we developed stable monoclonal cell lines that produce monomeric and dimeric antibodies FI6-IgA1 and FI6-IgA2m1 to hemagglutinin (HA) of the influenza A virus. When studying the productivity, growth, and stability of the obtained clones, we found that the dimeric form of antibodies of IgA1 isotype is superior to other forms. The dimeric form of IgA antibodies plays a key role in mucosal immunity. Recognizing the prospects of using dimeric IgA as prophylactic and therapeutic mucosal drugs for viral infections, we studied their virus-neutralizing and antiviral activities on MDCK cell culture and compared them with the antibodies of the IgG1 isotype. This study presents the data on antiviral and virus-neutralizing activities of the FI6-IgA1 dimers to seasonal and highly infectious strains of influenza A virus.

The Development and Study of Recombinant Immunoglobulin A to Hemagglutinins of the Influenza Virus

We obtained recombinant variants of human antibody FI6 broadly specific to hemagglutinins of the influenza A virus. On the basis of a bi-promoter (CMV, hEF1-HTLV) vector, we developed genetic constructs for the expression of the heavy and light chains of the immunoglobulins of IgA1-, IgA2m1-, and IgG-isotypes. Following transfection and selection, stable Chinese hamster ovary (CHO) cell lines were produced. The antibodies of IgA1-, IgA2m1-, and IgG-isotypes were purified from culture media. We performed an immunochemical characterization and studied their interactions with influenza A strains of the H1N1- and H3N2-subtypes. It was shown that recombinant FI6 variants of the IgA-isotype retain the properties of the parental IgG antibody to demonstrate specificity to all the strains tested. The strongest binding was observed for the H1N1 subtype, which belongs to hemagglutinins of phylogenetic group I.

The Development and Study of Recombinant Immunoglobulin A to Hemagglutinins of the Influenza Virus

We obtained recombinant variants of human antibody FI6 broadly specific to hemagglutinins of the influenza A virus. On the basis of a bi-promoter (CMV, hEF1-HTLV) vector, we developed genetic constructs for the expression of the heavy and light chains of the immunoglobulins of IgA1-, IgA2m1-, and IgG-isotypes. Following transfection and selection, stable Chinese hamster ovary (CHO) cell lines were produced. The antibodies of IgA1-, IgA2m1-, and IgG-isotypes were purified from culture media. We performed an immunochemical characterization and studied their interactions with influenza A strains of the H1N1- and H3N2-subtypes. It was shown that recombinant FI6 variants of the IgA-isotype retain the properties of the parental IgG antibody to demonstrate specificity to all the strains tested. The strongest binding was observed for the H1N1 subtype, which belongs to hemagglutinins of phylogenetic group I.

The Development and Inmmunochemical Properties of the Dimer of Immunoglobulin A Specific to the Influenza Virus A Hemagglutinin

We obtained dimeric forms of IgA1- and IgA2m1-isotypes of FI6 antibody broadly specific to hemagglutinins of different subtypes of influenza A virus. It was shown that the dimers of IgA1 isotype are characterized by a higher antigen-binding activity compared to the IgA2m1 dimers. The affinity of IgA1 dimers to the strains of the H1N1 subtype is higher than that of the H3N2 subtype, which correlates with the properties of the parental human FI6 antibody.

Recombinant Antibodies to the Ebola Virus Glycoprotein

Currently, there are no approved therapies for targeted prevention and treatment of Ebola hemorrhagic fever. In the present work, we describe the development of a eukaryotic expression system for the production of three full-length chimeric antibodies (IgG1-kappa isotypes) GPE118, GPE325, and GPE534 to the recombinant glycoprotein of the Ebola virus (EBOV GP), which is a key factor in the pathogenicity of the disease. The immunochemical properties of the obtained antibodies were studied by immunoblotting and indirect, direct, and competitive ELISA using the recombinant EBOV proteins rGPdTM, NP, and VP40. The authenticity of the antibodies and the absence of cross-specificity with respect to the structural proteins NP and VP40 of the Ebola virus were proved. The epitope specificity of the resulting recombinant antibodies was studied using commercial neutralizing antibodies against the viral glycoprotein. The recombinant antibodies GPE118, GPE325, and GPE534 were shown to recognize glycoprotein epitopes that coincide or overlap with the epitopes of three well-studied neutralizing anti-Ebola virus antibodies.

Recombinant Antibodies to the Ebola Virus Glycoprotein

Currently, there are no approved therapies for targeted prevention and treatment of Ebola hemorrhagic fever. In the present work, we describe the development of a eukaryotic expression system for the production of three full-length chimeric antibodies (IgG1-kappa isotypes) GPE118, GPE325, and GPE534 to the recombinant glycoprotein of the Ebola virus (EBOV GP), which is a key factor in the pathogenicity of the disease. The immunochemical properties of the obtained antibodies were studied by immunoblotting and indirect, direct, and competitive ELISA using the recombinant EBOV proteins rGPdTM, NP, and VP40. The authenticity of the antibodies and the absence of cross-specificity with respect to the structural proteins NP and VP40 of the Ebola virus were proved. The epitope specificity of the resulting recombinant antibodies was studied using commercial neutralizing antibodies against the viral glycoprotein. The recombinant antibodies GPE118, GPE325, and GPE534 were shown to recognize glycoprotein epitopes that coincide or overlap with the epitopes of three well-studied neutralizing anti-Ebola virus antibodies.

New monoclonal antibodies to the Ebola virus glycoprotein: Identification and analysis of the amino acid sequence of the variable domains

We determined the nucleotide and amino acid sequences of variable domains of three new monoclonal antibodies to the glycoprotein of Ebola virus capsid. The framework and hypervariable regions of immunoglobulin heavy and light chains were identified. The primary structures were confirmed using massspectrometry analysis. Immunoglobulin database search showed the uniqueness of the sequences obtained.

[Neutralizing Monoclonal and Chimeric Antibodies to Human IFN-γ]

Autoiminune disorders are chronic diseases characterized by abnormal immune response directed against self-antigens that leads to tissue damage and violation of its normal functioning. Such diseases often result in disability or even death of patients. Nowadays a number of monoclonal antibodies to pro-inflammatory cytokines and their receptors are successfully used for the targeted treatment of autoimmune diseases. One of the perspective targets in autoimmune disease therapy is interferon gamma, a key cytokine in Th1 cells differentiation, activation of macrophages, and inflammation. In the present work, 5 monoclonal antibodies to human IFN-γ were obtained. For the development of potential therapeutic agent, we have performed neutralizing activity and affinity analysis of the antibodies. Based on the data obtained, the monoclonal antibody F1 was selected. This antibody has a dissociation constant 1.7 x 10(-9) M and IC90 = 8.9 ± 2.0 nM measured upon antibody inhibition of the IFN-γ-induced HLA-DR expression on the surface of U937 cells. We have constructed a bicistronic vector for the production of recombinant chimeric Fab fragment F1 chim in E. coli cells. The recombinant chimeric Fab fragment Fl chim neutralizes IFN-γ activity in vitro and has a dissociation constant 1.8 x 10(-9) M.

Application of gold nanoparticles produced by laser ablation for immunochromatographic assay labeling

Nanodispersed gold is widely used as a marker in different analytical systems. For such purposes, it is usually obtained by the reduction of salts. This work studied the potential analytical applications of nanodispersed gold obtained by laser ablation because gold produced with this method has no chemical coating. The nanoparticles produced were characterized by transmission electron microscopy and spectrophotometry. The average size of the particles was 24.5 nm. Concentration dependences of antibody immobilization on ablative gold were obtained. With the use of antibody-conjugated nanoparticles, an immunochromatographic system was constructed for the detection of zearalenone mycotoxin. This immunoassay was characterized by a detection limit of 0.1 ng/ml antigen with an assay duration of only 15 min, which is on par with current test systems comprising nanodispersed gold obtained by chemical reduction. The simplicity of ablative dispersing makes this a prospective method for the labeling of various antibodies for analytical use.

[Development of an Immunochromatographic Test System for the Detection of Helicobacter pylori Antigens]

A test system based on immunochromatography in the sandwich format and intended for express detection of Helicobacter pylori antigens has been developed. Contact of a sample with a test strip coated with immunochemical reagents triggers the movement of the liquid along the membrane components of the test strip, immunochemical interactions, and the formation of detection zones stained by gold nanoparticles. The concentration and kinetic dependences of the immunochemical interactions have been characterized. The reagent and membrane composition of the test system has been selected to provide a minimal detection limit. The detection of H. pylori cell wall antigens at concentrations as low as 0.3 μg/mL in aqueous solution and a suspension of a clinical sample of feces has been demonstrated; the assay duration was 10 minutes. Staining enhancement by the addition of silver salts allowed for a further reduction of the detection limit to 0.03 μg/mL. The developed test system can be used for field diagnostics.

[Development of ELISA on the basis of monoclonal antibodies for detecting specific activity of the vaccine against hemorrhagic fever with renal syndrome]

The monoclonal antibodies to Puumala, Dobrava, Hantaan, and Seoul hantaviruses were obtained using mice. The viruses were known to cause HFRS, and two variants of ELISA were designed. First, Hanta-PUU variant, was constructed using monoclonal antibodies to Puumala virus envelope glycoprotein (G(N):G(C)) for detecting only Puumala virus antigen. The second, Hanta-N variant, was constructed using monoclonal antibodies to Dobrava and Puumala nucleocapsid proteins for detecting four above mentioned hantaviruses. Both Hanta-PUU and Hanta-N assays were reliable in detecting specific hantavirus antigens and the immunogenecity of hantavirus vaccines.

Conformational Differences between Active Angiotensins and Their Inactive Precursors

The peptide conformation in the context of a protein polypeptide chain is influenced by proximal amino acid residues. However, the mechanisms of this interference remain poorly understood. We studied the conformation of angiotensins 1, 2 and 3, which are produced naturally in a sequential fashion from a precursor protein angiotensinogen and contain an identical peptide core structure. Using the example of angiotensins 1, 2 and 3, it was shown that similar amino acid sequences may have significant conformational differences in various molecules. In order to assess the conformational changes, we developed a panel of high-affinity mouse monoclonal antibodies against angiotensins 1, 2 and 3 and studied their cross-reactivity in indirect and competitive ELISAs. It was found that the conformations of inactive angiotensin1 and the corresponding fragment of angiotensinogen are similar; the same is true for the conformations of active angiotensins 2 and 3, whereas the conformations of homologous fragments in the active and inactive angiotensins differ significantly.

[Heat-shock protein enhances immunogenicity of E7 oncoprotein of human papillomavirus included in chimeric construction (E7 HPV-HSP70)]

AIM

To study the effect of chimeric E7 protein of human papillomavirus type 18 on activation of adaptive immunity in absence of adjuvant.

MATERIALS AND METHODS

Chimeric protein was genetically engineered and represents the protein molecule consisting of full-size E7 oncoprotein and heat-shock protein 70 (HSP70) of Mycobacterium tuberculosis in one polypeptide chain. Antibody titers as well as isotypes and subisotypes of immunoglobulins were measured by ELISA in sera of immunized animals.

RESULTS

It was shown that studied construction E7 (HPV-18)-HSP70 significantly increases titers of antibodies to E7 protein of HPV type 18 and have cross-reactive antigenic activity with E7 protein of HPV type 16. Immunization with chimeric protein resulted in increase of IgG1 and IgG2b levels and decrease of IgG2a and IgM levels.

CONCLUSION

. Oncoprotein E7 included in chimeric construction with HSP70 could be used for further studies on development of therapeutic vaccine for treatment of cervical cancer and precancerous lesions. Skew of immune response to Th2 type after intraperitoneal administration of the studied construction points to necessity for control of immunity during such studies.

[Atomic force microscopy detection of serological markers of viral hepatites B and C]

The aim of the study was to demonstrate the possibility of detection of serological markers, containing the hepatitis B surface antigen (HBsAg) and hepatitis C virus core-antigen (HCVcoreAg) in human serum, by use of a new atomic force microscopy (AFM)-based nanotechnological approach. In this study, the immobilization on AFM-chip of antibodies against the hepatitis B virus surface antigen (anti-HBsAg) as well as the antibodies against the hepatitis C virus core antigen (anti-HCVcoreAg) was performed. It was shown that such approach enables to detect: HBsAg, HCVcoreAg and the viral fragments containing these antigens in the serum. Comparative analysis of detection of HBsAg- and HCVcoreAg-containing particles by use of the AFM method vs. traditional methods (ELISA, PCR) has demonstrated the 75% coincidence of results between the AFM and the latter two methods.

[Effect of recombinant heat-shock protein (rHSP70) of Mycobacterium tuberculosis on immunogenicity of Haemophilus influenzae type B capsular polysaccharide]

AIM

To study effect of recombinant heat-shock protein (rHSP70) of Mycobacterium tuberculosis on immunogenicity of Haemophilus influenzae type b capsular polysaccharide (CPSHib).

MATERIALS AND METHODS

Capsular polysaccharide was obtained by precipitation with cetavlon, antibody titers and Toll-like receptors (TLRs) were detected by enzyme immunoassay and flow cytometry respectively.

RESULTS

rHSP70 modified immune response to chemically conjugated and unconjugated CPSHib. rHSP70 enhanced expression of TLRs 2, 4, 9 on mice splenocytes; increased levels of CD3+, CD8+, NK, CD3/NK (NKT) lymphocytes. Levels of CD4+, CD25+ (markers of early activation of T-helpers) as well as MHC class II molecules were increased that could be appraised as a shift from T-independent to T-dependent immune response. Difference in antibody titers after 2- or 3-dose immunization of mice with 5 mcg/dose of CPSHib in mixture or conjugated with rHSP70 was not revealed. Level of antibodies to rHSP70 in serum samples of mice immunized with CPSHib conjugated with rHSP70 was 6.55 - 8.4 times higher compared to unimmunized animals. Antibodies, which have common antigenic epitopes to human organs and tissues, were not detected.

CONCLUSION

rHSP70 modifies immune response to CPSHib.

[Assessment of protective effect of heat shock protein-lypopolysaccharide of Salmonella typhimurium recombinant construction in mice]

AIM

To study protective activity of recombinant construction of heat-shock protein with lypopolysaccharide (rcHSP-LPS) as well as its variants (with destroyed protein or bounded LPS) against Salmonella typhimurium. It was also planned to study the ability of rcHSP-LPS to interact with toll-like receptors (TLRs) expressed on continuous cell lines.

MATERIALS AND METHODS

One of the following preparations was administered to outbred mice: rcHSP-LPS; rcHSP-LPS treated by polymyxin B (PMB) for bounding of LPS - rc(HSP-LPS)PMB; rcHSP-LPS in which protein was treated by boiling during 30 min--rc (HSP-LPS)B; LPS (E. coli K-235); polymyxin B (PMB). Twenty-four hours after single or last administration of rcHSP-LPS, each mice was intraperitoneally inoculated with 63 LD50 of S. typhimurium 415 contained in 0.5 ml of physiologic solution. Antibody titer to LPS of Salmonella typhimurium was measured by immunoenzyme assay.

RESULTS

It was demonstrated that rcHSP-LPS administered 24 hours before inoculation induced resistance to S. typhimurium infection. Protection formed after 3 injections of rcHSP-LPS with 10 mcg in each or single injection with 100 mcg/mouse. Forty to eighty percent of immunized mice survived after challenge while 90% of control animals died. Destroy of the HSP by boiling of the construction led to loss of protective effect. Bounding of LPS by PMB did not lead to loss of protective properties of the construction but they expressed only after its multiple administration with 10 mcg per mouse. LPS of E. coli in dose 0.0266 mcg per mouse as well as PMB did not influence the course of S. typhimurium infection in mice.

CONCLUSION

It was shown that rcHSP-LPS effectively protects mice from S. typhimurium infection by activating innate immunity; one of the possible mechanisms for such protection determined by interaction with TLRs 2 and 4 was considered. Other studies are needed in order to elucidate other mechanisms of innate immunity, which can be activated by rcHSP-LPS.

[Recombinant heat-shock protein (rHSP70) boosts activation of innate and adaptive immunity during simultaneous administration with bacterial antigens in experiment]

Experimental study of adjuvant effect of recombinant mycobacterial heat-shock protein rHSP70 on immune response to antigens of opportunistic microorganisms was performed. Therapeutic poly-component vaccine Immunovac-VP-4, containing ligands for binding with Toll-like receptors (TLRs) 2, 4 and 9, was used as a source of bacterial antigens. Obtained data showed that administration of rHSP70 mixed with bacterial antigens of opportunistic microorganisms leads to maturation of mice dendritic cells obtained from bone marrow precursors, increased expression of TLRs 2, 4, 9 on their surface and production of cytokines IL-1beta, IL-6, IL-10, TNFalpha, as well as to activation of innate immunity in experiments in vivo resulting to increased resistance of mice to experimental Salmonella infection. Simultaneous administration of rHSP70 with bacterial antigens increased titers of antibodies to vaccine's antigenic components in direct hemagglutination reaction. Thus, adjuvant effect of rHSP70 was confirmed on the used model as well as increase of stimulation of innate and adaptive immunity was shown.

[Functions of heat shock proteins in the system of adaptive immunity. Construction of vaccines]

One of the most important aspects of heat shock proteins (HSP) functioning, namely their role in reactions of innate and adaptive immunity, was reviewed in the article. Mechanisms of involvement of HSP in processing and presentation of antigens to T-lymphocytes were described. Principles of construction of prophylactic and therapeutic vaccines on the basis of HSP were set out. Assessment of range of indications for their use and possible risks related with inductive action of vaccines on the development of immunopathologic processes was a specially discussed topic.

[Complex of recombinant heat shock protein with lipopolysaccharide induces rapid protection of mice against Salmonella typhimurium and avirulent for humans avian influenza virus H5N2]

Protective effect of immunization with heat shock protein (HSP) against bacterial and viral infections in mice was studied. Recombinant HSP 70 kDa of Mycobacterium tuberculosis contaminated with lypopolysaccharide (0.185 mcg/ml) was used for experiments. One intraperitoneal injection of 100 or 400 mcg of HSP induced rapid protection against intraperitoneal challen e with 125 LD50 of Salmonella typhimurium (on 3rd-6th day) and against intranasal challenge with 10 LD50 of avirulent for humans avian influenza virus H5N2 (A/ mallard/Pennsylvania/10218/84) (on 5th-8th day). Three daily injections with 10 mcg of HSP induced rapid, significant and long-term protection against S. typhimurium. Immunization with HSP protected 100% of mice during 3 days after the challenge, 50% of immunized animals survived during 21 days (duration of the study). All nonimmunized mice died on 6th day.

[Role of heat shock proteins in developing of innate immunity reactions]

Increasing interest to heat shock proteins (HSP) from biologists and medics is connected to widespread distribution of HSP in live nature and reflects their key role in support of life functions which is based on the unique polyfunctionality of these biomolecules. Together with main function, which is defense of biologic systems from stress effects, some HSP in the process of evolution acquired the ability to incorporate in the reactions of the immune system. The in vestmen of this protein in practical reactions of innate immunity system are described. Analysis of mechanisms underlying the adjuvant effect of pro- and eukaryotic HSP in innate immunity system is presented. HSP receptor structures on target cells as well as triggered intracellular signaling pathways are described.

[Development and estimation of nanosomal rifampicin]

A lab-scale method for preparation of rifampicin-loaded polybutylcyanoacrylate nanoparticles (nanosames) was developed. The biodistribution of the nanosome-entrapped rifampicin after its intravenous administration was studied on healthy mice. The nanoparticles provided significant liver and spleen accumulation of rifampicin. Modification of the nanoparticles surface with poloxamer 407 or poloxamine 908 led to optimization of the biodistribution: the concentrations of rifampicin in the lungs and plasma increased, whereas the liver accumulation decreased vs. the unmodified nanoparticles. The increased lung accumulation of rifampicin enhanced bacterial clearance in the lungs of the mice infected with M. tuberculosis. The results showed that the use of the nanoparticles for optimization of the drug biodistribution was effective for increasing the efficacy of antiinfective chemotherapy.

Protein kinase A: regulation and receptor-mediated delivery of antisense oligonucleotides and cytotoxic drugs

Protein kinases help regulate eukaryotic cell division. We investigated the regulation of cAMP-dependent protein kinase A (PKA) and casein kinase (CK) type I activity in normal cells and in cancer. To assess this activity in biopsies we suggest a new parameter--the ratio of CK activity and total PKA activity divided by cAMP concentration: CK/PKA/cAMP. In 98 samples of colon mucosa in normal, inflamed, polyp, and adenocarcinoma cells, we found this parameter to be fairly constant in normal conditions and increased 10-fold in colon cancer; the ratio does not depend on the place of biopsy or the patient's age or sex. Experiments with model systems of concanavalin A-stimulated lymphocytes and regenerating rat liver showed that in normal cell proliferation the parameter increases 2-3-fold, as compared to a 30-fold increase in cancer. Unlike normal cells, malignant cells show CK activation and decrease of cAMP; therefore, PKA activity decreases. This suggests a correlation of CK and PKA activity and significant damage to their regulation at pathological changes of tissue proliferation. To further study concerted CK and PKA regulation we used monoclonal antibodies (mAbs) against cAMP-dependent protein kinase regulatory subunit RKII beta. We produced 11 antibodies in three groups: inhibiting, which block cAMP binding with RII beta and inhibit holoenzyme formation (RS6); activating, which enhance cAMP binding and do not affect holoenzyme formation (RS28); and neutral (RS17). To investigate mAb influence on protein kinase regulation in live cells we permeabilized pheochromocytoma PC12 by digitonin. When used at 5-microM concentration for 5 min, digitonin allowed us to deliver mAb into PC12 cells at 30-34-nM concentration, leaving 68-75% viable cells. Protein kinase activity was measured within 0.5 and 4 h after incorporation of mAbs into cells. After 30 min incorporation, mAb RS6 blocked PKA activation in PC12 cells under the influence of cAMP; other mAbs showed no effect. mAb RS6 caused a 4-fold increase of free C subunit activity 4 h after incorporation. mAb RS38 decreased R2C2 activity and did not influence C subunit activity. The change of free C subunit activity caused by mAb incorporation was followed by a synchronized, well-balanced change of CK type I activity, which suggests a correlation between the two phosphorylation systems of cell proteins.

Determination of cyclosporin A in 20% ethanol by a magnetic beads-based immunofluorescence assay

A rapid magnetic beads-based immunoassay for the immunodepressant drug cyclosporin A (CsA) has been developed. The method allows CsA determination in medium with a higher content of ethanol compared to conventional immunochemical techniques due to increased antibody stability. Monitoring of the drug in ethanol extracts from patient's whole blood without many-fold dilution with aqueous buffer is possible. The assay has adequate specificity and sensitivity for CsA to be suitable for the routine monitoring of therapy.

Incorporation of monoclonal antibodies in living rat pheochromocytoma PC12 cells. Evidence for the intracellular formation of immune complex between the incorporated antibody and a target protein

PC12 cells permeabilized with a low concentration of digitonin (5 microM) under controlled conditions were loaded with monoclonal antibodies (MoAb) against the regulatory subunit type II (RII) of cAMP-dependent protein kinase. After digitonin removal from the nutrient medium (DMEM) the loaded cells repaired within 20-30 min and recontinued growth. The inserted MoAb stayed in the repaired cells at least for several hours. MoAb inhibiting the cAMP binding activity of neural RII [Grozdova et al. (1992) Biochem. Int. 27, 811-822; Sveshnikova et al. (1996) Biochem. Int. 39, 1063-1070] were shown to bind the target antigen inside the cells and influence the properties of intracellular protein kinases.

Properties of the regulatory subunit of cAMP-dependent protein kinase type II from human brain

The regulatory subunit type II (RII) of cAMP-dependent protein kinase purified from human brain was represented by two proteins with apparent molecular masses of 51-52 kD and 54 kD. Dephosphorylation of human RII containing 3 mol phosphate/mol protein did not change the electrophoretic pattern. One-dimensional peptide mapping of 51-52 kD and 54 kD proteins after digestion with St. aureus V8 protease evidenced to their being distinct proteins. The data obtained permit to assume that human RII of neural type is represented by two isoforms.

Immunochemical studies on human, bovine and pig brain regulatory subunits of cAMP-dependent protein kinase type II

Regulatory subunits type II (RII) purified from human, pig and bovine brains were compared using II monoclonal antibodies (MoAb) against bovine brain RII. Bovine RII has at least 5 antigenic sites located in the N-terminal 1-110 residues. Immunochemical difference detected between human and animal RII was more pronounced than between pig and bovine RII. Certain MoAb influenced R-cAMP binding and holoenzyme formation. RII of the three species responded to MoAb attachment in a similar fashion. The results suggest that anchoring of neural protein kinase via the N-terminal part of RII may influence the enzyme activity.

Interaction of hydrophobized antiviral antibodies with influenza virus infected MDCK cells

The ability of artificially stearoylated antibodies to influenza virus hemagglutinin and M1 proteins to interfere with influenza infection in MDCK cells has been studied. Both the modified anti-hemagglutinin (polyclonal) and anti-M1 (monoclonal) antibodies neutralize the virus when added before the infection. The effect can be attributed to the interaction of stearoylated antibodies with the virus surface, which is enhanced by fatty acylation (anti-hemagglutinin), or to the antibody uptake in the cell endocytic compartments simultaneously with the virion which permits antibodies to interact with the virus envelope internal antigen (anti-M1). The stearoylated antibodies to hemagglutinin inhibit the virus reproduction being added to the infected cells. This effect is believed to be due to the interaction of the antibodies with newly synthesized hemagglutinin on the cell surface which disturbs the virus budding and assemblage; fatty acylation intensifying this interaction.

Identification of functionally active fragments of staphylococcal enterotoxin B

It has been found that staphylococcal enterotoxin B contains a proteolysis-sensitive sequence in the cysteine loop formed by two half-cystines located in the middle of the toxin polypeptide chain. Fragments of the enterotoxin formed as a result of its digestion in this region have been isolated, their N-terminal sequences have been determined and sites of proteolysis have been identified. It has been demonstrated that the N-terminal fragment of staphylococcal enterotoxin B is capable of activating T cell proliferation in the culture of human mononuclear cells practically to the same degree as the intact enterotoxin. The toxin's C-terminal fragment possesses an ability to activate calmodulin-dependent enzymes and is probably the toxicogenic part of the enterotoxin.

Antibodies to the regulatory subunit of cAMP-dependent protein kinase type II from bovine brain inhibit the holoenzyme formation

Mouse monoclonal antibodies to the bovine brain regulatory subunit type II (RII) were produced and antibodies of 11 clones were characterized. We determined their subclass, affinity constants, competivity and influence on two RII functions, namely cAMP binding and inhibition of the catalytic subunit (C) activity. 4 clones produced antibodies that increased RII-cAMP binding 1,5-2-fold. Antibodies of other 3 clones prevented R-C association and inhibition of C phosphotransferase activity. Some antibodies affected neither of these RII functions.

[The interaction of monoclonal antibodies to the structural proteins of the Vnukovo-32 vaccinal virus with other viruses of the rabies group]

The interaction of 7 monoclonal antibodies (MCA) to the nucleocapsid complex and 3 MCA to protein G of the vaccine virus Vnukovo-32 with 33 and 27 members of the rabies virus group, respectively, was studied. The indirect immunofluorescence test showed 7 MCA to the nucleocapsid complex to recognize 4 antigenic determinants (AD). Two MCA recognized the AD common for all the viruses under study. Individual ecological variants may be detected using other MCA. Three MCA to protein G had marked virus-neutralizing activity. MCA 1C5 neutralized all the rabies viruses under study. The other two MCA differed in the number of viruses they could neutralize. The viruses under study were divided into 4 groups depending on their interactions with certain MCA in neutralization test.

[A comparison of the results of analyzing the clinical data from gynecological, ophthalmological and dental patients using a set of rapid methods for the diagnosis of herpesvirus infection]

Analysis of biological specimens from gynecological, ophthalmological, and stomatological patients was carried out using current express methods for diagnosis of herpes virus infection developed by the authors: enzyme immunoassay (EIA), time-resolved fluoroimmunoassay (tr-FIA), molecular hybridization and conventional immunofluorescence technique. Monoclonal antibodies (MCA) generated by us with epitope specificity for gpD HSV-2 were used in EIA and tr-FIA. F(ab')2-fragments of MCA used as sorbents and for preparation of conjugates were found to be by 250% more sensitive than intact IgG used for similar purposes. The employment of EIA based on MCA F(ab')2-fragments contributed to detection of 0.2-0.6 ng of virus-specific protein in a specimen. Comparison of the results of analysis of clinical specimens of broad spectrum (mucous secreta from the cervical canal of the uterus and posterior vault of the vagina, saliva, lacrimal fluid) by the above express methods for diagnosis of herpes virus infection revealed a high percentage of positive findings, none of the methods providing 100% diagnosis. The use of a set of methods makes the resultant information more objective. Therefore, in future the data obtained by a number of current express methods for herpes diagnosis should be compared.

[Kinetics of immunoglobulin G transport through the multi-layer epithelial-hematic barrier of the respiratory tract]

A new class of drugs is now utilized for in vivo diagnoses and therapy of many widespread diseases. In these pharmacological and diagnostic preparations the active substance is conjugated with a vector which transports the drug to specific biological targets. Monoclonal antibodies are the most commonly used vectors: estimation of their permeability through multilayer and unilayer biomembranes is an important step in the analysis of efficiency of vector drugs. Experiments with Sprague-Dawley rats (mature females weighing 500 to 160 g) have demonstrated the ability of immunoglobulins G to penetrate through the respiratory epithelial-hematic barrier. Using solid phase ELISA, it was found that 5-25% of the total amount of mouse antiinsulin immunoglobulins G1 injected into the trachea under hexenal anesthesia can penetrate into the blood plasma. Accumulation of antibodies in the blood begins 4 hours and ceases 32 hours after the drug application in a dose of 400 micrograms. The kinetics of transmembrane transport is described by an S-like saturation function: C(t) = Cmax/(1+e-(at-b]. Penetration of monoclonal antibodies into the blood is accompanied by their distribution in the organs and tissues as well as by their clearance from the blood plasma. The clearance of monoclonal antibodies is characterized by a 24 hour half-life and is described by an exponential equation: C(t) = C0 x exp-kt. An algorithm for the interaction of these processes which should be taken into account during measurements of the transport of monoclonal antibodies and their complexes through biomembranes is proposed.(ABSTRACT TRUNCATED AT 250 WORDS)