Development of transplantable ascites tumours which continuously produce polyclonal antibodies in pristane primed BALB/c mice immunized with bacterial antigens and complete Freund's adjuvant

Remodelling of the nuclear lamina during human cytomegalovirus infection: role of the viral proteins pUL50 and pUL53

A fundamental step in the efficient production of human cytomegalovirus (HCMV) progeny is viral egress from the nucleus to the cytoplasm of infected cells. In the family Herpesviridae, this process involves alteration of nuclear lamina components by two highly conserved proteins, whose homologues in HCMV are named pUL50 and pUL53. This study showed that HCMV infection induced the mislocalization of nuclear lamins and that pUL50 and pUL53 play a role in this event. At late stages of infection, both lamin A/C and lamin B showed an irregular distribution on the nuclear rim, coincident with areas of pUL53 accumulation. No variations in the total amount of nuclear lamins could be detected, supporting the view that HCMV induces a qualitative, rather than a quantitative, alteration of these cellular components, as has been suggested previously for other herpesviruses. Interestingly, pUL53, in the absence of other viral products, localized diffusely in the nucleus, whilst the co-expression and interaction of pUL53 with its partner, pUL50, restored its nuclear rim localization in distinct patches, thus indicating that pUL50 is sufficient to induce the localization of pUL53 observed during virus infection. Importantly, analysis of the nuclear lamina in the presence of pUL50-pUL53 complexes at the nuclear boundary and in the absence of other viral products showed that the two viral proteins were sufficient to promote alterations of lamins, strongly resembling those observed during HCMV infection. These results suggest that pUL50 and pUL53 may play an important role in the exit of virions from the nucleus by inducing structural modifications of the nuclear lamina.

Characterization of a type I regulatory subunit of cAMP-dependent protein kinase from the bivalve mollusk Mytilus galloprovincialis

Two isoforms of the regulatory subunit (R) of cAMP-dependent protein kinase (PKA), named R(myt1) and R(myt2), had been purified in our laboratory from two different tissues of the sea mussel Mytilus galloprovincialis. In this paper, we report the sequences of several peptides obtained from tryptic digestion of R(myt1). As a whole, these sequences showed high homology with regions of type I R subunits from invertebrate and also from mammalian sources, but homology with those of fungal and type II R subunits was much lower, which indicates that R(myt1) can be considered as a type I R isoform. This conclusion is also supported by the following biochemical properties: (1) R(myt1) was proved to have interchain disulfide bonds stabilizing its dimeric structure; (2) it failed to be phosphorylated by the catalytic (C) subunit purified from mussel; (3) it has a higher pI value than that of the R(myt2) isoform; and (4) it showed cross-reactivity with mammalian anti-RIbeta antibody.

Analysis of intracellular and intraviral localization of the human cytomegalovirus UL53 protein

Human cytomegalovirus (HCMV) UL53 belongs to a family of conserved herpesvirus genes. In this work, the expression and localization of the UL53 gene product was analysed. Results obtained showed that pUL53 is a new structural protein. In infected human fibroblasts, pUL53 localizes in cytoplasmic perinuclear granular formations together with other structural viral proteins. In the nucleus, pUL53 forms patches at the nuclear periphery and co-localizes with lamin B at the internal nuclear membrane level. Immunoelectron microscopy studies have disclosed that nuclear pseudo-inclusions are labelled, whereas nucleocapsid formations within the intranuclear skein are negative. Furthermore, the mature virus particle maintains pUL53 at its tegumental level. These data suggest that pUL53 could be involved either in nucleocapsid maturation or in the egress of nucleocapsids from the nucleus to the cytoplasm through the nuclear membrane, a role compatible with the function hypothesized for UL31, its positional homologue in herpes simplex virus type 1.

Purification of a lipid-activated and Ca2+-independent protein kinase from the mantle tissue of Mytilus galloprovincialis Lmk

A phospholipid-sensitive Ca2+-independent protein kinase (p105) was purified to homogeneity from mantle tissue of the mussel Mytilus galloprovincialis Lmk., employing consecutively DE-52 cellulose, Sephacryl S-200 and Biogel HTP chromatographies. The purified enzyme appeared as a single band on 10% SDS-PAGE, and had a molecular weight of 105 kDa. The positive Western blotting of the purified eluate for anti-human-PKCdelta and PKCepsilon suggests that the enzyme from mussel mantle may be an ancestral nPKC isoform, with the kinetic properties of the enzyme very close to those of PKCepsilon isoform of vertebrates. Western blotting of samples from different steps of purification using specific mouse anti-p105, showed two protein bands in samples from the initial steps. However, only one band was detected in the Biogel-HTP eluate, the most purified fraction. The purification steps did not affect the presence of P-serine in p105. No P-tyrosine peptides were detected in any of the purification steps. These results open a new field of work on the study of several molecular processes related to energetic metabolism and reproduction in molluscs, whose regulation is associated with the activation of protein kinases.

Molecular characterization of cDNAs encoding G protein alpha and beta subunits and study of their temporal and spatial expression patterns in Nicotiana plumbaginifolia Viv

We have isolated cDNA sequences encoding alpha and beta subunits of potential G proteins from a cDNA library prepared from somatic embryos of Nicotiana plumbaginifolia Viv. at early developmental stages. The predicted NPGPA1 and NPGPB1 gene products are 75-98% identical to the known respective plant alpha and beta subunits. Southern hybridizations indicate that NPGPA1 is probably a single-copy gene, whereas at least two copies of NPGPB1 exist in the N. plumbaginifolia genome. Northern analyses reveal that both NPGPA1 and NPGPB1 mRNA are expressed in all embryogenic stages and plant tissues examined and their expression is obviously regulated by the plant hormone auxin. Immunohistological localization of NPGPalpha1 and NPGPbeta1 preferentially on plasma and endoplasmic reticulum membranes and their immunochemical detection exclusively in microsomal cell fractions implicate membrane association of both proteins. The temporal and spatial expression patterns of NPGPA1 and NPGPB1 show conformity as well as differences. This could account for not only cooperative, but also individual activities of both subunits during embryogenesis and plant development.

An investigation of the degradation of the plant toxin, ricin, by sodium hypochlorite

The toxin, ricin (0.4 microg/microl), was exposed to a range of sodium hypochlorite concentrations. SDS PAGE showed that hypochlorite caused the ricin to smear and decrease in mobility and, ultimately, caused a loss of silver staining. Cytotoxicity assays using dye uptake by Hep2 cells showed that treatment with 3 mM hypochlorite inactivated the ricin. Western blotting and ELISAs showed that binding by polyclonal antibodies raised against native ricin, or partially degraded ricin, diminished as hypochlorite degradation of the ricin increased.

Expression and characterization of a novel structural protein of human cytomegalovirus, pUL25

Human cytomegalovirus (HCMV) UL25 has recently been found to encode a new structural protein that is present in both virion and defective viral particles (C. J. Baldick and T. Shenk, J. Virol. 70:6097-6105, 1996). In the present work a polyclonal antibody was raised against a prokaryotic pUL25 fusion protein in order to investigate the biosynthesis and localization of the UL25 product (pUL25) during HCMV replication in human fibroblasts. Furthermore, pUL25 was transiently expressed in its native form and fused to the FLAG epitope, in COS7 and U373MG cells, in order to compare the properties of the isolated protein and that produced during infection. Immunoblotting analysis revealed a group of polypeptides, ranging from 80 to 100 kDa, in both transfected and infected cells; in vivo labeling experiments with infected cells demonstrated they are posttranslationally modified by phosphorylation. The transcriptional analysis of the UL25 open reading frame combined with the study of pUL25 biosynthesis showed true late kinetics for this protein in infected human fibroblasts. By indirect immunofluorescence both recombinant and viral pUL25 were detected exclusively in the cytoplasm of transfected or infected cells. Interestingly, pUL25 was shown to localize in typical condensed structures in the perinuclear region as already observed for other HCMV tegument proteins. Colocalization of ppUL99 in the same vacuoles suggests that these structure are endosomal cisternae, which are proposed to be a preferential site of viral particle envelopment. Our data suggest that pUL25 is most likely a novel tegument protein and possibly plays a key role in the process of envelopment.

Specific antibodies reactive with the 22-kilodalton major outer surface protein of Borrelia anserina Ni-NL protect chicks from infection

An outer surface lipoprotein of 22 kDa was identified in the avian pathogen Borrelia anserina Ni-NL by using antibody preparations reactive with bacterial surface-exposed proteins. Amino acid sequence analysis of the 22-kDa protein demonstrated 90% identity with VmpA of B. turicatae, suggesting that the protein belongs to the family of 20-kDa outer surface proteins of the genus Borrelia. All of the 60 chicks intramuscularly treated with antibodies specifically reacting with the 22-kDa protein and infected with strain Ni-NL were completely protected from infection, since no spirochetemia was detected, and from death. Control chicks were treated with immune sera raised against apathogenic strain B. anserina Es, which expresses a prominent 20-kDa polypeptide that is also a member of the Vmp family but does not cross-react immunologically with the 22-kDa protein of the Ni-NL strain. These animals, infected with B. anserina Ni-NL, showed a high degree of spirochetemia 10 days after infection, and all died between 14 and 21 days after infection. The results showed that the 22-kDa surface protein of B. anserina Ni-NL is a determinant of the pathogenic potential of the strain and also confirmed that only strain-specific antibodies are protective against B. anserina infection.

Detection of serum antibodies to CagA and VacA and of serum neutralizing activity for vacuolating cytotoxin in patients with Helicobacter pylori-induced gastritis

Thirty patients with dyspepsia, with histological diagnosis of gastritis, and with endoscopic diagnosis of peptic ulcer disease (PUD) (n = 13) or nonulcer dyspepsia (NUD) (n = 17) were admitted to the study. Helicobacter pylori vacuolating cytotoxin-producing strains (Tox+) were isolated from 14 (46.7%) patients, whereas non-cytotoxin-producing (Tox-) H. pylori strains were isolated from the remaining patients. Of 30 patients studied, 20 (66.7%) had serum cytotoxin neutralizing activity in vitro. Fourteen patients with Tox+ H. pylori strains showed serum cytotoxin neutralizing activity and serum immunoglobulin G (IgG) and IgA antibodies reactive with both 87-kDa H. pylori vacuolating cytotoxin (VacA) and 128-kDa cytotoxin-associated gene product (CagA) by immunoblotting using native enriched preparations of VacA and CagA proteins from H. pylori culture supernatants as the antigens. A 94-kDa antigen cross-reacting with the 87-kDa VacA protein could be demonstrated in culture supernatant with immune sera from humans and animals. All patients (n = 10) lacking serum neutralizing activity were also negative for IgG or IgA against VacA antigen, whereas 6 of the 10 patients showed IgG serum antibody responses against CagA antigen. The prevalence of antibodies to VacA and CagA antigens was significantly (P < 0.001) higher in patients with gastritis (20 and 26 patients for VacA and CagA, respectively, of 30 patients) than in H. pylori culture-negative controls (0 of 27 for both VacA and CagA) and in randomly selected blood donors (17 and 21 for VacA and CagA, respectively, of 120 subjects). All patients with PUD had antibodies to CagA, whereas 13 of 17 (76.5%) patients with NUD had anti-CagA antibodies. Serum IgG antibodies to VacA were present in 9 (69.2%) patients with PUD of 13 patients and in 11 (64.7%) patients with NUD of 17 patients. Anti-CagA antibodies seemed to correlate better with PUD than anti-VacA antibodies.

Characterization of immunorelated peptides to porcidin P1

Porcidin P1, an antimicrobial peptide purified from the granules of porcine polymorphonuclear neutrophils (PMN) using ultrafiltration and reverse phase high performance liquid chromatography (RP-HPLC), was covalently conjugated to BSA and used to generate monospecific polyclonal ascites. Antibodies raised against porcidin P1 were covalently coupled to an Affi-gel Hz affinity column and used for immunoaffinity chromatography of peptides from porcine PMN cell extract. Eleven immunorelated peptides were eluted from the column from neutrophil cell extracts and purified to homogeneity by HPLC. The molecular weights of the immunorelated peptides were determined by mass spectral analysis and ranged in size from 1.91 to 10.65 kDa. Of the 11 immunorelated peptides which were bound to the affinity column, only six peptides were recognized by the anti-porcidin antibodies after HPLC purification. Three immunoreactive peptides displayed potent antibacterial activity towards Staphylococcus aureus and Escherichia coli, reducing viability by as much as 99.9% (> 3 log reduction in CFU) when 5 mu g/mL of each purified peptide was used. The polyclonal monospecific antibodies also reacted with proteins from ovine and human PMN, illustrating possible structural relationships between small antibacterial peptides from the different species.

Functional activities of antibodies directed against surface lipoproteins of Borrelia hermsii

Enriched preparations for mouse polyclonal immunoglobulin G (IgG) antibodies reactive with surface-exposed epitopes (Ab-SEE) of the 22-kDa and 24-kDa membrane lipoproteins of living Borrelia hermsii (HS 1 strain) cells were obtained by an antibody absorption technique using living spirochetes. In vitro, the antibody preparations both inhibited spirochetal growth and were borreliacidal in the presence of complement. The monovalent Fab antibody fragments, prepared from antibody-enriched preparations, did not inhibit the growth of the bacteria, whereas they killed the bacteria in the presence of complement. The two-dimension gel electrophoresis of B. hermsii cells showed that 3H-labeled fatty acids incorporated into the 22-kDa and 24-kDa lipoproteins were resolved into one and three compact spots, respectively. The spots were recognized by the Ab-SEE preparations reactive with the 22-kDa and 24-kDa proteins, by Western blotting.

Animal and human antibodies reactive with the outer surface protein A and B of Borrelia burgdorferi are borreliacidal, in vitro, in the presence of complement

Polyspecific antibodies present in ascitic fluids of mice (pMIAFs) immunized with whole Borrelia burgdorferi cells exerted borreliacidal activity in vitro when tested with complement and homologous antigen but not with heterologous B. hermsii. Similarly, monospecific mouse antibodies obtained by immunizing mice with purified preparations of outer surface protein A and B of B. burgdorferi were borreliacidal. On the contrary, mouse monospecific antibodies raised against the 41-kDa flagellar protein of B. burgdorferi did not kill borreliae in the presence of complement. A complement-mediated, in vitro, borreliacidal activity was observed in human sera from patients with Lyme disease when antibodies against OspA and/or OspB were detectable in sera by the Western blotting technique. The in vitro borreliacidal activity of human sera was evident after 14 h incubation with live B. burgdorferi spirochaetes and complement, whereas antibodies present in mouse immune ascitic fluids killed borreliae after 1 h incubation.

Mice ascites as a source of polyclonal and monoclonal antibodies

A large quantity of polyclonal anti-ovalbumin antibodies was obtained from mice by a simple modification of the method described by Kurpisz et al. (1988). In addition, the cells from ascitic fluid were used to produce monoclonal antibodies. Egg ovalbumin hyperimmunized BALB/c mice were injected successively with pristane, antigen and a non-antibody secreting myeloma cell line: the production of ascitic fluid containing antiovalbumin antibody activity was observed after 10-25 days. Cells from ascitic fluid were harvested, washed and fused together with polyethylene glycol to produce monoclonal antibodies. Two fusions were performed and a large number of monoclonal anti-ovalbumin antibodies was obtained. This method is simple, reproducible, allows many fusions to be obtained from one mouse, and allows the use of ascitic B cells rather than the more, frequently used splenic B cells.

Surface immunofluorescence assay for diagnosis of Lyme disease

A surface immunofluorescence assay (SIFA) was analyzed and compared with a conventional indirect immunofluorescence assay (IFA) and whole-cell enzyme-linked immunosorbent assay (ELISA) for detecting immunoglobulin G (IgG) antibodies to Borrelia burgdorferi in sera from patients with Lyme disease. Fifty-five patients with syphilis and 33 patients with rheumatoid arthritis were used as disease controls. The sensitivity of the SIFA was low during the acute phase of Lyme disease (sera from seven of nine patients presenting with erythema chronicum migrans were negative during the first 2 months of illness); later, seroconversion was observed in all patients at various times during convalescence. Sera from five patients with complicated Lyme disease were strongly positive. SIFA was found to be highly specific, since sera from all patients with secondary or latent syphilis and patients with rheumatoid arthritis did not react in the test. Strong cross-reactivity occurred when these sera were tested in conventional IFA and ELISA; sera from 38 (69%) patients with syphilis were positive by IFA and sera from 51 (93%) patients were positive by ELISA, whereas 7 (21%) and 12 (36%) of the serum samples from patients with rheumatoid arthritis were positive by IFA and ELISA, respectively. Immunoblot analysis of SIFA-positive sera showed that the 31- and 34-kDa outer surface proteins (proteins A and B, respectively) of B. burgdorferi were the major reactive antigens involved in the test. The results support a role for SIFA in the investigation of complicated Lyme disease as well as in the differentiation of Lyme disease from other diseases associated with B. burgdorferi cross-reactive antibodies.

Detection of glycoproteins in Borrelia burgdorferi

The presence of carbohydrates on proteins of Borrelia burgdorferi, the causative agent of Lyme disease, was investigated by using a digoxigenin labeling method together with Schiff staining and N-glycosidase F assay. The two major outer surface exposed proteins of 31 kDa and 34 kDa showed to be glycosylated and gel filtration high pressure liquid chromatography (HPLC) of proteins of B. burgdorferi metabolically labeled with 14C-N-acetylglucosamine revealed the incorporation of the carbohydrate into the glycosyl residue of these proteins.

Immunological characterization of a low molecular mass polypeptidic antigen of Borrelia burgdorferi

The presence of a low molecular mass polypeptidic antigen in Borrelia burgdorferi was described. The protein was exposed at the bacterial surface since it was clearly identified by mAb 3H4 using the immunofluorescence test performed with living bacteria. This antigen was cleaved by proteinase K treatment, whereas it was resistant to the action of chymotrypsin, trypsin and thermolysin. Western blotting analysis of the immunological reactivity of this antigenic structure performed using monoclonal antibody, mouse-immune ascitic fluids raised against B. burgdorferi and other spirochetes, sera from patients with Lyme disease and other infirmities in which false positive results in serological tests for B. burgdorferi have been described, demonstrated that this protein expresses only species-specific epitopes which may be recognized during human B. burgdorferi infections.