Showing papers in "Acta Virologica in 1996"

Detection of hepatitis B virus DNA in hepatitis B surface antigen-negative serum by polymerase chain reaction: evaluation of different primer pairs and conditions.

Abstract: The presence of hepatitis B virus (HBV) DNA was investigated by polymerase chain reaction (PCR) in the serum of twenty Brazilian blood donors. All sera were negative for hepatitis B surface antigen (HBsAg), 17 of them presented antibodies to the hepatitis B core antigen (anti-HBc) as the unique serological marker of HBV infection, and 3 were positive for antibodies to HBsAg (anti-HBs) and anti-HBc. PCR assays were carried out using different pairs of oligonucleotides designed from conserved sequences of C, pre-S and S regions of the HBV genome. First, all oligonucleotide pairs were tested in PCR using plasmids carrying HBV genome from ayw or adw strains as templates. One-round PCR assays were able to detect 100-25,000 molecules of plasmid DNA, depending on the oligonucleotide pair, while semi-nested PCR assays detected 10-1000 molecules. The frequency of HBV DNA-positive results with HBsAg-sera varied from 0% to 50% depending upon the PCR assay. The results indicated that a number of both isolated anti-HBc and anti-HBs+, anti-HBc+ samples contained HBV DNA at a very low concentration, neighboring the limit of detection.

Susceptibility of laboratory-bred rodents to the experimental infection with dengue virus type 2.

Abstract: Various strains of laboratory-bred rodents viz. mice [Swiss, C57BL/6, C3H/Hej, DBA/2, BALB/c, NMRI (nu/nu) and BL6 (nu/nu) and their heterozygous siblings (nu/+)], Mastomys natalensis, Wistar rat, golden hamster and Indian desert gerbil were inoculated intracerebrally (ic) with mouse-adapted dengue virus type 2 (DV-2). The inoculated animals were observed daily for dullness, anorexia, occult blood in faeces, patechial haemorrhages, lacrymation, paralysis, cachexia, death. Necropsied animals were examined for gastrointestinal haemorrhages and lymphadenopathy. The severity of clinical symptoms in various rodents declined as follows: (i) BL6 (nu/nu) mice exhibited most severe manifestation of all the aforementioned symptoms followed by (ii) NMRI (nu/nu), (iii) BL6 (nu/+) (iv) NMRI (nu/+) and C57BL6, (v) DBA, C3H/Hej and BALB/c, and (vi) Swiss. These results indicate that adaptation of DV-2 to the mouse may be an important factor in exaltation of virulence. Interstrain variation in manifestation of symptoms in mice indicates that the susceptibility to DV-2 may be determined by host genetic factors.

Envelope gene sequence variation among Japanese encephalitis viruses isolated in Korea.

Abstract: The nucleotide (nt) sequences of the envelope (E) gene of 4 Japanese encephalitis virus (JEV) isolates from Korea (K82PO1, K87P39, K91P55 and K94PO5) were determined and the deduced amino acid (aa) sequences were compared within themselves and with the published sequences of 16 other JEV strains originating from other parts of Asia. Homologies of 87.2 - 95.6% at the nt level and 95.8 - 98.0% at the aa level among the Korean JEV isolates were found. aa positions 89, 129, 220, 225, 327, 366, 456 and 477 characterized the Korean isolates. According to the phylogenetic analysis based on the E gene nt sequence, the Korean isolates formed distinct subgroup consisting of at least 2 genetic types.

Phylogenetic analysis of pestivirus based on the 5'-untranslated region.

Abstract: A phylogenetic tree of pestiviruses constructed by analyzing their 5'-untranslated region (UTR) indicated that the genetic relatedness between border disease virus and hog cholera virus is much closer than that between genotypes of various bovine diarrhoea viruses. This suggests that these viruses are host variants within a single species, which can be distinguished by comparison of secondary structures at three variable loci in the 5'-UTR.

Detection of sugarcane bacilliform virus in sugarcane germplasm.

Abstract: Sugarcane bacilliform virus (SCBV), a badnavirus was found in sugarcane genotypes of Saccharum officinarum L., S. barberi Jesw., S. sinense Roxb., S. robustum Brand and Jesw., and Saccharum hybrids. In most of the suspected genotypes the virus was found associated with clear foliar symptoms. However, certain symptom-free clones carried the virus too. The virus was detected by immuno-electron microscopy (IEM) and enzyme-linked immunosorbent assay (ELISA) in suspected clones. The virions measured about 108-118 x 20-21 nm in size. The virus was serologically closely related to another badnavirus, banana streak virus (BSV). Virus titer was low in most of the genotypes. However, a close correlation between symptoms expression and virus titer existed in some genotypes.

Protein-tyrosine phosphatase activity of Coxiella burnetii that inhibits human neutrophils.

Abstract: Supernatants prepared from disrupted Coxiella burnetii possess acid phosphatase (ACP) activity that apparently accounts for the inhibition of the metabolic burst of formyl-Met-Leu-Phe(fMLP)-stimulated human neutrophils. Results are presented regarding purification and biochemical-biological characterization of the ACP. The highly purified enzyme, which exhibited an apparent M(r) of 91 K and optimal activity at pH 5.0, also inhibited neutrophils. The enzyme retained full activity at pH 4.5, 5.5, and 7.4, when incubated overnight at 0 degrees C and room temperature; at pH 5.5, it retained full activity after overnight incubation at 37 degrees C. Apparently, the enzyme contains asparagine-linked but not serine- or threonine-linked glycan residues since its treatment with N-glycosidase F (PNGase F) decreased its M(r) to 87 K and no changes were detected with O-glycosidase. The enzyme's capacity to hydrolyze phosphate from a number of phosphate-containing compounds was examined; five phosphocompounds were significantly hydrolyzed: 5'-CMP > fructose 1,6-diphosphate > tyrosine phosphate > 3'-AMP > 5'-AMP. The ACP also dephosphorylated (32)P-Raytide, a phosphotyrosine-containing peptide. Dephosphorylation of Raytide was inhibited by the following phosphatase inhibitors: sodium molybdate, potassium fluoride, sodium ortho-vanadate and D2, a heteropolymolybdate compound. These results indicate that C. burnetii ACP may play a role in disrupting tyrosine phosphorylation/dephosphorylation reactions associated with the signal transduction pathway culminating in the metabolic burst. Interestingly, Western blot analysis of ACP-inhibited neutrophils showed a marked increase in tyrosine phosphorylation of a 44 K protein as compared to uninhibited cells.

Maturation of respiratory syncytial virus within HEp-2 cell cytoplasm.

Abstract: Electron microscopy of HEp-2 cells infected with respiratory syncytial virus (RSV) strain Long revealed the maturation of RSV on an ultrastructural level. The results showed that the virus maturated by two different pathways. In one of them, the virus assembled and matured before reaching the plasma membrane on the internal vesicle membrane within cytoplasm. The mature virus was delivered to the plasma membrane and to the extracellular space most likely by the transport vesicles and exocytosis. In the other pathway, the virus matured on the plasma membrane as described with other members of the family Paramyxoviridae. Using monoclonal antibodies (MoAbs), we localized viral nucleoprotein (NP) and envelope proteins in cytoplasm by immunoelectron microscopy (IEM).

Type 2 poliovirus recombinants isolated from vaccine-associated cases and from healthy contacts in Brazil.

Abstract: In a previous study (Friedrich et al., 1995b) P2/Sabin-derived strains isloated in Brazil from vaccine-associated paralytic poliomyelitis (VAPP) cases and from healthy contacts were analyzed for the presence of mutations at nucleotide (nt) 481 in the 5'-noncoding region (5'NCR) and at the codon of amino acid (aa) 143 of the capsid protein VP1, that are known to increase neurovirulence. In the present study a part of the 3Dpol-coding region of these strains was sequenced (3Dpol seq.) with the aim to find recombinant strains. In the 3Dpol seq., four out of ten strains isolated from VAPP cases turned out to be recombinants: one had 3Dpol seq. from the P1/Sabin strain, while the second had a part of 3Dpol seq. both from the P2/Sabin and P1/Sabin strains; the third and fourth recombinants had 3Dpol seq. from non-vaccine strains. The strains isolated from healthy contacts of the two VAPP cases, from which type 2 vaccine/non-vaccine recombinant strains were isolated, also consisted from recombinant genomes with the same nt sequences as those of the isolates from VAPP cases, confirming the transmission of P2/Sabin-derived recombinants. Comparison of the aa sequence of the viral RNA polymerase of the P2/Sabin strain with the predicted aa sequences of these recombinants in 3Dopl seq. demonstrated that an aa 69 (Asp-->Glu)) substitution was observed in most of the recombinant genomes, while an aa 113 (Thr-->Ser) substitution was observed in all the recombinant genomes. The possibility that the genomic recombination increased the neurovirulence of these strains cannot be excluded.

Chronic infection of Balb/c mice with murine herpesvirus 72 is associated with neoplasm development.

Abstract: One hundred Balb/c mice were infected with murine herpesvirus strain 72 (MHV-72) and observed for 2.5 years for neoplasm development and virus presence in tumour as well as non-tumour tissues. Out of 13 neoplasm-bearing mice the virus was recovered from solid tumours (one lymphoma, two non-differentiated lymphoblastomas and two fibrosarcomas) of five mice and from the spleen of one mouse with lymphatic leukemia. The virus persisted frequently also in various organs of the neoplasm-bearing mice.

Diagnostic importance of heterophile antibodies and immunoglobulins IgA, IgE, IgM and low-avidity IgG against Epstein-Barr virus capsid antigen in children.

Abstract: The use of several serological markers in diagnostics of acute Epstein-Barr virus (EBV) infection in children and adolescents is recommended. We investigated the sera of 299 individuals with clinically suspect infectious mononucleosis for heterophile antibodies and EBV viral capsid antigen (VCA)-specific immunoglobulins IgA, IgE, IgM and low-avidity IgG. Heterophile antibodies were positive in 26%, VCA-specific IgA in 30%, IgE in 35%, IgM in 32% and low-avidity IgG in 37% of cases. The acute EBV infection defined as a case having either positive IgM or heterophile antibodies was present in 40% of persons. Compared with regard to this criterion the sensitivity, specificity, and positive and negative predictive values of individual tests were as follows: heterophile antibodies-66, 100, 100 and 82%; IgA-53, 84, 69 and 73%; IgE-54, 78, 62 and 72%; IgM-81, 100, 100 and 89% low-avidity IgG-66, 82, 71 and 78%. All markers except heterophile antibodies were positive even infants aged below 2 years. We consider the detection of low-avidity IgG and VCA-specific IgE an useful adjunct for the diagnostics of acute EBV infection in children.

Classification of turnip mosaic virus isolates according to the 3'-untranslated region.

Abstract: The 3'-untranslated region (3'UTR) of five isolates of turnip mosaic virus (TuMV) from United Kingdom, Canada, Greece, the Czech Republic and from Uzbekistan were sequenced and compared with another nine previously sequenced TuMV isolates All the isolates had 209 nucleotides long 3'UTR, with the exception of the Uzbekistan isolate, which had one-base deletion at nucleotide (nt) position 162 Phylogenetic analysis identified three clusters of related isolates The clusters correlated with secondary folding of the 3'UTRs, partially with the source host plant of the isolates but not with their geographical origin

Genomic modifications in Sabin vaccine strains isolated from vaccination-associated cases, healthy contacts and healthy vaccinees.

Abstract: The three attenuated strains developed by A.B. Sabin have been effectively used as an oral live poliovirus vaccine (OPV) to control poliomyelitis in many countries. Although rarely, vaccination-associated paralytic poliomyelitis (VAPP) cases occur with the type 2 and 3 strains, and less frequently with the type 1 strain. The greater number of attenuating mutations in the P1/Sabin strain is probably reflected in the higher safety of this strain in comparison to type 2 and 3 strains. For the P1/Sabin strain, many attenuating mutations were already identified in the 5'-non-coding region (5'NCR), in the capsid proteins coding region, in the 3Dpol coding region, and the 3'-non-coding region (3'NCR). For the P2/Sabin and P3/Sabin strains, one mutation in 5'NCR and another in the capsid proteins coding region have been demonstrated to be important determinations of attenuation, although it has been suggested that other mutations may also have some effect, though minor. Although reverting mutations in attenuating determinants, suppressor mutations, mutations in antigenic sites and genomic recombination have been observed in strains isolated from VAPP cases, the observation of similar genomic modifications in strains isolated from healthy contacts and from healthy vaccinees has supported the view that host factors are also involved in the establishment of the disease. Reverting mutations at nucleotides (nt) 480 (G-->A), 481 (A-->G) and 472 (U-->C) for the P1/Sabin, P2/Sabin and P3/Sabin strains, respectively, have been detected in almost all strains isolated from VAPP cases and also from healthy vaccinees. Although the Sabin vaccine strains have been implicated in rare VAPP cases, recent studies have suggested that the vaccine strains could also trigger the Guillain-Barre syndrome (GBS), transverse myelitis (TM) and facial paralysis.

Genotypic identification of three new strains of spotted fever group rickettsiae isolated in China.

Abstract: Polymerase chain reaction (PCR) and restriction endonuclease fragment length polymorphism (RFLP) analysis were used to characterize the genotypic diversity of three isolates of spotted fever group (SFG) rickettsiae isolated from ticks in China. A primer pair designed from DNA sequence encoding 190 K protein antigen of R. rickettsii and genomic DNAs obtained from the isolates were used in PCR. The PCR products were cleaved with restriction endonucleases PstI and RsaI, and the digestion patterns were analyzed by polyacrylamide gel electrophoresis (PAGE) and compared with those of all known species and strains of SFG rickettsiae. The results showed that three isolates had the same PCR products as the other SFG rickettsiae under comparison. HL-93 strain, isolated from Hemophysalis concinna ticks collected in Hulin County, Heilongjiang Province, had unique PstI digestion pattern among SFG rickettsiae; strains BJ-93 and 053, isolated from Dermacentor sinicus and Haemaphysalis concinna ticks collected in Changping County, Beijing City, and Suifenhe City, Heilongjiang Province, respectively, had the same PstI and RsaI digestion patterns as strains R. sibirica 246, BJ-90 and IMTO-85. The present study demonstrated that the BJ-93 and 053 strains were genotypically identical with R. sibirica and the HL-93 strain was genotypically unique among SFG rickettsiae.

Cytotoxic T lymphocyte control during ectromelia (mousepox) virus infection: interaction between MHC-restricted cells analyzed by non-radioactive fluorometry.

Abstract: Cytotoxic T lymphocyte (CTL) activity of draining lymph node (DLN) cells isolated from BALB/c mice infected with ectromelia virus (EV) was examined using a fluorometric cell-mediated cytotoxicity (CMC) assay. Specific lysis of target cells A20 and EMT-6 primed with EV was demonstrated. The classical CD8+ cytolytic pathway dominated (72.7%) as compared to that of CD4+ (27.3%) in the cellular response during acute EV infection. Also an alternative method for determining CMC, employing a bisbenzamide dye for labelling target cells, is described. Coefficient variations of relative fluorescence were below 6%, that makes the method sensitive and reliable.

Inhibition of hepatitis B virus in vitro by antisense oligonucleotides.

Abstract: A series of antisense phosphorothioate oligodeoxynucleotides against hepatitis B virus (HBV) were synthesized and evaluated for their antiviral effect in Hep-G2 cells transfected with HBV genome. The inhibitory effect of the tested antisense oligonucleotides was sequence-specific, dose-and time-dependent, and synergistic for certain combinations. In virus-inhibitory concentrations the oligonucleotides were harmless to 2.2.15 cells. The most effective antisense oligonucleotides were found directed against the HBV mRNA transcribed from the cap site of SP II promoter, the portion of polyadenylation signal and the initiation region of gene S, with an inhibition of the HBsAg and HBeAg production by 85-95% and 50- 60%, respectively. To our surprise, antisense oligonucleotides directed against three key sites of HBV X gene blocked the expression of HBsAg, HBeAg and HBxAg. This fact might be related to the trans-activation of HBV X protein. Using radioisotope labelling, we demonstrated that Lipofectin promoted the cellular uptake and antiviral effect of antisense oligomers in 2.2.15 cells. These results suggest a therapeutic potential of antisense oligonucleotides in the treatment of patients chronically infected with HBV.

Experimental infection with a persistent influenza C virus variant leads to prolonged genome detection in the chicken lung.

Abstract: A persistent variant of influenza C virus was used to infect chickens by intraamniotic (i.a.) inoculation. The infected hatchings were analyzed for virus production in different tissues and for the continuous presence of viral RNA genomes. The permissiveness for infection was demonstrated primarily for the chicken lung, besides other organs. Viral antigens could be detected by indirect immunofluorescence staining for a period of 8 days and reisolates were obtained mainly at early time points post infection (p.i.). Nested reverse transcription-polymerase chain reaction (RT-PCR) directed to 3 genomic sequences was positive at least until day 53, whereby no distinct end point was determined. These experiments provide first evidence for the long-term stability of influenza C virus RNA segments in vivo.

First findings of plum pox virus in walnut trees (Juglans regia L.).

Abstract: Plum pox virus (PPV) was transmitted from infected buds and leaves of walnut tree (Juglans regia L.) on the following herbaceous indicators: Chenopodium foetidum Schrad., Nicotiana bigelovii var. quadrivalvis Fuchs., N. clevelandii x N. glutinosa. A positive ELISA reaction with antisera against PPV was obtained from infected buds and leaves of Juglans regia L. and from attacked leaves of indicator plants.

Evaluation of latex agglutination test for rapid detection of goat poxvirus antigen and antibodies

Abstract: Soluble antigen fraction of goat poxvirus (GPV) separated from infectious viral particles by ultracentrifugation of skin scab suspensions prepared from experimentally infected goats was employed for the first time to diagnose goat pox. The antiserum raised against this fraction was found to be specific and not reactive with healthy goat skin extracts. Subsequently, a latex agglutination (LA) test has been developed and standardized for the rapid detection of GPV antigen or antibody in skin scab suspensions or serum samples, respectively. In comparison to the counter immunoelectrophoresis (CIE) test the LA test was more sensitive in the detection of GPV antibodies, but equally sensitive in the detection of GPV antigen. The LA test can be taken for a simple and quick diagnostic tool for primary screening of goat pox.

Effect of immunosuppression on Balb/c mice infected with murine herpesvirus.

Abstract: Balb/c mice were infected with murine herpesvirus (MHV-72) and subjected to immunosuppression (IS) with the antibiotic FK506 either during the acute or chronic phase of infection. Attempts to detect virus in various organs of immunosuppressed and non-immunosuppressed mice at different time interval were made. In the mice immunosuppressed on days 3-23 p.i. of the acute phase of infection virus was detected in various tested organs and tissues at 2.0 times higher rate than those of control mice. At later intervals of the acute phase of infection (56-84 days p.i.) virus was still recovered in bone marrow and lymph nodes peritoneal cells of immunosuppressed mice, but not in those of control animals. In the chronically infected mice immunosuppressed on days 290-320 p.i., the virus was detected in lungs, thymus, bone marrow, spleen and peritoneal cells at 3.5 times higher rate than in those of control mice.

Identification and characterization of differentiating soluble antigens of sheep and goat poxviruses.

Abstract: Soluble antigens of sheep and goat poxviruses (SPV, GPV) were isolated and purified from scab suspensions prepared from lesions of experimentally infected homologous hosts. The soluble antigens were then subjected to sequential ammonium sulphate precipitation. All the obtained fractions reacted in counter immunoelectrophoresis (CIE) with both the antisera against SPV and GPV except the fraction obtained at 30% saturation level (30% SSPV), which did not react with antiserum against GPV. This differentiating soluble SPV antigen was found to consist of 210 K proteins in exclusion chromatography. The 210 K proteins contained 3 polypeptides of 100, 35 and 17 K in polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE). The study thus gave an evidence that the SPV-specific proteins are of a higher molecular mass nature.

Growth of hepatitis A virus in murine cells.

Abstract: In order to investigate the growth of hepatitis A virus (HAV) in murine cells, L929 cells of the established mouse cell line were transfected with the virion RNA or infected with the virions and examined for the formation of negative-strand RNA and the rise of the viral infectivity titer. In both the transfected and infected cells, the formation of negative-strand HAV RNA was assayed by the reverse transcription-polymerase chain reaction (RT-PCR). In the transfected cells, infectious HAV of an average titer of 10(1.8) TCID50/dish was obtained. The experiment with the virion infection was further extended by using other mouse cell lines, namely Balb/3T3 clone A31, NIH/3T3, and Swiss/3T3. Here, only NIH/3T3 cells were found capable to support the formation of negative-strand HAV RNA. Thus some murine cell lines are considered to have a complete cellular machinery for supporting the growth of HAV, though the efficiency of virus growth therein was considerably lower as compared to that in the susceptible primate cells.

Neutralization of human immunodeficiency virus type 1 (HIV-1) with antibody from carriers' plasma against HIV-1 protein p17.

Abstract: It was investigated whether human antibody against HIV-1 protein p17 (anti-p17) in HIV carriers' plasma has the ability to neutralize the infectivity of HIV. By the pretreatment of HIV-1 with anti-p17 from HIV carriers, progeny HIV-1 production from cells infected with virus pretreated with anti-p17 was suppressed and/or delayed. The neutralizing activity of anti-p17 was decreased in the presence of recombinant p17. The latter obviously masked the neutralizing activity of anti-p17. The relevant epitope(s) on p17 is located apparently on the surface of HIV virions and the binding of anti-p17 to p17 impairs the infectivity of HIV. This implies that anti-p17, if stably present in HIV carriers' plasma, may also play an important role in reducing the infectivity of HIV-1 in vivo.

Stability of foot-and-mouth disease virus, its genome and proteins at 37 degrees C.

Abstract: Infectivity titers of foot-and-mouth disease virus (FMDV) types Asia 1 and 0 were reduced by 4 and 2 log units, respectively, after incubation at 37 degrees C for 12 hrs. The stability of the FMDV RNA genome at 37 degrees C was studied using 32P-labelled virus. The RNA of FMDV type 0 was found to be more stable than that of type Asia 1. Oligo(dT)-cellulose chromatography showed that 21% and 31% of the labelled RNA were bound to the column in the case of types Asia 1 and 0, respectively. Possible correlation between the poly(A) tail length, accessibility of the genome to nucleases and thermostability of the infective virus is discussed. A positive correlation between the thermostability of the genome and general distribution of a particular virus type seems to exist. A stable genome associated with poor virus immunogenicity may be responsible for the prevalence of FMDV type 0 in the nature. The isoelectric focussing of structural proteins isolated from the virus samples incubated at 37 degrees C revealed charge differences in the major immunogen between the two FMDV types. A rapid proteolytic degradation of the viral immunogen and stability of the genome may be responsible for frequent outbreaks of FMD, at least, in the endemic countries.

Sequence analysis of VP7 gene of two Nigerian rotavirus strains.

Abstract: The complete nucleotide sequences of gene 9 (VP7) of rotavirus strains MGH66 and RHIB55 isolated in northern and southern Nigeria, respectively, were determined. The sequence of either strain was 1062 nucleotides along with two potential glycosylation sites and two in-phase initiation codons encoding a protein of 326 amino acids provided the first ATG codon was utilised. Comparison of the deduced amino acid sequences of VP7 of the strains with that of published sequences of serotype G1 strains and a representative strain of each of serotypes 2-6 and 8-14 revealed > or = 91.41% and > or = 81.60% homology, respectively. The stool sample obtained from a diarrhoeic child in Maiduguri containing strain MGH66 was classified by polymerase chain reaction (PCR) technique as possessing a dual infection specificity of VP7 serotypes G1 and G3. The nucleotide sequencing, however, revealed the dual infection specificity of VP7 serotypes G1 and G8. The implications of nucleotide sequence analysis for serotyping of rotavirus strains originating from different geographical regions and for vaccine development are discussed.

Autoimmune component in individuals during immune response to inactivated combined vaccine against Q fever.

Abstract: Serum samples from 20 individuals immunized with inactivated combined vaccine (ICV) against Q fever and 10 individuals that received placebo were investigated on days 14, 21, 28 and 60 after immunization by isotope specific enzyme-linked immunosorbent assay (ELISA) for the presence of antibodies directed to human IgA, IgM and IgG, and their fragments (F(ab')2, Fab, Fc). None of the subjects that received placebo exhibited significant increase of reactivity with any of the used antigens. By contrast, the sera of immunized individuals tended to show increased autoantibody activity with diverse antigens. Forty % of sera of immunized subjects exhibited anti-Fab activity, 20% of the sera recognized IgA, F(ab')2- and Fc-fragments, and 15% of the sera recognized IgG and IgM. Although there was wide variation in antibody levels and in isotypic heterogeneity of autoantibodies induced by immunization, anti-Fab autoantibodies were represented mainly by IgG and IgA isotypes but not IgM isotype. A direct correlation between the anti-Coxiella burnetii (anti-C.b.) antibody level and the anti-Fab IgG activity, and between the anti-C.b. antibody level and the anti-Fab IgA activity was found. In the group of vaccinees reacting strongly to the vaccine against Q fever, this correlation significantly increased for both the anti-Fab IgG and the anti-Fab IgA activities. No correlation was found with the sera in the group of the subjects that received placebo.

Diagnosis of strawberry vein banding virus by a non-radioactive probe.

Abstract: A non-radioactive digoxigenin-labelled cDNA probe was prepared from genomic DNA of American isolate No. 45058 of strawberry vein banding virus (SVBV). Five different air-dried SVBV-containing strawberry leaf samples originating from National Clonal Germplasm Repository, Corvallis, USA, reacted positively in dot blot hybridization with this probe. Six of twelve strawberry samples from the Czech Republic exhibiting symptoms of SVBV-like infection gave positive reaction with this probe. Our results confirm the spread of SVBV in Central Europe and introduce the first reliable screening method for this virus.

Immunogenicity of immunostimulating complexes of Japanese encephalitis virus in experimental animals.

Abstract: Immunogenicity of immunostimulating complexes (ISCOMs) of Japanese encephalitis virus (JEV) were studied in mice, rabbits and monkeys. Two doses of JE ISCOMs elicited a strong immune response in mice with an uniform distribution in IgG subclasses. Different time intervals between the two doses of ISCOMs led to similar titers of antibodies. Rabbits and monkeys immunized with ISCOMs developed strong neutralizing immune, response. Mice immunized with ISCOMs demonstrated cell-mediated immunity (CMI) as evidenced by T cell proliferation and macrophage migration inhibition (MMI) assays.

Interferon-omega suppresses hepatitis B surface antigen production in human hepatoma cell line.

Abstract: Biological activities of human interferon (IFN) omega are less well characterized than those of other type I human IFNs. We compared the ability of recombinant IFN-omega, IFN-alpha 2 and IFN-gamma to inhibit the production of viral hepatitis B surface antigen (HBsAg) in the human hepatoma cell line PLC/PRF/5. The results demonstrated that the capacity of IFN-omega to suppress the HBsAg synthesis was similar to that of IFN-alpha 2. The kinetics of the inhibitory effect of IFN-gamma differed from those of the two other IFNs.

Monoclonal antibody based differentiation of Coxiella burnetii isolates

Abstract: Isolates of Coxiella burnetii from different geographic regions in Europe, USA, Japan and Africa were compared in their binding properties to the monoclonal antibody (MoAb) 1/4/H directed against the lipopolysaccharide (LPS) of C. burnetii strain Priscilla. Immunoblot analysis and enzyme-linked immunosorbent assay (ELISA) revealed different binding patterns of C. burnetii isolates under study. Most of the isolates tested did react with MoAb 1/4/H. Only four of 20 groups of isolates and one isolate of an otherwise positively reacting group did not react with MoAb 1/4/H. The results indicate a significant variation of LPS structure of the C. burnetii isolates studied.