Middlebrook-Dubos neutral red test in Mycobacterium tuberculosis treated by cerase.
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Antitubercular Agents↗
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Serological classification and typing of Clostridium botulinum.
Serological classification of Cl. botulinum, based on the antigenic structure of the toxins produced, is distinguished by the behaviour of the toxin-antitoxin mixtures in in vivo neutralization tests. Observations on the dissimilarity between strains within types, the behaviour of antitoxins in the cross-neutralization tests, the established concepts of the antigenic structure of the toxin types and the lack of a standard methodology for typing, have led to the definition of the terms efficiency, type, subtype, intratypic serological variant (ISV), and degree of serological homology. These definitions are primarily applied to typing and to the establishment of the taxonomic serological categories of type, subtype and ISV. In the case of antitoxin standardization, the accepted standard methods must be followed.
Clostridium botulinum↗
Heparin neutralizing activity test in the diagnosis of acute myocardial infarction.
We have previously shown in patients after recovery from a myocardial infarct (post-MI) that the heparin neutralizing activity (HNA) in the plasma is raised and that this activity may come from platelet factor 4 derived from activated platelets. This report concerns 89 patients admitted with acute chest pain; in 54, with evidence of acute infarction, the level of HNA is much higher than in a post-MI group or controls. Over the ensuing weeks the HNA decreases to the post-MI level. In 34 patients the evidence subsequently collected excluded a diagnosis of infarction; in these there were almost always normal amounts of HNA and little overlap with the results from the patients with infarcts. This easy test is therefore likely to prove clinically useful. Its significance is discussed. The platelet count and platelet volume are both abnormal in patients with acute infarction and also in the chest pain group so these tests do not help to discriminate.
Acute Disease↗
Serological relationships among genotypic variants of betanodavirus.
Betanodaviruses, the causative agents of viral nervous necrosis or viral encephalopathy and retinopathy, are divided into 4 genotypes based on the coat protein gene (RNA2). In the present study, serological relationships among betanodavirus genotypic variants were examined by virus neutralization tests using rabbit antisera raised against purified virions of strains representative of each genotype. All 20 isolates examined shared epitopes for neutralizing, but they fell into 3 major serotypes (A, B, C). This sero-grouping is in part consistent with their genotypes, i.e. Serotype A for striped jack nervous necrosis virus (SJNNV) genotype, Serotype B for tiger puffer nervous necrosis virus (TPNNV) genotype, and Serotype C for both redspotted grouper nervous necrosis virus (RGNNV) and barfin flounder nervous necrosis virus (BFNNV) genotypes. The serological relatedness between RGNNV and BFNNV genotypes may result from their relatively higher similarity in RNA2 sequences. In neutralization tests using antisera of kelp grouper Epinephelus moara, which were raised against recombinant coat proteins representing each genotype, anti-SJNNV and anti-TPNNV sera neutralized only the homologous strain, and anti-RGNNV and anti-BFNNV sera reacted with both RGNNV and BFNNV strains. The present serological findings will be important in investigating the infectivity and host-specificity of betanodaviruses and in developing vaccines for the disease.
Amino Acid Sequence↗
Seroepidemiological and ecological studies of the adenovirus-associated satellite viruses.
The seroepidemiology of the defective adenovirus-associated satellite viruses was studied by use of a neutralization test that has been shown to be much more sensitive than the complement-fixation (CF) test. Less than 25% of the subjects in any age group were positive for any type of satellite virus CF antibody. The neutralization test revealed serological evidence of satellite infection in almost 80% of the subjects in some age groups. Studies of geometric mean antibody titers by neutralization showed that antibody against type 1 and the type 2-3 complex reached peak levels at 2 to 3 years of age; antibody against types 2 and 3 reached mean titers of 500 to 800, whereas mean antibody levels of only 200 were found for type 1. Type 4 antibodies were rarely noted in human sera. In a companion study in monkeys, monospecific responses to types 1 and 4 were found only in rhesus and green monkey sera, respectively. These data suggest that the type 2-3 complex may be the only naturally occurring satellite serotype which infects man and that antibodies noted against types 1 and 4 may be the result of cross-reactions. No satellite viruses were isolated from throat or rectal swabs of 100 children between 6 months and 3 years of age. However, the patterns of adenovirus and enterovirus isolations from these specimens were typical of previous studies in this laboratory.
Journal Article↗
Antibody nature of circulating inhibitor of plasma von Willebrand factor.
A circulating plasma inhibitor of the "von Willebrand factor" was observed in a multiply tranfused subject with severe von Willebrand's disease. The platelet-active von Willebrand factor is associated with a plasma protein macromolecular complex that is deficient in the disease. The inhibitor appears to be an IgG antibody, kappa type, based on neutralization tests with goat antisera to specific human immunoglobulins. The IgG and inhibitor separated out together in plasma fractions obtained by "salting-out" and chromatographic procedures. Two separate inhibitor neutralization tests for the platelet-active factor, one with human plasma and ristocetin, the other with bovine plasma, gave similar results, based on the macroscopic aggregation time test of fixed human platelets. With cryoprecipitate transfusions the inhibitor was transiently neutralized with the temporary appearance of von Willebrand factor, factor VIII, and factor VIII-like antigen in the plasma. The plasma inhibitor level increased after transfusion, suggesting an anamnestic response. Lower titer inhibitor plasmas neutralized only the platelet activity. Highest titer plasma also neutralized human factor VIII, but only in part; it did not neutralize either bovine factor VIII or the human small active factor VIII fragment. The anti-factor VIII activity of the von Willebrand factor inhibitor may be due to steric hindrance, dependent on the spatial relationship of factor VIII sites on the macromolecular complex.
Animals↗
Micro indirect hemagglutination test for Cytomegalovirus.
In an effort to obtain the flexibility and ease of performance of a rapid, serological test for detection of cytomegalovirus antibody, the indirect hemagglutination (IHA) technique was investigated by using a microserological system. Antigens were prepared from tissue cultures of infected human fibroblasts. The specificity of the cytomegalovirus antibody response detected by the IHA test correlated well with the standard neutralization test. The IHA method was more sensitive than the complement fixation test in detecting antibody in congenitally infected newborns. There appeared to be some heterologous antibody response with Herpesvirus hominis or varicella virus infections. The IHA test pattern was found to be very stable with excellent persistence of agglutination.
Antigen-Antibody Reactions↗
[New subtype of coltivirus isolated from mosquitoes in the northeast part of China].
OBJECTIVE: The purpose of this study was to isolate new arbovirus from mosquitoes collected from the northeast part of China during the summer of 1996. METHODS: The cell used for isolation were C6/36 and BHK-21 cells. RESULTS: Two strains (NE97-12 and NE97-31) of coltivirus were isolated among 68 mosquito specimens. The viruses caused cytopathogenic effects on C6/36 cell, but not on BHK-21 cells. They were resistant to both 5-IDU and ether, but sensitive to pH3.0 and temperature at 56 degrees C for 30 minutes. IFA of new isolates with mouse ascitic fluid anti-coltivirus TRT2 strain showed positive reaction. Polyacrylamide gel electrophoresis (PAGE) of two isolates showed 12 segments of double-stranded(ds) RNA and PAGE profiles were 6-5-1, which were different from that of coltivirus TRT2 strain(6-6). There was no cross neutralization between new isolates and TRT2 strain by tissue culture cross-neutralization test. CONCLUSION: The results indicated while new isolates were serologically related to TRT2 strain of coltivirus by IFA, the neutralization test suggests that it represents a distinct serotype. These new isolates isolated firstly from the northeast part of China belong to a new subtype of coltivirus.
Animals↗
Field trial to evaluate immunogenicity of a glycoprotein I (gE)-deleted pseudorabies virus vaccine after its administration in the presence of maternal antibodies.
A field trial was conducted on a commercial swine farm quarantined because of infection with pseudorabies virus. The purpose was to investigate, in growing pigs born to hyperimmunized sows, the immunogenicity of a vaccine with a glycoprotein I (gE) deletion. One hundred twenty pigs were assigned at random to 1 of 3 vaccination schedules at ages: 8 and 12 weeks; 8, 12, and 14 weeks; and 8, 12, and 16 weeks. Immune response was measured at 8, 12, 14, 16, and 18 weeks, using the serum neutralization test, a screening ELISA, and assays of IgG and IgA in serum and nasal secretions. Results of the serum neutralization test and the screening ELISA indicated that, for pigs vaccinated only at 8 and 12 weeks, the percentage of pigs with pseudorabies virus serum antibodies decreased substantially by 18 weeks; for pigs given a booster at 14 or 16 weeks, the prevalence of serum antibodies at 18 weeks was higher, with 16-week booster vaccination eliciting the best response. At each age, nasal IgA and IgG values were highly correlated (r > or = 0.70), as were serum IgA and IgG values; correlations of serum with nasal IgA and IgG values were somewhat lower (approx range, r = 0.40 to 0.70). Nevertheless, an increase in serum IgA or IgG values on vaccination was no guarantee of an increase in nasal IgA or IgG values. For serum and nasal mucosal antibodies, a poor immune response was associated with high quantities of maternally derived antibodies. Vaccination at 16 weeks was necessary to ensure eliciting of an immune response in almost all pigs.
Aging↗
An analysis of the properties of monoclonal antibodies directed to epitopes on influenza virus hemagglutinin.
Monoclonal antibodies (MAbs) specific for the hemagglutinin (HA) of the H3 subtype of influenza A virus were grouped according to their inability to bind to particular MAb-selected neutralization escape mutants of the virus having an amino acid substitution in one of the five postulated antigenic sites on the molecule. Additional residues critical to the binding of the MAbs were deduced from their patterns of reactivity with a panel of field strains and receptor mutants of the H3 subtype. The relationship of these residues to the actual epitopes recognized by the MAbs was inferred from their location on the three-dimensional structure of the HA molecule. In this way it was generally possible to identify a number of residues that are critical to the integrity of the epitope recognized by each of the MAbs examined. It was found that: (1) Several of these epitopes appear to be discontinuous and some may depend on residues contributed by more than one monomer. For example, residue 205, in the interface between monomers of the HA, was found to affect the integrity of the epitopes for several MAbs, possibly by stabilizing the conformation of residues around the receptor-binding pocket and/or in site B on the adjacent monomer. The activity of these particular MAbs was greatly decreased if the virus was exposed to pH 5. (2) All the MAbs tested neutralized viral infectivity and inhibited hemagglutination, although the single MAb directed to site C, which is the most distant from the receptor-binding site, was the least efficient. (3) Hemagglutination inhibition, and particularly neutralization tests, were more discriminating than ELISA in discerning subtle differences between the corresponding epitopes recognized by MAbs on different field strains. (4) Efficiency of neutralization of infectivity did not correlate consistently with hemagglutination inhibiting efficiency; MAbs postulated to bind to epitopes close to the receptor-binding pocket were very efficient at inhibiting hemagglutination, whereas neutralization efficiency tended to be more influenced by the affinity of binding of the MAb. (5) A MAb binding to any particular epitope could affect the binding of a second MAb directed to an epitope within the same or even a different antigenic site. The observed effect was most commonly inhibition of binding, which was not always reciprocal; enhancement of binding was also observed with certain combinations of MAbs. The relative affinity of the MAbs, in addition to steric constraints, were shown to be important factors in the ability to compete for interaction with HA.
Amino Acid Sequence↗
Neutralizing epitopes of feline calicivirus.
A new collection of eighteen neutralizing monoclonal antibodies (N-MoAbs), raised against feline calicivirus (FCV), was used to analyze neutralizing epitopes of the F4 strain of FCV, the prototype strain of FCV in Japan. By cross-neutralization tests with the 20 FCV strains including Japanese. American, Swiss, and New Zealand isolates, the 18 N-MoAbs were categorized into six groups. One N-MoAb (1 D 7) neutralized all the strains tested: eight N-MoAbs neutralized only FCV-F 4; while the others neutralized the FCV strains in various degrees. In order to confirm this grouping, eight N-MoAbs were used to select neutralization-resistant variants of FCV F4. Although no variant against 1 D 7 was obtained, antigenic variants against other N-MoAbs were obtained. Neutralization tests using these variants revealed that there are six neutralizing epitopes on FCV F4 and that several epitopes are functionally related. One of these epitopes was the same epitope as one of the two epitopes identified by another panel of N-MoAbs we produced previously. Therefore, a total of seven neutralizing epitopes on FCV F4 were identified. Immunoblot analysis indicated that four of the seven epitopes existed on the 67 kDa capsid protein of the virus.
Animals↗
A radioimmunoassay for tetanus antibodies using protein A - containing Staphylococcus aureus.
To measure tetanus antibodies a trace amount of 125I-labeled tetanus toxin is mixed with appropriate dilutions of human serum or blood. The labeled antigen-antibody complexes are adsorbed to heat-killed staphylococci (Cowan I) via their surface protein A. The radioactivity of the washed solid phase is a function of the initial antibody concentration. The test allows the measurement of 6 X 10(-0) U of tetanus antitoxin in a volume of 0.03 ml. In order to avoid possible interferences, serum has to be diluted 20-fold before use. Taking that into account, the real border limit of sensitivity is 4 X 10(-3) U/ml serum. Antibodies may be measured in serum, in plasma, and even in heparinized blood. As to its sensitivity, the test compares well with the toxin neutralization procedure. It is superior to the previous radioimmunologic, enzymoimmunologic, and hemagglutination techniques with respect to sensitivity and reproducibility. It reflects the values obtained in the toxin neutralization test better than the other in vitro procedures, as shown by parallel assays of 17 sera.
Humans↗
Detection of antibodies to hepatitis C virus in blood donors and their relationship to surrogate markers.
Stored serum samples from 7,179 nonselected blood donors were tested for anti-HCV using Ortho EIA first generation. Results were compared to data acquired by anti-HBc testing and ALT levels found in routine testing. 24 donors (0.33%) were repeatedly reactive with Ortho HCV EIA, 230 (3.20%) were anti-HBc-positive and 138 (1.92%) had raised ALT levels > or = 36 IU/l. A low correlation was found between HCV antibody screening with EIA and surrogate testing. When tested in addition with the Abbott HCV EIA, 20 of the 24 Ortho EIA-positive subjects showed a positive reaction. In the Abbott neutralization test 13 of these 20 (65%) were reactive. 8 (33.33%) of the 24 Ortho-EIA-positive donors were positive in the two-antigen-RIBA (first generation), 8 were indeterminate and 8 were nonreactive. The neutralization test and the RIBA can be used as supplementary tests fo further analyze HCV-EIA-positive specimens.
Blood Banks↗
[Serological and virological diagnosis for dengue infection].
For many years dengue fever has been one of the most serious diseases in southeast Asia. A dengue type 2 epidemic occurred in Liuchiu, Pingtung in 1981. A recent epidemic, primarily of dengue type 1 has been in progress in southern Taiwan since 1987. In clinical aspects, dengue infection may be confused with measles, rubella, influenza, acute mumps, enteric viral infection and food allergies. Only definite confirmation is possible through serological and virological methods. All four serotypes of the dengue virus, however, are antigenically similar, and their antibodies are also cross-reactive with other flaviviruses. This phenomenom renders the specificity of many serological tests to be less accurate than they should be. Thus, improved virus isolation and identification becomes a necessary tool in proving the dengue infection. This article offers a brief review of some serological tests including the hemagglutination inhibition test, IgG- and MAC-ELISA, the plaque reduction neutralization test, and virological tests including antigen capture ELISA and indirect immunofluorescence antibody assay, with emphasis on their application to the diagnosis of dengue infection.
Antibodies, Viral↗
Isolations of Cache Valley virus in Texas, 1981.
Two strains of the same virus (isolates AR 168 and 7856), were isolated in 1981 from an apparently healthy cow and a sick sheep in TX, U.S.A. These isolates were shown to be members of the Bunyamwera serogroup (family Bunyaviridae, genus Bunyavirus) by complement-fixation tests. Serum dilution-plaque reduction neutralization test results indicated that the isolates are closely related to Cache Valley virus. The virus isolates were characterized by sensitivity to lipid solvent, size (50-100 nm by filtration and 70 nm by electron microscopy), heat (56 degrees C) and pH 3 lability, cytopathic effects or plaques in cultures of Vero, LLC-MK2, embryonic bovine testicle and PS cells, and pathogenicity for suckling and weaned mice by the intracranial but not the intraperitoneal route. Gnotobiotic and conventional sheep and goats were experimentally infected by inoculation with one of the isolates given either intravenously or intraperitoneally. Elevation of body temperature, depression, tremors, muscle spasms, disorientation, feeding anomalies, convulsions, or other signs of central nervous system disturbances were observed.
Animals↗
Monitoring of classical swine fever in wild boar (Sus scrofa) in Slovenia.
Classical swine fever (CSF) is a highly contagious multi-systemic haemorrhagic viral disease of pigs. Not only domestic pigs, but also wild boar appear to play a crucial role in the epidemiology of CSF. Spleen (n = 739) and blood coagulum (n = 562) sampled from wild boars (Sus scrofa) shot in 2002, and serum samples from 746 wild boar shot in 2003 and 2004, were tested throughout Slovenia. In 2002, 17 samples were positive on enzyme-linked immunosorbent assay (ELISA) test for antibodies against classical swine fever virus (CSFV). Positive ELISA test was confirmed by a virus neutralization test. All other samples were negative. This is the first report that describes the epidemiology of CSFV from 2002 on, and the monitoring of the wild boar population in Slovenia at present.
Animals↗
Pseudorabies virus antibodies in swine slaughtered in Iowa.
Sera from butcher swine (1,246 total) were evaluated qualitatively by the microimmunodiffusion test and quantitatively by the virus neutralization test for antibody to pseudorabies virus. Ten percent of the sera had antibody to pseudorabies virus. Follow-up contact with veterinarians whose clients included the farms from which the positive swine originated revealed that few feeder swine are vaccinated against pseudorabies and that most infections with pseudorabies virus are subclinical.
Abattoirs↗
Statistical tests of neutrality of mutations.
Mutations in the genealogy of the sequences in a random sample from a population can be classified as external and internal. External mutations are mutations that occurred in the external branches and internal mutations are mutations that occurred in the internal branches of the genealogy. Under the assumption of selective neutrality, the expected number of external mutations is equal to theta = 4Ne mu, where Ne is the effective population size and mu is the rate of mutation per gene per generation. Interestingly, this expectation is independent of the sample size. The number of external mutations is likely to deviate from its neutral expectation when there is selection while the number of internal mutations is less affected by the presence of selection. Statistical properties of the numbers of external mutations and of internal mutations are studied and their relationships to two commonly used estimates of theta are derived. From these properties, several new statistical tests based on a random sample of DNA sequences from the population are developed for testing the hypothesis that all mutations at a locus are neutral.
Analysis of Variance↗