Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Neutralization Tests”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources
PubMed1996

A test for neutrality of mutations of the lacZ transgene.

Neutral mutations are stable alterations in DNA that are neither beneficial nor damaging to the cell. Once a mutation is fixed in the DNA, the mutant frequency should increase to its maximum and plateau thereafter, provided that enough expression time is given. Evidence has been obtained indicating neutrality for the endogenous Dlb-1 locus and for the lacl in the BigBlue transgenic system, and is reported here for lacZ in the Muta Mouse system. We have found that, after an acute dose of ethylnitrosourea (ENU, 250 mg/kg) the mutant frequency for both lacZ transgene and Dlb-1 remained constant between 10 and 70 days after mutagenesis in the small intestine, where cell turnover is rapid (approximately 7 days). The same concept should apply to other tissues.

Animals↗
PubMed1975

New human adenovirus isolated from a renal transplant recipient: description and characterization of candiate adenovirus type 34.

An antigenically distinct adenovirus is described which was isolated in March 1972 from the urine of a 17-year-old Caucasian male who was experiencing fever after receiving a kidney transplant from a cadaver in February. The adenovirus could not be isolated in April from a pharyngeal swab which yielded cytomegalovirus. Complement-fixation, hemagglutination-inhibition, and/or serum-neutralization tests on sequential serum specimens from the patient confirmed that the adenovirus infection occurred during March and showed that infections with cytomegalovirus and respiratory syncytial virus also occurred during late March and April. The patient's persistent fever, for which other causes could not be found, may have been associated with one or more of these infections. Upper respiratory symptoms and lung involvement were not found during this period. Mild liver dysfunction during this time could not be clearly related to adenovirus infection because of the presence of multiple other causes. The adenovirus may have been latent in the donor kidney and become active in the new host as a consequence of immunological impairment. The adenovirus, purified by terminal dilution and plaque procedures, has antigenic, morphological, biophysical, host susceptibility, and hemagglutinating properties characteristic of adenovirus group IA. Buoyant densities in CsCl are 1.340 g/ml for the virion, 1.304 g/ml for the group CF antigen (hexon), 1.295 g/ml for the major soluble complete hemagglutinin (dodecon), and 1.206 g/ml for the minor soluble complete hemagglutinin (tentatively, fiber dimer). The virus does not cross-react in reciprocal hemagglutination-inhibition and serum-neutralization tests with antisera to adenovirus types 1 to 33. We propose this virus as candidate adenovirus type 34 (Compton).

Adenoviridae↗
PubMedDate not supplied

Sylvatic transmission of arboviruses among Bornean orangutans.

Wild populations of nonhuman primates live in regions of sylvatic arbovirus transmission. To assess the status of arbovirus transmission in Bornean forests and the susceptibility of wild orangutans to arboviral infection, blood samples of wild orangutans, semi-captive orangutans, and humans were examined. Samples were tested by plaque reduction neutralization test for antibodies to viruses representing three families (Flaviviridae, Alphaviridae, and Bunyaviridae), including dengue-2, Japanese encephalitis, Zika, Langat, Tembusu, Sindbis, Chikungunya, and Batai viruses. Both wild and semi-captive orangutan groups as well as local human populations showed serologic evidence of arbovirus infection. The presence of neutralizing antibodies among wild orangutans strongly suggests the existence of sylvatic cycles for dengue, Japanese encephalitis, and sindbis viruses in North Borneo. The present study demonstrates that orangutans are susceptible to arboviralinfections in the wild, although the impact of arboviral infections on this endangered ape remain unknown.

Animals↗
PubMed2002

[Hematopoietic inhibitors elaborated by bone marrow endothelial cells].

UNLABELLED: In this study, the roles of hematopoietic inhibitors elaborated by bone marrow endothelial cells in the proliferation and differentiation of hematopoietic progenitors were investigated. Murine bone marrow endothelial cell conditioned medium (BMEC-CM) was collected and the components with > 10 kD and < 10 kD were obtained by centrifugal ultrafiltration. The effect of BMEC-CM and its components on proliferation of hematopoietic progenitors was evaluated by CFU-GM and HPP-CFC assay and antibody neutralization test. The expression of the inhibitors in BMEC and BMEC-CM was detected by RT-PCR and Western blot, and change of proliferation and differentiation-related genes during expansion of hematopoietic progenitors was examined by membrane hybridization technique. THE RESULTS: (1) When BME C-CM and its components directly were added to CFU-GM and HPP-CFC culture system, BMEC-CM had no effect on colony formation, > 10 kD component enhanced and < 10 kD component inhibited the formation of CFU-GM and HPP-CFC. (2) When BMEC-C M and its components were added to liquid culture system of marrow cells, after 24 hours incubation, CFU-GM decreased and HPP-CFC increased significantly in B MEC-CM group, CFU-GM increased and HPP-CFC had no significant change in > 10 kD component group; and both CFU-GM and HPP-CFC reduced in < 10 kD group. (3) MIP-2, MIP-1 alpha, MSP, TGF-beta, TNF-alpha, IFN-gamma and T beta 4 were expressed in murine marrow endothelial cells, and MIP-2, MIP-1 alpha, MSP, TGF-beta, TNF-alpha and T beta 4 were existed in BMEC-CM. (4) Antibody neutralization test results demonstrated that TGF-beta, MSP, MIP-1 alpha, IFN-gamma and T beta 4 existed in BMEC-CM had significant suppressive effects on CFU-GM and HPP-CFC. (5) T beta 4 combined with 5 hematopoietic cytokines (SCF, IL-3, IL-6, GM-CSF and EPO) added to CD34(+) cells expansion culture system, HPP-CFC significantly increased compared with 5 cytokines group. T beta 4 could downregulated the expression of proliferation and differentiation-related genes and signal transduction-related genes. It is concluded that BM EC-CM promotes the proliferation of early hematopoietic progenitor cells, and this effect is related with the inhibitors existed in BMEC-CM and it could be executed via influencing cell proliferation and differentiation-related genes and signal-related genes.

Animals↗
PubMedDate not supplied

Evaluation of an enzyme-linked immunosorbent assay for quantitation of antibodies to Junin virus in human sera.

An enzyme-linked immunosorbent assay (ELISA) was evaluated for the quantitation of anti-Junin virus (JV) antibodies, in 83 selected cases of Argentine haemorrhagic fever (AHF). Serum samples were studied in two groups to facilitate comparative analysis; the first group was ELISA with indirect immunofluorescence (IF) test, in the second ELISA with plaque reduction neutralization test (PRINT). From the results obtained by using ELISA and IF on the same serum samples, a clear tendency of ELISA to demonstrate seroconversion for JV earlier and at higher frequency than IF test was noted. Simultaneous titration of specific antibodies by ELISA and PRNT tests rendered significantly correlated titers (r = 0.81), both methods being equivalently specific (100%). The demonstration of specific antibodies by ELISA in two cases that were undetected by the PRNT test resulted in a higher sensitivity index for ELISA than for PRNT (100% vs 97%). It is concluded that ELISA could efficiently replace IF and PRNT tests for the diagnosis of AHF.

Antibodies, Viral↗
PubMed2003

Antibody response after RSV infection in children younger than 1 year of age living in a rural area of Mozambique.

Serological responses have been studied in respiratory syncytial virus (RSV) infected children < 1 year of age attending the outpatient department of the Manhiça District Hospital (Mozambique). Molecular characterization of viral RNA in nasopharyngeal aspirates from the infected children indicated a high level of genetic uniformity among the infecting viruses, all of which belonged to a single genotype of RSV group A. A representative virus strain, Moz00, was isolated from one of the infants and was used, together with the group A strain A2 and the group B strain 8/60, as antigens in the quantification of infant antibody responses. In this study, 97.5% (39/40) and 96.4% (27/28) of infected children produced an antibody response against Moz00 detected by the membrane fluorescent antibody test (MFAT) and the neutralization test (NT), respectively. Seroconversion rates decreased when the A2 and 8/60 strains were used as antigen in MFAT (95.4% and 88.2%, respectively) or NT (81.8% and 54.5%, respectively), indicating that antibody responses had both group- and strain-specific components. Antibodies in convalescent sera of infected children were compared with maternally derived antibodies detected in a group of children also < 1 year of age, but with no evidence of RSV infection. The convalescent sera exhibited reduced neutralizing capacity when the 8/60 strain was used as antigen (P = 0.028), suggesting that the infant antibody response lacks neutralizing capacity against strains of the heterologous virus group. Restricted cross-reactivity and neutralizing capacity of antibodies generated by young children might be expected to induce only moderate protection in subsequent epidemics against genetically distant strains.

Amino Acid Sequence↗
PubMed1983

Rapid test for detection of rabies antibodies in human serum.

A simple, sensitive, rapid method based on the principle of immunoadherence hemagglutination (IAHA) has been devised for the detection of rabies antibody. In this test, fixation of complement to complexes of rabies antigen with specific antibodies is readily detected by agglutination of human erythrocytes bearing receptors for C3. Sera from individuals undergoing preexposure rabies immunization were tested for rabies antibodies by the IAHA method and by a virus neutralization test performed in tissue culture, the rapid fluorescent focus inhibition test. IAHA titers showed a high degree of correlation with rapid fluorescent focus inhibition test titers, although it is not known whether results of the IAHA test represent the detection of neutralizing antibodies. An advantage of the IAHA test over the rapid fluorescent focus inhibition test was that results were obtained in a shorter period of time. In some instances, this can be of clinical significance in determining antibody levels to rabies virus. Furthermore, the IAHA test is most applicable as a rapid screening tool for the detection and quantitation of rabies antibodies in vaccinated subjects.

Antibodies, Viral↗
PubMed1989

Reactivity of VP4-specific monoclonal antibodies to a serotype 4 porcine rotavirus with distinct serotypes of human (symptomatic and asymptomatic) and animal rotaviruses.

Thirteen hybridomas secreting VP4-specific monoclonal antibodies against the Gottfried strain of porcine rotavirus (serotype 4) were produced and characterized. Nine of the hybridomas secreted neutralizing monoclonal antibodies (N-MAbs) against Gottfried rotavirus. These N-MAbs were divided into five distinct groups (groups I to V) according to their patterns of reactivity with different serotypes of human and animal rotaviruses. Group I N-MAbs (n = 3) were cross-reactive with five different serotypes of human rotavirus examined by a plaque reduction virus neutralization test. Group II N-MAbs (n = 3) neutralized all symptomatic human rotavirus serotypes tested and asymptomatic human rotavirus serotype 4 to a low titer. The single group III N-MAb neutralized mainly symptomatic human rotavirus serotypes 2 and 9 and none of the asymptomatic human rotavirus serotypes. The one N-MAb in group IV reacted at low titers with only asymptomatic human rotavirus serotypes 1 through 4. A group V N-MAb recognized serotype 4 porcine rotaviruses (Gottfried and SB-2) but no other human or animal rotaviruses examined. None of the N-MAbs recognized any animal rotaviruses tested (SA-11, RRV, OSU, NCDV, and B223), except for the Gottfried and SB-2 rotaviruses. The failure of N-MAbs (groups I to IV) to react with any animal rotaviruses tested but their ability to react variably with all human rotaviruses tested suggest that neutralizing epitopes on the VP4 protein are highly conserved between the Gottfried porcine and human rotaviruses. The Gottfried rotavirus may possibly represent a naturally occurring reassortant between pig and human rotaviruses or a rotavirus which is human in origin but pathogenic for swine.

Animals↗
PubMed1985

Erythropoietin production by macrophages in the regenerating liver.

The site of erythropoietin (Ep) production and/or storage in the rat liver was determined. A guinea pig anti-Ep was produced against purified rat Ep (64,096 +/- 4j064 IU/mg). This antibody was found to be highly specific using rocket immunoelectrophoresis, Ouchterlony gel diffusion methods, and immunoprecipitin reactions as well as Ep neutralization tests (capable of completely neutralizing up to 2,000 IU Ep/mg). This anti-Ep was labeled with either fluorescein for light microscopic study or ferritin for electron microscopy. Kupffer cells showed varying degrees of labeling after hepatectomy alone or hepatectomy combined with nephrectomy and/or hypoxia. Greatest labeling was seen in Kupffer cells of rats that were nephrectomized 48 hr posthepatectomy and kept at ambient pressure. No labeling of hepatocytes or vascular and bile duct endothelium was noted.

Animals↗
PubMed1986

Hemagglutination with ovine rotavirus. Brief report.

The virus was grown in MA 104 cells, a stable cell line derived from embryonic rhesus monkey kidney, and tested for hemagglutination (HA) with erythrocytes of a variety of species at 4 degrees C, room temperature and 37 degrees C. HA was observed at all temperatures with chicken, sheep, rabbit, guinea pig and human erythrocytes but not with horse, cattle, goat, swine and goose erythrocytes. HA reaction was inhibited by specific antiserum. Some factors involved in the HA and HA-inhibition (HI) were investigated and standard HA and HI tests were worked out. The HI test as well as neutralization test clearly distinguished ovine rotavirus from bovine, human, simian, equine, porcine and lapine rotaviruses.

Animals↗
PubMed1983

Enzyme-linked immunosorbent assay (ELISA) for antibodies to Clostridium difficile toxins in patients with pseudomembranous colitis and antibiotic-associated diarrhoea.

Enzyme-linked immunosorbent assay (ELISA) was established with purified toxins from Clostridium difficile as antigen to measure antibody response in patients with pseudomembranous colitis (PMC) and prolonged antibiotic-associated diarrhoea (AAD). Positive ELISA titres were defined in a control population. Antibodies of IgG class against toxin B were demonstrated in 6/88 (7%) control sera and in 31/61 (51%) sera from 11/19 (58%) patients. Antibodies of IgA class were found in one patient while antibodies of IgM class were not demonstrated. ELISA antibodies against toxin A were not demonstrated. For comparison a neutralization test was performed and neutralizing antibodies to toxin B but not to toxin A were demonstrated in 10/61 (16%) sera from 4/19 (21%) patients and in none of the controls. ELISA was found to be a more sensitive assay than neutralization. ELISA antibodies were detected from the third week of the disease while neutralizing antibodies appeared after 5 weeks. Lack of an antibody response in ELISA seemed to correlate to a more severe colitis.

Anti-Bacterial Agents↗
PubMed2000

Genetic diversity of hantaviruses associated with hemorrhagic fever with renal syndrome in the far east of Russia.

To identify the hantaviruses causing hemorrhagic fever with renal syndrome (HFRS) in the Far East of Russia, blood samples collected from HFRS patients in 1994-1998, were examined by reverse transcription-polymerase chain reaction. In addition, 36 sera were tested by an immunofluorescence assay for antibodies against Hantaan, Seoul, Puumala, and Khabarovsk viruses, and 54 samples were tested by plaque reduction neutralization test. With both serological assays, the highest antibody titers were to Hantaan and/or Seoul viruses. Of 110 blood samples 36 were found RT-PCR positive. Phylogenetic analysis the sequences of a 256-nucleotide (nt) fragment of the hantavirus M genome segment revealed at least 3 genetically distinct hantavirus lineages. Nucleotide sequence comparison showed that two of the lineages, designated as FE and Amur (AMR), differed from one another by 15.9-21.2% and from Hantaan virus by 9.8-17.5%. The third lineage, VDV, differed from Seoul virus by 2.6-5.1%. All S segment sequences were from FE lineage, and differed from Hantaan virus by 10.7-12.6%. Thirty of the 36 (83%) analyzed sequences were found to be the FE genotype, which is very similar to that of Hantaan virus, strain 76-118. Of the remaining hantaviruses, 11% were the AMR genotype, and 6% the VDV genotype, which are genetically novel genotypes of Hantaan or Seoul viruses, respectively.

Amino Acid Sequence↗
PubMed2004

Partial antigenic characterization of buffalopox virus.

The present study was undertaken to antigenically characterize the buffalopox virus (BPV). Six monoclonal antibodies (MAbs) against the BP4 strain of BPV have been produced and characterized. All six MAbs appeared to be specific to BPV, as none of them showed cross-reactivity with other poxviruses in antigen capture ELISA. Only two MAbs (20AB8 and 20CD11) bound significantly with different BPV isolates in antigen capture ELISA, whereas the remaining four MAbs bound weakly with the BPV. In Western blot analysis with purified BPV-BP4, the rabbit hyperimmune serum against purified BPV-BP4 reacted with 15 immunodominant polypeptides (100 kDa to 25 kDa), whereas two MAbs (21CB6, 21DB11) reacted with 42 kDa and 45 kDa polypeptides, respectively. However, three MAbs (20AB8, 20CD11, 21CB5) reacted with three degraded polypeptides (100 kDa, 40 kDa and 87 kDa) of BPV-BP4. In radioimmunoprecipitation assay (RIPA) with the rabbit hyperimmune serum to BPV-BP4, three virus specific polypeptides (69 kDa, 34 kDa, 32 kDa) were recognized in BPV-BP4, whereas two polypeptides (69 kDa, 34 kDa) were recognized in other BPV isolates (BPV-Bly, BPV-Vij96, BPV-Vij97). In virus neutralization test, none of the six MAbs tested showed any significant neutralizing ability to infection with different BPV isolates. However, the hyperimmune serum showed weak neutralizing ability to BPV infection.

Animals↗
PubMed2002

Testing the neutral theory of molecular evolution with genomic data from Drosophila.

Although positive selection has been detected in many genes, its overall contribution to protein evolution is debatable. If the bulk of molecular evolution is neutral, then the ratio of amino-acid (A) to synonymous (S) polymorphism should, on average, equal that of divergence. A comparison of the A/S ratio of polymorphism in Drosophila melanogaster with that of divergence from Drosophila simulans shows that the A/S ratio of divergence is twice as high---a difference that is often attributed to positive selection. But an increase in selective constraint owing to an increase in effective population size could also explain this observation, and, if so, all genes should be affected similarly. Here we show that the difference between polymorphism and divergence is limited to only a fraction of the genes, which are also evolving more rapidly, and this implies that positive selection is responsible. A higher A/S ratio of divergence than of polymorphism is also observed in other species, which suggests a rate of adaptive evolution that is far higher than permitted by the neutral theory of molecular evolution.

Animals↗