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 919 records · Page 51Linked to original sources
PubMed1982

Lanthony's new color test. IV. Neutral zone and neutral grays.

The classification of neutral grays is helpful for the differential diagnosis of color vision defects, especially when anomaloscopic examination is not possible. In congenital color vision defects the PR, RP region of the spectrum appears 'dark' to protan-defective subjects and 'light' to deutan-defective subjects. Acquired color vision defects have a common base type, the type III blue-yellow defect. The defect develops depending on the site of the primary lesion and also on the fixation mode. Classification of neutral grays may help in differentiating optic nerve diseases from retinal diseases; when visual functions become mediated by rods, sensitivity shifts and the BV, B region of the spectrum will appear relatively 'light' to the patient.

Color Perception Tests↗
PubMed1988

BK virus infection in patients with AIDS.

Antibodies to the human papovavirus BK (BKV) were determined in a group of 25 homo- and bisexual males with AIDS, 24 men with AIDS-related complex (ARC) and 18 healthy male homosexual controls from Copenhagen. The AIDS patients had a significantly lower prevalence and level of anti-BKV antibodies tested by IgG-ELISA, hemagglutination inhibition and neutralization tests than the ARC patients. About half of the anti-BKV antibody positive AIDS patients demonstrated primary infections or reactivations but without specific IgM production. The titers were low compared to primary infections in children. At least 2 of the patients lost their serological markers in the late phase of the disease. It is therefore possible that the low prevalence of BKV infection in AIDS patients is caused by loss of serological markers even if the level of total IgG is normal or increased.

AIDS-Related Complex↗
PubMed1985

[Measurement of the in vitro immune response of live attenuated measles virus vaccine and antibody levels in 0 to 10-year-old children].

The present study was carried out in order to test the antigenic effectiveness of the live attenuated meales vaccine which is routinly employed in our country. Sera obtained from 11 children before and after measles vaccination were tested for measles antibodies by complement fixation and neutralization tests. Sera samples were also collected from 0-10 years old children with history of vaccination, passed measles infection and none at all. These sera were also tested for measles antibody by complement fixation test. Virus isolation and seroconversion studies in children who were admitted to the outpatient clinics of Hacettepe hospital is also presented in this communication.

Antibodies, Viral↗
PubMed2004

Molecular evolution of microcephalin, a gene determining human brain size.

Microcephalin gene is one of the major players in regulating human brain development. It was reported that truncated mutations in this gene can cause primary microcephaly in humans with a brain size comparable with that of early hominids. We studied the molecular evolution of microcephalin by sequencing the coding region of microcephalin gene in humans and 12 representative non-human primate species covering great apes, lesser apes, Old World monkeys and New World monkeys. Our results showed that microcephalin is highly polymorphic in human populations. We observed 22 substitutions in the coding region of microcephalin gene in human populations, with 15 of them causing amino acid changes. The neutrality tests and phylogenetic analysis indicated that the rich sequence variations of microcephalin in humans are likely caused by the combination of recent population expansion and Darwinian positive selection. The synonymous/non-synonymous analyses in primates revealed positive selection on microcephalin during the origin of the last common ancestor of humans and great apes, which coincides with the drastic brain enlargement from lesser apes to great apes. The codon-based neutrality test also indicated the signal of positive selection on five individual amino acid sites of microcephalin, which may contribute to brain enlargement during primate evolution and human origin.

Amino Acid Sequence↗
PubMed1979

Quantification of tetanus antitoxin in human sera. I. Counter-immunoelectrophoresis.

An extensive sero-epidemiological survey of immunity to tetanus is to be performed in Norway during 1978 and 1979 and thus a simple and reliable method for screening sera for content of tetanus antitoxin is needed. An improved counter-immunoelectrophoretic method for quantification of tetanus antitoxin is described. The toxin neutralization test in mice is considered to correlate well with protection in humans. Counter-immunoelectrophoresis has the advantage of using tetanus toxoid instead of toxin as well as being more rapid and less expensive. Specific antibodies of the IgG, IgM, and IgA classes could be read simultaneously for many sera. This may be of importance, since it is reported in the literature that only antibody of the IgG class is capable of neutralizing tetanus toxin in mice. Counter-immunoelectrophoresis is limited by being less sensitive than the toxin neutralization test in mice.

Chromatography, Gel↗
PubMed2004

Construction of yellow fever/St. Louis encephalitis chimeric virus and the use of chimeras as a diagnostic tool.

St. Louis encephalitis (SLE) and West Nile (WN) flaviviruses are genetically closely related and cocirculate in the United States. Virus neutralization tests provide the most specific means for serodiagnosis of infections with these viruses. However, use of wild-type SLE and WN viral strains for laboratory testing is constrained by the biocontainment requirements. We constructed two highly attenuated yellow fever (YF) virus chimeras that contain the premembrane-envelope (prM-E) protein genes from the virulent MSI-7 (isolated in the United States) or the naturally attenuated CorAn9124 (Argentina) SLE strains. The YF/SLE (CorAn version) virus and the previously constructed YF/WN chimera were shown to specifically distinguish between confirmed human SLE and WN cases in a virus neutralization test using patient sera. These chimeras have the potential for use as diagnostic reagents and vaccines against SLE and WN.

Amino Acid Sequence↗
PubMed1965

Asian influenza in 1963 in two general practices in Cambridge, England.

A clinical, epidemiological and virological investigation was conducted on patients in two general practices in Cambridge, England, during an influenza epidemic between February and April 1963. The epidemiological pattern differed from that of the 1957-58 Asian influenza epidemic in that the overall incidence was considerably lower (3.2%) and that the highest attack rates were not in school children but in pre-school children (71.5 per 1000 persons).Virological investigation confirmed the diagnosis of Influenza A2 infection in 56 of 63 patients (89%). Isolations were made in 29 of 51 specimens tested. Serological studies revealed that the complement fixation test was more reliable than hemagglutination - inhibition or neutralization tests. Clinical features resembled those reported in previous epidemics, cough, headache and limb pains being prominent features.

Adolescent↗
PubMed1981

[The latex-IgM-test in virus diagnostic: determination of cytomegalovirus antibodies (author's transl)].

We examined the practical value of the Latex-IgM-test in diagnostic virology. Sera of patients suspected to have a cytomegalic infection were used for serological investigation. Cytomegalovirus produced in cell cultures was incubated with serum from patients. The resulting virus-antibody complex was removed by centrifugation and sensibilized Latex particles were added (anti IgG and anti IgM). The quantity and type of the bound antibody could be determined in this way. The sera were checked by parallel determination by another reliable method, the neutralization test. Immunoglobulins G and M separated and tested for antibodies. The usefulness of the Latex-IgM test for the routine diagnostics could be evaluated in the present study.

Antibodies, Viral↗
PubMed1987

Effect of different routes of immunization with bovine rotavirus on lactogenic antibody response in mice.

The effect of different routes of immunization with either live or killed bovine rotavirus (BRV) on the production of lactogenic antibody response in mice was evaluated. The routes of immunization were intramuscular (IM), oral (O) or intradermal in the mammary region (IMam). Following immunization, serum antibody responses were monitored by an enzyme linked immunosorbent assay (ELISA). Following whelping, the mice were allowed to stay with their mother until sacrificed on alternate days post-parturition from day 1-11. Milk from their stomach was collected for antibody titration by ELISA and virus neutralization test. Regardless of the routes of immunization, a rapid increase in serum anti-rotavirus antibody titers was observed for the first 5 wk after immunization followed by a gradual decline. After parturition, the mean antibody titer of lacteal secretions, as determined by ELISA, increased gradually for 7 days with the greatest increase on day 9, followed by a decrease in anti-rotavirus antibody. These titers also correlated with antibody titers in milk as measured by virus neutralization test. The best lactogenic antibody response was observed when IMam X IM X 2 route of immunization was used with live BRV as the antigen. Interestingly, immunization via the oral route with killed BRV also resulted in good antibody responses. In contrast, in the group where killed BRV was used, animals receiving 3X orally had the highest antibody titer. The distribution of different antibody subtypes in milk samples revealed IgG to be the predominant antibody followed by IgM and IgA. Irrespective of the route of administration, there was an increase in IgA on day 9 as compared to day 1 in most of the groups. The significant role played by mucosal immunity in passive protection and the possible ways to modulate subtype specific lactogenic immune response are discussed.

Administration, Oral↗
PubMed1994

Prevalence of antibody to hepatitis C virus (HCV) in HIV-1-infected patients (nice SEROCO cohort).

The prevalence of antibody to hepatitis C virus (HCV) in a cohort of 272 HIV-infected patients was assessed by means of 4 anti-HCV assays: a 1st generation and a neutralization test, a 2nd generation test, and a confirmatory test, the dot-blot Matrix HCV immunoassay. The cohort included, as a single risk factor, 35.7% intravenous drug users (IVDUs), 25% homosexual men, 30.1% heterosexual individuals, 5.9% transfused patients, 0.7% occupational infections, and 2.6% patients with unknown infection source, and was studied on entry and in samples collected for up to 36 months. Results showed that on entry (i) sera of 83 out of 272 members of the cohort were positive by the HCV 1st generation EIA (30.5%); 70 were confirmed by the neutralization test (84.3%); (ii) 115 of the cohort were reactive with the 2nd generation HCV EIA (41.3%); (iii) with the dot-blot immunoassay 99 (86.1%) of the cohort were confirmed and 16 remained indeterminate. The overall confirmed HCV antibody-positive rate in these 272 patients was 36.4%. Antibody to HCV was detected in 78.3% of IVDUs, 18.3% of heterosexual individuals, 31.2% of transfused patients, and only 2.9% of homosexual men. The 36-month follow-up of this cohort revealed that 4/145 patients became anti-HCV positive by second generation assay. Hepatitis B markers were frequently associated with HCV in IVDUs (71.1%) but infrequently in heterosexual (8.5%) or homosexual (1.5%) individuals. Our results suggest that HCV 2nd generation EIA used in combination with the semiautomated dot-blot assay as a confirmatory test improves the specificity and sensitivity for HCV antibody detection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

[Cultivation of the transmissible gastroenteritis virus in a continuous cell line].

Cell cultures of the permanent cell line SPEV to which the transmissive gastroenteritis virus had already been adapted were used to culture the virus and carry out the virus-neutralization test. Use was made of a cell suspension of a variable density--300 and 500 thou cells per cm3. Both variants of the cell suspension were comparatively studied in terms of growth, the production of a monolayer, susceptibility to infection, and titer of the virus obtained, using 4 test tubes with the virus at various rates of dilution which were kept under observation daily, keeping a record of the infected and noninfected cell cultures. The amount of the virus was determined by titration. It was found that the monolayer was produced more rapidly in the suspension containing 500 thou cells/cm3. In that case infection could be performed at the 24th hour. The cytopathic effect was more pronounced, and the titer of the virus obtained was higher. Successful attempts were made with the virus-neutralization test with the infection of the cell cultures in suspension. Thus, the entire procedure was shown to be labour-saving as the time for investigation of the sera was shortened.

Animals↗
PubMed1978

Variations in biological properties of geographic strains of western equine encephalomyelitis virus before and after passage in Culex tarsalis and Culiseta melanura.

Western equine encephalomyelitis (WEE) virus strains from the eastern and western United States were compared using two biological markers: antigenic properties measured by cross complement fixation (CF) tests and the size of plaques produced in Vero cell cultures. Slight antigenic differences were discernible on a geographic basis, and all of the virus strains from the West produced significantly larger plaques than the eastern isolates. One virus strain from each region was serially passaged in Culex tarsalis and Culiseta melanura by intrathoracic inoculation. No change in plaque size was detected as a result of mosquito passage. After passage of the eastern strain of WEE virus in C. tarsalis, its mouse brain CF antigen titer was increased to resemble the high CF antigen titer produced by the western strain. However, the antisera titers did not change when tested with this antigen. A cross plaque reduction neutralization test (PRNT) with the two virus strains before and after passage in mosquitoes failed to reveal any antigenic changes.

Animals↗
PubMed1993

Detection, typing, and subtyping of enteric adenoviruses 40 and 41 from fecal samples and observation of changing incidences of infections with these types and subtypes.

Monoclonal antibody (MAb) preparations specific for the enteric adenoviruses of subgenus F (AdF) were generated and evaluated as typing reagents in virus neutralization tests and enzyme-linked immunosorbent assays (ELISAs). A panel of 11 genome types of adenovirus 40 (Ad40), 24 genome types of Ad41, and 47 adenovirus prototype strains was used to determine the specificities of the MAbs in the two assays. In this way two MAbs, MAb 40-1 (anti-Ad40) and MAb 41-1 (anti-Ad41) were selected. These two MAbs showed strict type specificity in both assays. A third MAb reacted in an ELISA with all 47 human adenovirus types. With two other MAbs, three antigenic subtypes of Ad41 could be distinguished by their reactivities in virus neutralization tests and ELISAs. On the basis of the five selected MAbs, a sensitive ELISA system was developed for the direct detection and simultaneous typing and subtyping of Ad40 and Ad41 present in stool specimens. The five MAbs were also used to study the epidemiology of infections with Ad40 and Ad41 in The Netherlands in the period 1981 through 1989. It was shown that there were no significant fluctuations in the annual incidence of the cluster of enteric adenoviruses as a whole. This cluster should therefore be considered to belong to the "endemic" rather than the "epidemic" adenoviruses. The relative incidence of Ad40 infections compared with that of Ad41 infections changed considerably during the period studied; the proportion of Ad41 infections rose from about 30% in 1981 to about 95% in 1986, after which it stabilized at 90 to 95%. The proportion of one of the subtypes of Ad41 (Ad41 subtype M3) increased from about 40 to 80% in the same period.

Adenovirus Infections, Human↗
PubMed1993

Presumptive identification of common adenovirus serotypes by the development of differential cytopathic effects in the human lung carcinoma (A549) cell culture.

The neutralization test is commonly used in clinical virology laboratories for the identification by serotype of adenovirus isolates. In an effort to conserve reagents and reduce the amount of time in the performance of this assay, we evaluated the significance of differential cytopathic effects for the presumptive identification of lower-numbered adenovirus serotypes that are commonly encountered in the clinical setting. Utilizing the human lung carcinoma (A549) cell culture as our indicator system, two viral induced monolayer degenerations (i.e., cytopathic effects or CPEs) were recognized. Among our wild and the laboratory adapted (i.e., ATCC) adenovirus isolates tested in this study, serotypes 1, 2, 4, 5, 6, 8, 11, 19, 21, 27, and 31 were expectedly characterized by the typically enlarged, rounded, and refractile cells, which eventually aggregated into irregular 'grape-like' clusters. Adenovirus types 3 and 7, however, were characterized by the development of distinct intranuclear inclusions, a flattening and then a web or net-like monolayer degeneration. Differences in the intensity of intranuclear granulation were related by electron microscopy to differences in the quantity of viral crystalline aggregates within the host cell nucleus. A presumptive identification of the commonly encountered adenovirus serotypes 3 and 7 prior to the performance of the neutralization test would result in a conservation of type-specific antiserum, a decreased use of cell cultures and medium, and lastly, reduced medical technologist workload.

Adenoviruses, Human↗
PubMed1999

Acute follicular conjunctivitis caused by adenovirus type 34.

PURPOSE: Adenovirus type 34 belongs to adenovirus subgenus B. The prototype virus of adenovirus 34 was isolated from a renal transplant recipient. However, no case of acute conjunctivitis caused by adenovirus 34 has been reported. Recently, we encountered two cases of acute follicular conjunctivitis in which adenovirus 34 was isolated. METHODS: The clinical isolates were identified by the standard neutralization test. The sequences of seven hypervariable regions in the hexon protein of these cases were compared with those of several prototype strains of adenovirus subgenus B. RESULTS: The cases were middle-aged, 34 and 41 years old, and male, and they exhibited moderate conjunctivitis with upper respiratory tract symptoms. Isolates from cell culture were identified as adenovirus 34 by NT. The mean homology rate (percentage of total number of coincident amino acids in the total length of amino acids in seven hypervariable regions) between clinical isolates and the adenovirus 34 prototype was 96.5%; in contrast, those between clinical isolates and the prototypes of adenovirus 11, adenovirus 14, and adenovirus 35 were 55.6%, 66.7%, and 57.9%, respectively. The results of conventional serotyping by neutralization test were confirmed by these values. CONCLUSIONS: These results indicate that adenovirus 34 may induce acute conjunctivitis in immunocompetent subjects and that special attention should be paid to adenovirus 34 as a causative agent for adenoviral conjunctivitis.

Acute Disease↗
PubMed1985

Problems in the interpretation of diagnostic tests due to cross-reactions between orbiviruses and broad serological responses in animals.

Tests presently used for the diagnosis of infections by bluetongue virus (BTV) or related orbiviruses are based on the use of 2 types of serological reactions. Those that are considered group-reactive tests are the agar gel diffusion precipitin (AGDP), complement-fixation (CF) and fluorescent antibody tests and those that are considered type-specific are a wide variety of virus neutralization tests (50% and 80% plaque reduction, plaque inhibition and microtiter neutralization) and cross-protection tests. These tests suffer from problems of standardization between laboratories and of specificity. Group-reactive tests (AGDP and CF) for the BTV serogroup also detect cross-reactions with viruses in the epizootic hemorrhagic disease virus (EHDV), Eubenangee (EUB) and Palyam (PAL) serogroups, with the EHDV cross-reactions being of particular concern. Further, multiple infections of cattle with PAL serogroup members can produce antibodies which will react to BTV and EHDV serogroup antigens in serological tests. Multiple infections of animals with related viruses can produce antibodies which will cross-react with orbiviruses in type-specific, virus neutralization tests to a virus which the animal has not previously been exposed. These observations stress the need to evaluate the tests at present being used, to assess the risks of cross-reactions between related orbiviruses and to develop new tests of defined specificity.

Animals↗
PubMed2004

Clinical signs and results of specific diagnostic testing among captive birds housed at zoological institutions and infected with West Nile virus.

During 2002, West Nile virus (WNV) infection was diagnosed in 11 birds housed in outdoor exhibits at 5 zoological institutions in Kansas. Eight birds were examined because of neurologic abnormalities; 2 died suddenly without any clinical signs of disease. Results of CBCs and serum biochemical testing were nonspecific. Results of a plaque reduction neutralization test to detect circulating antibodies against WNV were positive for 2 of 8 birds. Results of a reverse transcriptase-polymerase chain reaction assay of an oral cavity swab specimen for WNV RNA were positive for 4 of 5 birds. One bird survived; the remaining 10 died or were euthanatized, with 9 of the 10 dying or being euthanatized within 3 days of the onset of clinical signs. In all 10 birds that died or were euthanatized, WNV infection was confirmed on postmortem examination by means of specific testing. Findings in these birds suggest that West Nile virus infection can be difficult to diagnose antemortem because clinical signs mimic those associated with other more common avian diseases. Neither of the antemortem diagnostic tests was definitive for diagnosing WNV infection in these cases.

Animals↗
PubMed1977

New human adenovirus (candidate adenovirus type 35) causing fatal disseminated infection in a renal transplant recipient.

An antigenically distinct adenovirus is described which was isolated in March 1973 from the lungs and kidney of a 61-year-old woman who died of diffuse interstitial adenovirus pneumonia 55 days after receiving a cadaveric renal allograft. Complement fixation, hemagglutination inhibition, and serum neutralization tests on sequential serum specimens from the patient confirmed that the adenovirus infection occurred in coincidence with her clinical illness and failed to document concomitant infection by any other common respiratory agent. Pathological and virological findings indicated that the pneumonia was only one manifestation of a disseminated adenovirus infection, the source of which may have been a latent infection pre-existing in the donor kidney. The adenovirus, purified by terminal dilution and plaque procedures, has antigenic, morphological, biological, biophysical, host susceptibility, and hemagglutinating properties characteristic of adenovirus group 1A. Buoyant densities in CsCl are 1.340 g/ml for the virion, 1,300 g/ml for the group complement-fixing (hexon) antigen, and 1.290 g/ml for the major soluble complete hemagglutinin (dodecon). The virus was serologically distinct from adenoviruses 1 to 34 in reciprocal serum neutralization tests with antisera to these viruses. We propose this virus as candidate adenovirus type 35 (holden).

Adenoviridae Infections↗