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 1,099 records · Page 61Linked to original sources
PubMed1967

Virus aggregation as the cause of the non-neutralizable persistent fraction.

The non-neutralizable or persistent fraction of virus populations has been found to be caused by aggregated virus. Detailed investigation was performed with the prototype strain of echovirus type 4 (Pesascek), as this virus is notorious for its large non-neutralizable fraction. When Pesascek virus was clarified by low-speed centrifugation, homologous antiserum hardly neutralized the virus. However, when the virus was filtered through membranes having a porosity only twice the diameter of the virus, monodispersed virus was obtained which was efficiently neutralized. Serum titers were up to 1,000 times higher if the neutralization test was carried out with monodispersed virus. Virus in non-neutralizable aggregates was found to constitute 30% of the infective units of unfiltered Pesascek virus but only 0.1% of the antigenically related DuToit strain. This explains why DuToit strain has been a more satisfactory indicator strain for detecting type 4 antibodies, regardless of the echo 4 strain used for inducing the antibodies. Clarified suspensions and ultrafiltrates of viruses belonging to the picorna-, reo-, myxo-, adeno-, herpes-, and poxvirus groups were studied. Clarified suspensions yielded persistent fractions of 0.005% for poliovirus, of 0.1% for reovirus, of 0.6% for influenza virus, of <0.001% for adenovirus, of 0.06% for herpesvirus, and of 10 to 30% for vaccinia virus. In all cases the persistent fractions were removed by membrane filters which had a pore diameter no larger than twice that of the virus under test, and the high concentration of virus in each ultrafiltrate was completely neutralized by antiserum.

Adenoviridae↗
PubMed1998

Reactivities of feline calicivirus field isolates with monoclonal antibodies detected by enzyme-linked immunosorbent assay.

Reactivities of feline calicivirus (FCV) field isolates with monoclonal antibodies (MAbs) were examined by enzyme-linked immunosorbent assay (ELISA). The reactivities of the viruses in ELISA were different from our previous results using the neutralization tests (NT). Many isolates were positive in ELISA with MAbs which recognized neutralizing epitope 3B and/or 4. However, most were negative in NT in our previous study. After absorption of two FCV strains with host cells, the non-infectious virus fluid still reacted with MAb, which recognized epitope 3B and/or 4 in ELISA. These results indicated the possibility that neutralizing epitopes are expressed on non-infectious virus particles or exist as proteinaceous molecules in virus fluid.

Animals↗
PubMed2005

Persistent infection of betanodavirus in a novel cell line derived from the brain tissue of barramundi Lates calcarifer.

In order to obtain an in vitro system for studying the mechanism of persistent infection of fish nodavirus, a novel cell line (BB) was established from the brain tissue of a barramundi, Lates calcarifer, which had survived viral nervous necrosis disease. The cell line has been subcultured > 100 times. The persistence of fish nodavirus designated as barramundi brain nervous necrosis virus (BBNNV) in the BB cells was demonstrated by: (1) the detection of the infectious virus in the culture supernatants, (2) the detection of NNV nucleic acids extracted from the BB cells, (3) the positive result of immunochemical staining using an NNV-specific monoclonal antibody and (4) their resistance to infection by another fish nodavirus grouper NNV (GNNV). No temperature-sensitive mutants were detected in the culture supernatant of the BB cells. Neither truncated genome (RNA1 or RNA2) nor smaller coat protein was found in the purified BBNNV particles, suggesting that defective interfering particles were unlikely to be important in the NNV-persistent infection in the BB cells. The result of the neutralization test indicated that the 5 antigenic determinants, recognized by GNNV-specific neutralizing antibodies, also existed on the coat protein of BBNNV. The BB cell line is the first cell line reported to be persistently infected with NNV, and would be a useful model for understanding the mechanisms of NNV-persistent infection in vitro and in vivo.

Animals↗
PubMed1982

Antigenic relationships of flaviviruses with undetermined arthropod-borne status.

In contrast to most of the arthropod-borne flaviviruses, the flaviviruses with undetermined arthropod-borne status are probably disseminated only by direct contact with excreta (saliva, urine, feces, etc.); however, as yet undescribed arthropod transmission cycles may be found for some of them. Twenty-two of these flaviviruses, including prototype and recently isolated strains, were compared. Biologic properties were defined by infectivity titrations in suckling mice and Vero, LLC-MK2, and primary Pekin duck embryo cells, and antigenic relationships were defined by complement-fixation and plaque reduction neutralization tests. An antigenic classification scheme is proposed. Antigenic and biologic properties delimit two large clusters. The first, comprising a single antigenic complex, includes those which have yet to be isolated from arthropods, but are likely to be so (Israel turkey meningoencephalitis, Koutango, Negishi and Aroa viruses). The second, encompassing five antigenic complexes, is comprised of viruses which have been isolated exclusively from rodents or bats (Saboya, Carey Island, Dakar bat, Sokuluk, Bukalasa bat, Entebbe bat, Phnom Penh bat, Modoc, Sal Vieja, Jutiapa, San Perlita, Cowbone Ridge, Rio Bravo, Apoi, Tamana bat and Montana Myotis leucoencephalitis viruses) but includes three viruses (Saboya, Sokuluk and Entebbe bat viruses) which may be arthropod-borne, as indicated by replication in mosquito cells in vitro.

Aedes↗
PubMed1985

Serotypes of bluetongue virus present in Saudi Arabia.

The widespread occurrence of infection with bluetongue virus (BTV) in Saudi Arabia has been demonstrated by immunodiffusion testing. Subsequently, 31 sheep sera and 1 goat serum with clear precipitating activity were examined by neutralization test using the 22 reference serotypes of BTV. Only 12 sheep sera neutralized 1 or more of BTV serotypes: 6 (1 serum), 14 (2 sera), 17 (4 sera), 19 (1 serum) and 20 (11 sera). The goat serum neutralized only serotype 19 of BTV. On the other hand, 19 sheep sera failed to neutralize any known BTV serotype. The significance of these serological findings was discussed and planning for further studies to isolate local BTV strains from sentinel flocks of lambs and calves was proposed.

Animals↗
PubMed1995

Salmonid herpesvirus 2. Epizootiology and serological relationship.

Herpesvirus infections of kokanee salmon, masu salmon, coho salmon, and rainbow trout have been reported in Japan. The 11 herpesvirus strains isolated from kokanee salmon (NeVTA), masu salmon (YTV and 3 strains of OMV), coho salmon (CSTV, COTV and 2 strains of OKV), rainbow trout (RKV and RHV), and Herpesvirus salmonis were compared for their serological relatedness by serum cross-neutralization tests with polyclonal rabbit antiserum. The herpesvirus strains isolated in Japan were neutralized by antisera against these viruses and were found to be closely related to salmonid herpesvirus 2 (OMV strain 00-7812). These strains were, however, clearly distinguished from salmonid herpesvirus 1 (H salmonis).

Animals↗
PubMed1995

[A comparison of the results obtained in IgM serology and anti-Coxsackie A9 (strain 47) neutralization in cases of epidemic neuropathy and their contacts].

A number of 213 monosera from patients presenting with epidemic neuropathy and their contacts was studied by indirect immunofluorescence and neutralization tests with the aim of demonstrating the presence of serum IgM and neutralizing antibodies against the strain 47/93 IPK identified as a Coxsackie A9 virus. The mean age of the patients ranged from 20 to 59 years and positivity to both techniques was not found to be predominant for one or another sex. No significant difference was observed with respect to results obtained between patients and contacts with the techniques used for the study.

Adult↗
PubMed2007

Detection of antibodies to Japanese encephalitis virus in the wild boars in Hiroshima prefecture, Japan.

Serum specimens were collected from 25 wild boars in Hiroshima prefecture located in the western region of Japan from November 2004 to February 2005. The sera were tested for antibodies to Japanese encephalitis virus (JEV) by IgM capture and IgG enzyme-linked immunosorbent assays (ELISA), and plaque reduction neutralization test. Seventeen samples (68%) were positive for neutralizing antibody to JEV. All the neutralizing antibody-positive samples were positive for IgG-ELISA. One was also positive for IgM. The results indicate that approximately 70% of the wild boars were positive for anti-JEV antibody, and raises the possibility that wild boars may play a role in the infectious cycle of JEV in this region.

Animals↗
PubMed1984

Enzyme-linked immunosorbent assay for detection of transmissible gastroenteritis virus antibody in swine sera.

An enzyme-linked immunosorbent assay (ELISA) was developed for detection and quantification of serum antibodies to transmissible gastroenteritis virus (TGEV) in swine. Sera from pigs inoculated with cell culture-origin TGEV or gut-origin TGEV were tested for anti-TGEV antibody by ELISA and by serum virus-neutralization test (NT). The ELISA detected antibody 3 days (av) sooner than did the NT when sera from pigs inoculated with cell culture-origin TGEV were tested and 1 day sooner than did the NT when sera from pigs inoculated with gut-origin TGEV were tested. The ELISA appeared to be more sensitive than the NT, since ELISA was more responsive to low-level antibody and ELISA titers exceeded NT titers.

Animals↗
PubMed2004

Tetanus antibody assay combining in-house ELISA and particle agglutination test and its serosurvey application in a province in Turkey.

In order to determine a practically useful quantitative assay method for tetanus antibody in a large-scale seroepidemiological study, a method combining an in-house ELISA with a particle agglutination test (KPA) was evaluated in comparison with the in vivo mouse neutralization test. Serum samples with mouse neutralization antibody titers 0.01 IU/ml (the minimum protective level) or below showed considerable overestimation of antitoxin titers up to 1.0 IU/ml when studied by in-house ELISA alone. On the other hand, the KPA values were highly correlated with the mouse test, even in cases of titers equal to 0.01 IU/ml or below. The combination of these two procedures, in which in-house ELISA values of 1.0 IU/ml or below were replaced by KPA values, provided a high correlation in antibody titers with the mouse test (r = 0.968). We applied this combined method to a tetanus seroepidemiological survey in a province in Turkey. The survey included 347 subjects from the healthy population, and the quantitative analyses showed high antibody levels in children and young adults and significantly low levels among adults aged 40 or over. A characteristic distribution of antibody titers in each age group was also demonstrated.

Adolescent↗
PubMed1991

Seroprevalence of antibodies against encephalomyocarditis virus in swine of Iowa.

A total of 2,614 swine from 104 herds located throughout Iowa were tested for antibodies against encephalomyocarditis virus (EMCV) by use of the microtitration serum neutralization test. The sample was composed of 587 sows and gilts and 2,027 finishing swine. A statistically significant (P less than 0.002) difference was observed between prevalence in sows and gilts (17.2%) and that in finishing swine (12.2%). Breeding swine maintained in total confinement (20.5%) had significantly (P = 0.04) higher prevalence than did breeders maintained in other types of housing (12.1%), whereas prevalence in finishing swine raised in total confinement (6.4%) was significantly (P = 0.02) lower that in finishers not raised in total confinement (13.6%). Association was not detected between prevalence and herd size or between prevalence and season of the year. Adjusting for test specificity and sensitivity, the true prevalence of EMCV infection in swine in Iowa was estimated to be 13.8% in breeding stock and 8.5% in finishing swine. On a herd basis, 89.4% (93/104) of the herds had one or more EMCV-positive swine.

Animals↗
PubMed2005

Development of a tissue-culture-based enzyme-immunoassay method for the quantitation of anti-vaccinia-neutralizing antibodies in human sera.

Vaccination with vaccinia virus is carried out in order to induce protection against variola virus, the causative agent of smallpox. Serum titer of vaccinia virus-neutralizing antibodies is considered to be well-correlated with in vivo protection. Plaque reduction neutralization test (PRNT) is the gold standard for detecting and quantifying vaccinia virus-neutralizing antibodies in sera of vaccinees. However, PRNT is time and labor consuming, which does not allow large-scale screening needed for a population survey. A simplified, sensitive, standardized, reproducible and rapid method, neutralization tissue-culture enzyme immunoassay (NTC-EIA) was developed for quantitation of neutralizing antibodies against vaccinia virus. The assay consists of the following steps: neutralization of the virus with serially diluted sera, infection of cells in culture and measurement of residual virus replication using an enzyme immunoassay. The assay can be used for animal (rabbit) or human sera. Titer averages obtained using NTC-EIA were highly correlated (R2=0.9994) to those obtained using PRNT. The assay is carried out in 96-well plates and takes only 2 days to complete. With the appropriate setup, it can be automated fully to allow screening of a large number of sera.

Antibodies, Viral↗
PubMed1996

Isolation of reovirus type 2 from diarrheal feces of pigs.

Reoviruses designated as OS-320 to OS-324 were isolated from a total of 5 fecal specimens from 3 with diarrhea and 2 apparently healthy pigs aged 3 months. The serotype of these isolates was determined as reovirus type 2 by cross neutralizing tests. Furthermore, the results of hemagglutination test suggested the isolates were different from the other reoviruses. A survey of neutralizing antibody against reoviruses showed type 2 virus was widely prevalent among pigs in Okayama Prefecture. This paper is the first report of the isolation of reovirus type 2 from pigs.

Animals↗
PubMed1989

Prevalence of rabies specific antibodies in the Mexican free-tailed bat (Tadarida brasiliensis mexicana) at Lava Cave, New Mexico.

Adult female and juvenile Mexican free-tailed bats (Tadarida brasiliensis mexicana) were collected bimonthly at Lava Cave, New Mexico from May through September. The purpose of this study was to examine the prevalence of active rabies infection as well as to determine individual immune status in these hosts. All bats were bled and examined for rabies antibody (total antibody versus IgM) utilizing a modified serum neutralization test. The brains were removed and examined by the fluorescent rabies antibody (FRA) test. No significant difference was observed in the number of adults with rabies neutralizing antibody (total) over the study period. Significant differences in rabies neutralizing antibody (total) were observed among the juveniles sampled during July and August. The number of adults with IgM specific antibody was low (15 of 750, 2%) and did not fluctuate significantly. However, the number of juveniles with IgM antibody did show increased levels in August and September. The number of adults positive by the FRA was low (4 of 750, less than 1%) and did not appear to fluctuate significantly over the study period. The number of juveniles positive by the FRA was three and one-half times higher than observed for the adults (14 of 600, 2%). These results indicate that the Mexican free-tailed bat appears to be exposed to rabies virus shortly after birth as evident by its immune status. The low prevalence (4 of 750, less than 1%) of active infection as determined by the FRA and mouse inoculation and the high prevalence (514 of 750, 69%) of IgG antibody in the adult females indicate that the Mexican free-tailed bat recovers from rabies virus infection.

Animals↗
PubMedDate not supplied

[Composition and immunochemical properties of goat immunoglobulins against the Ebola virus].

Serum samples containing Ebola Virus neutralizing antibodies were prepared by prolonged immunization of goats with 10% liver homogenate from guinea pigs infected with Ebola virus. Differences in IgG fractions of normal and hyperimmune caprine blood sera were detected. Analytical chromatography on Polysil SA and immunodiffusion showed the presence of three IgG-containing fractions in hyperimmune sera. Immunochemical properties of these fractions were studied by solid-phase enzyme immunoassay and neutralization test. Antibodies to viral antigens were referred to IgG2 and IgG1a, and virus neutralizing properties were found mainly in IgG2 antibodies. Immunoglobulins were isolated from hyperimmune serum by alcohol sedimentation. The principal IgG fraction was found to contain much lower levels of antibodies to guinea pig liver antigens than intact serum, but at the same time it was characterized by a higher neutralization index.

Animals↗
PubMed1985

[A basic study on the anti-tumor activity of peripheral lymphocytes of tumor-bearing rats by in vitro culture].

In order to establish passive cancer immunotherapy by in vitro culture of lymphocytes, several methods were devised to induce and augment anti-tumor activity of peripheral blood lymphocytes (PBL) in the presence of interleukin-2 (IL-2). In vitro experiment: Weak anti-tumor activity appeared on culture of PBL in the presence of IL-2. On addition of MMC treated tumor antigen, the anti-tumor activity was augmented. Anti-tumor activity further increased on addition of peritoneal exudate macrophages or peripheral whole white blood cells containing monocytes to (2) as accessory cells. Effect similar to (3) was obtained in MLTC of peripheral whole white blood cells. [II] In Winn neutralization test, the strongest tumor-neutralizing activity was seen in the group of cultured lymphocytes with antigen and in the group of cultured leukocytes with antigen. This result agreed excellently with the results of the in vitro experiments [I]. [III] In the therapeutic experiment: Significantly better effect was noted in the treated group by cultured leukocytes with antigen than in the treated group by non-cultured lymphocytes. The treatment with 10(7) lymphocytes produced definitely prolonged survival of tumor-bearing rats compared to the treatment of 10(6) or less number lymphocytes.

Animals↗
PubMed1965

STUDIES ON TRANSMISSIBLE GASTROENTERITIS OF SWINE. I. THE ISOLATION AND IDENTIFICATION OF A CYTOPATHOGENIC VIRUS OF TRANSMISSIBLE GASTROENTERITIS IN PRIMARY SWINE KIDNEY CELL CULTURES.

Two virus isolates from transmissible gastroenteritis (TGE) of swine were adapted to grow in primary swine kidney cells. Growth of the virus was indicated by the resistance of the infected cells to the cytopathic effect of a virus diarrhea virus of cattle, and by the development of large round cells on the cell sheet. Evidence that these virus isolates were TGE was obtained by the development of signs of the disease followed by death of exposed SPF pigs, or the resistance of the recovered pigs to further signs of disease when they were exposed to virulent TGE contained in virus bearing intestinal tissue. The in vitro and in vivo serum neutralization tests, along with staining of infected cells by fluorescein conjugated TGE antiserum, gave further indication of the specific nature of the virus growing in the cell cultures.

Animals↗
PubMedDate not supplied

Coxsackie virus infections in rheumatic fever.

The close relationship between Group A beta Hemolytic Streptococci (GABS) and rheumatic fever is a well established one. However, the concept of the streptococcus as the sole etiologic agent of the rheumatic heart disease (RHD) has been challenged over the past years. Since coxsackievirus group B (CVB) has long been proposed as a cause of acquired valvular disease simulating rheumatic fever, we attempted in this study to document infections with this group of viruses in patients with rheumatic fever. We obtained blood samples from 106 patients with old (quiescent) rheumatic fever/rheumatic heart disease [group I], 94 patients with acute rheumatic fever (ARF) [group II], and 74 normal matched controls. We tested for the presence of neutralizing antibodies to the 6 serotypes of CVB by a micro neutralization test. We have found that infection with CVB, especially types B2 and B4, was common in the studied population. Forty-two percent of normal individuals had evidence of infection with any of the 6 serotypes of CVB. Patients of group I had significantly more frequent infections with CVB 2. Patients in group II had significantly more frequent infections with CVB 2 and CVB 6. There was no clear correlation between such infections and the clinical course of rheumatic fever. There was no difference in the incidence of CVB infections between patients with definite ARF, and patients with suspected ARF. We set a low order association between rheumatic fever and infection with CVB types B2 and B6. We emphasize the importance of pursuing the investigation of the role of CVB in relation to RHD.

Adolescent↗