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 811 records · Page 45Linked to original sources
PubMed1983

[Evaluation of the specificity of skin allergy tests in cattle with IBR-IPV].

An allergic and serologic investigation was carried out by the skin allergic test (SAT) and the virus neutralization test (VNT) to demonstrate the presence of infectious bovine rhinotracheitis -- infectious pustular vulvovaginitis (IBR-IPV) in cattle divided into three groups according to age, treated with the live attenuated vaccine MK25 against Aujeszky's disease. It was found that this vaccine induced the production of specific antibodies against the virus of IBR-IPV, which could be demonstrated through VNT (beta-variant) in low titers (2-2.5 log10), while through VNT (alfa-variant) no specific antibodies could be found. On the other hand, the virus of Aujeszky's disease did not usually lead or on very rare occasions (massive virus doses and continuous antigenic challenge) led to allergization of the body of cattle for IBR-IPV as well as to a positive SAT. Out of a total of 30 investigated calves only one proved positive by SAT, and 2 others were suspected of being carriers of infection. The problem is discussed of the specificity of SAT and its diagnostic value in IBR-IPV under some epizootiologic circumstances.

Age Factors↗
PubMed1999

Evaluation of immune responses to inactivated influenza vaccines prepared in embryonated chicken eggs and MDCK cells in a mouse model.

This study was initiated with the isolation of influenza A and B viruses from clinical throat swabs in both fertile chicken eggs (egg) and MDCK cells, which were used in subsequent vaccine production in the above two hosts. On the basis of haemagglutination-inhibiting (HI) tests, immune mouse sera from mice vaccinated with MDCK cell-derived vaccines revealed antigenic similarities among H3N2 or B viruses isolated in MDCK cells or eggs. Similarly, antiserum prepared by immunization with egg-derived H3N2 vaccine showed equivalent antigenicity between homologous and heterologous (MDCK cell-derived) viruses. In contrast, antigenicity of egg-derived B vaccines was differed somewhat from that of MDCK cell-derived vaccines, suggesting the occurrence of antigenic change due to passaging in eggs. The time-course of immune responses based on HI titres indicated that MDCK cell-derived vaccines elicited extremely high antibody levels. Also, it was evident that antibody production by MDCK cell-grown H3N2 vaccine was very similar to that of vaccine prepared from egg-grown viruses. These results were comparable to those of plaque neutralization tests, although antigenic differences between egg- and MDCK cell-derived challenge viruses were confirmed in the test with antiserum to MDCK cell-derived vaccine. Consistent with HI-antibody production, the immunogenicity of MDCK cell-derived B vaccine appeared to be low by plaque neutralization test, while immune responses in mice which received egg-derived vaccines were significantly higher than that of the former. Furthermore, immune responses confirmed in mice immunized with B virus vaccines prepared in eggs revealed slight antigenic differences between two viruses derived from their respective hosts. Nevertheless, through evaluation of immune responses, MDCK cell-derived influenza vaccines may be useful when weak immunogenicity of B virus vaccine is improved.

Animals↗
PubMed1991

Analysis of the neutralization epitopes on human rotavirus VP7 recognized by monotype-specific monoclonal antibodies.

Three anti-VP7 monoclonal antibodies (MAbs) which neutralized only two strains (K8 and S12) of five serotype 1 human rotaviruses (HRVs) were obtained, and neutralization epitopes recognized by these 'monotype-specific' MAbs were analysed by epitope mapping and sequencing of the VP7 genes. Neutralization-resistant mutants of K8 and S12 were selected by the monotype-specific MAbs and serotype 1-specific MAbs prepared previously. Cross-neutralization tests between MAbs and neutralization-resistant mutants of K8 and S12 indicated that epitopes of monotype-specific MAbs operationally overlap with those of serotype 1-specific and cross-reactive MAbs recognizing the S1 region. Sequence analyses of the VP7 genes indicated that VP7s of strains K8 and S12, which belong to a monotype of serotype 1 viruses, possessed amino acids at positions 42 and 87 different from other serotype 1 HRVs. Furthermore, amino acid substitution sites of representative mutants of K8, selected by the monotype-specific MAbs, were identified at positions 96, 97 and 100. These results imply that amino acids in variable region B (amino acids 87 to 101) are involved in the monotype-specific neutralization epitope as well as serotype-specific neutralization epitopes.

Amino Acid Sequence↗
PubMed1989

Morbillivirus infection of seals (Phoca vitulina) during the 1988 epidemic in the Bay of Heligoland. I. Mode, frequency and significance of cultural virus isolation and neutralizing antibody detection.

From 16 (14%) out of 112 dead or euthanized seals originating from wildlife and seal orphanages phocine morbillivirus was isolated. The majority of viral isolates in cell cultures was obtained from lung homogenates of 15 out of 71 free-ranging seals (21%). The virus was isolated by longterm cultivation in roller cultures of seal kidney cells. The phocine morbillivirus was detected by typical cytopathogenic alteration and by peroxidase-linked antibody (PLA) assay, respectively. A neutralization test based on PLA was used for antibody detection in seals using a canine distemper virus (CDV) strain and in parallel one of the phocine morbillivirus isolates. All sera tested were proven to contain neutralizing antibodies of higher titres against the latter virus than against the CDV strain. Several seals furnished morbillivirus isolates and at the same time exhibited neutralizing antibodies of low to medium titres. No viral isolates were obtained from the majority of sick animals with moderate to high neutralizing titres (greater than 1/1,000). The significance of these findings is discussed in relation to the cause of the mass mortality amongst seals observed in 1988 in the Bay of Heligoland.

Animals↗
PubMed2004

Identification of chimpanzee Fab fragments by repertoire cloning and production of a full-length humanized immunoglobulin G1 antibody that is highly efficient for neutralization of dengue type 4 virus.

A safe and effective dengue vaccine is still not available. Passive immunization with monoclonal antibodies from humans or nonhuman primates represents an attractive alternative for the prevention of dengue virus infection. Fab monoclonal antibodies to dengue type 4 virus (DENV-4) were recovered by repertoire cloning of bone marrow mRNAs from an immune chimpanzee and analyzed for antigen binding specificity, V(H) and V(L) sequences, and neutralizing activity against DENV-4 in vitro. Fabs 5A7, 3C1, 3E4, and 7G4 were isolated from a library constructed from a chimpanzee following intrahepatic transfection with infectious DENV-4 RNA. Fabs 5H2 and 5D9, which had nearly identical V(H) sequences but varied in their V(L) sequences, were recovered from a library constructed from the same chimpanzee after superinfection with a mixture of DENV-1, DENV-2, and DENV-3. In radioimmunoprecipitation, Fab 5A7 precipitated only DENV-4 prM, and Fabs 3E4, 7G4, 5D9, and 5H2 precipitated DENV-4 E but little or no prM. Fab 3E4 and Fab 7G4 competed with each other for binding to DENV-4 in an enzyme-linked immunosorbent assay, as did Fab 3C1 and Fab 5A7. Fab 5H2 recognized an epitope on DENV-4 that was separate from the epitope(s) recognized by other Fabs. Both Fab 5H2 and Fab 5D9 neutralized DENV-4 efficiently with a titer of 0.24 to 0.58 micro g/ml by plaque reduction neutralization test (PRNT), whereas DENV-4-neutralizing activity of other Fabs was low or not detected. Fab 5H2 was converted to full-length immunoglobulin G1 (IgG1) by combining it with human sequences. The humanized chimpanzee antibody IgG1 5H2 produced in CHO cells neutralized DENV-4 strains from different geographical origins at a similar 50% plaque reduction (PRNT(50)) titer of 0.03 to 0.05 micro g/ml. The DENV-4 binding affinities were 0.42 nM for Fab 5H2 and 0.24 nM for full-length IgG1 5H2. Monoclonal antibody IgG1 5H2 may prove valuable for passive immunoprophylaxis against dengue virus in humans.

Amino Acid Sequence↗
PubMed1986

[Studies on new adenovirus types of subgenus D causing conjunctivitis--antigenic and restriction endonuclease analysis of adenovirus types 19 and 37].

Neutralization test and DNA restriction endonuclease analysis were performed in strains of adenovirus types 19 (Ad-19) and 37 (Ad-37) isolated from patients with acute conjunctivitis in Sapporo, Kao-Hsiung (Taiwan) and Pusan (Korea) in the period of 1979 and 1984. Although Ad-19 and Ad-37 were differentiated, they were related to each other in neutralization test. There was no difference between prototype strain and isolates in Ad-19 and Ad-37 strains. By DNA restriction endonuclease analysis Ad-19 isolates were clearly distinct from Ad-19 prototype strain (AV-587) and Ad-37 strains. And it was suggested that these Ad-19 isolates from East Asia were as same as isolates from Europe named Ad-19a. Ad-37 isolated strains were as same as Ad-37 prototype strain (GW) by SmaI, SacI, SalI, BamHI, EcoRI, XhoI, HindIII restriction analysis. But some strains were distinct from prototype strain by only HindIII restriction analysis, and they were new subtype of Ad-37 which had never been reported.

Adenoviridae Infections↗
PubMed1978

Radioimmunoassay for quantitation of antibodies to alphaviruses with staphylococcal protein A.

A radioimmunoassay (RIA) procedure is described for measuring antibodies to alphaviruses in human and other mammalian sera. The test employed protein Abearing Staphylococcus aureus as a solid-phase immunoadsorbent for (3)H-labeled viruses complexed with immunoglobulin G. Using antibodies produced in humans and guinea pigs, the RIA procedure clearly differentiated among antibodies to Venezuelan, western, and eastern equine encephalomyelitis viruses. Sensitivity of the RIA depended on the concentrations of labeled viruses employed. The dilution of serum that effected binding of 50% of the (3)H-labeled virus (determined by probit analysis) was consistently higher than the neutralizing antibody titer determined by a conventional plaque reduction neutralization test using 80% plaque reduction end points. In addition, sera from 73 individuals were screened for seroconversion following live attenuated Venezuelan equine encephalomyelitis virus vaccine (strain TC-83) inoculation, by RIA using a single serum dilution (1:80); results were identical with seroconversions identified by plaque reduction neutralization test. Hyperimmune Venezuelan equine encephalomyelitis virus sera from a number of mammalian species were successfully titrated by RIA; the species tested were human, guinea pig, white rat, rabbit, burro, dog, monkey, sheep, and cotton rat. The protein A-mediated RIA is a rapid, sensitive, specific, and precise serological tool for measuring antibodies to surface antigens of alphaviruses, and should allow the subsequent development of a competitive binding RIA to measure antigenic potency of inactivated alphavirus vaccines.

Animals↗
PubMedDate not supplied

Prevalence of Arkansas-type infectious bronchitis virus in Delmarva peninsula chickens.

The prevalence of Arkansas (Ark)-type infectious bronchitis virus (IBV) in Delmarva peninsula broiler-type chickens was determined. The immunity of 5-to-11-week-old commercial broilers was evaluated by intraocular inoculation with Ark-type DPI strain (Ark DPI) challenge virus and collection of tracheal swabbings 5 days later. Serum Ark-type antibody titers were obtained using the virus-neutralization test. Eighty-five flocks were tested from January to August 1981. Nearly 60% of the flocks had substantial (greater than or equal to 70%) local immunity of the upper respiratory tract. Twenty-two percent had intermediate (50-69%) and 19% of the flocks had low (less than or equal to 40%) levels of local immunity. Serum antibody titers generally agreed with challenge results. In addition, high Ark-type IBV neutralizing-antibody titers were found in 16 Delmarva broiler breeder flocks. Seven current IBV field isolates were characterized for antigenic similarity to Ark DPI. Four isolates contained Ark antigen(s) based on significant neutralization in virus-neutralization tests and on substantial immunity to challenge afforded by Ark DPI virus immunization. Three isolates did not appear to contain Ark antigen(s). Immunization of chickens with Ark DPI virus afforded substantial protection against Connecticut- and homologous-type virus challenge, partial immunity (63%) against JMK, and no protection against the Massachusetts 41 strain of IBV.

Animals↗
PubMed1958

Antigenic variants of influenza A virus (PR8 strain). IV. Serological characteristics of a second line of variants developed in mice given polyvalent vaccine.

A second series of four variants of PR8-S virus has been produced by passage of the variants in the lungs of mice immunized with the PR8-S virus as well as the homologous strain. The PR8-S virus was added as a constant component of the vaccine so that a high antibody titer to it would suppress selectively the development of variants with PR8-S characteristics. Comparative H.I. and in ovo neutralization tests with the first and second series of variants revealed that the three variants, Fd/s, Gf/s, and Hg/s, of the second series, failed to react with PR8-S antisera and produced significantly smaller amounts of antibody which reacted with PR8-S, the variants of the first series, and the first variant (D/s) of the second series. Although these three variants reacted quite similarly in the H.I. and neutralization tests cross-absorption of these sera with the PR8-S virus and themselves revealed individual antigenic characteristics. While these studies emphasize the importance of the immune state of the host the precise mechanism in the selection of a new antigenic component in the emerging variant must yet be determined.

Animals↗
PubMed2001

Jatobal virus is a reassortant containing the small RNA of Oropouche virus.

Jatobal (JAT) virus was isolated in 1985 from a carnivore (Nasua nasua) in Tucuruí, Pará state, Brazil and was classified as a distinct member of the Simbu serogroup of the Bunyavirus genus, family Bunyaviridae on the basis of neutralization tests. On the basis of nucleotide sequencing, we have found that the small (S) RNA of JAT virus is very similar (>95% identity) to that of Oropouche (ORO) virus, in particular, the Peruvian genotype of ORO virus. In comparison, limited nucleotide sequencing of the G2 protein gene, encoded by the middle (M) RNA, of JAT and ORO viruses, revealed relatively little identity (<66%) between these two viruses. Neutralization tests confirmed the lack of cross-reactivity between the viruses. These results suggest that JAT virus is a reassortant containing the S RNA of ORO virus. JAT virus was attenuated in hamsters compared to ORO virus suggesting that the S RNA of ORO virus is not directly involved in hamster virulence.

Amino Acid Sequence↗
PubMed2000

[Viral etiology study of acute conjunctivitis].

OBJECTIVE: To study the viral etiology of acute conjunctivitis broke out in Shenzhen in 1997. METHODS: Isolated the virus from eye and pharynx swabs of acute conjunctivitis in acute stage, and detected virus nucleic acid by polymerase chain reaction (PCR). DNA of viral strains were subjected to restriction enzyme analysis using several endonucleases. Also, neutralizing antibody of paired sera were detected. RESULTS: The positive virus isolation rates of 14 pharynx and eye swabs were 71.43% and 64.29%, respectively; and that of the virus DNA by PCR were 78.57% and 71.43%, respectively. All of the strains isolated were adenovirus type 3. Three paired viral strains chosen and subjected to restriction enzyme analysis proved belonging to Ad3a2 gene type. The neutralization test of paired sera of 24 cases showed that the antibody titers had 4 fold rising or above. Neutralization test of isolated viruses with paired sera of itself was carried out, the level of neutralizing antibody in convalescent stage was above 4 times as compared with that of acute stage. CONCLUSIONS: The results showed that the outbreak of acute conjunctivitis occurred in 1997 in Shenzhen was caused by adenovirus type 3.

Acute Disease↗
PubMed2003

Phenotypic and genotypic methods for the detection of herpes simplex virus serotypes.

Typing of herpes simplex virus (HSV) into its serotypes plays a major role in epidemiology and management of reactivation. To develop and evaluate a polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) was employed using Hae III and Taq I against neutralization test, allele-specific PCR and DNA sequencing for the detection of HSV serotypes. Neutralization test, allele-specific PCR, DNA sequencing and PCR-based RFLP were applied simultaneously to 2 standard strains (HSV-1 and HSV-2) and 23 clinical isolates. PCR-based RFLP was applied further to 20 culture negative PCR positive clinical specimens. The 179 bp product of the clinical isolates and specimens amplified using the type-common primers of HSV was subjected to DNA sequencing and PCR-based RFLP. Allele-specific PCR was absolutely specific and highly sensitive. All the typing methods differentiated concordantly 23 clinical isolates into 12 HSV-1 and 11 HSV-2. DNA sequencing did not reveal any nucleotide variations within the serotypes among the isolates sequenced. PCR-based RFLP typed a further 20 culture negative clinical specimens into 15 HSV-1 and 5 HSV-2. PCR-based RFLP was a reliable, less laborious and cost-effective molecular biological tool for the determination of HSV serotypes both for the clinical isolates and culture negative specimens.

Alleles↗
PubMed1978

Microneutralization tests for serological typing and subtyping of foot-and-mouth disease virus strains.

A microneutralization test for serotyping of FMD viruses is described. It is based on earlier observations by Booth, Rweyemamu & Pay (1978) that dose-response relationships in quantal microneutralizations often deviated from linearity. The typing test described therefore utilizes undiluted virus preparations. In about 90% of samples a positive typing was obtained in contrast with about 50% for the complement fixation test. The test was also found to be susceptible to minimal quantities of heterotypic viral contamination. For strain differentiation the microneutralization test was carried out as a checkerboard test. When compared with the complement fixation test it was found to be more specific. The necessity to utilize virus-neutralization test systems for comparing FMD virus strains particularly for the purpose of vaccine selection is emphasized. The two dimensional microneutralization test has been applied to a study of comparing FMDV vaccine strains for Europe, South America, the Middle East and East Africa.

Aphthovirus↗
PubMed1975

Isolation of La Crosse virus (California encephalitis group) from the chipmunk (Tamias striatus), an amplifier host.

La Crosse (LAC) virus was isolated from the blood of seven chipmunks (Tamias striatus) captured during the summer of 1970 in southwestern Wisconsin. With the exception of the original isolate obtained from human brain after fatal encephalitis, these represent the first known isolations of LAC virus from a naturally infected free-living vertebrate. The chipmunks were trapped and periodically recaptured in two study areas where 59 chipmunks became infected and developed neutralizing antibody during the summer cycle of virus transmission. All isolates were obtained from blood samples collected within a 7 week period between 11 July and 23 August, and all were from seronegative chipmunks; 6 of these were recaptured and found to be seropositive 2 to 3 weeks later. The isolates proved identical to each other in comparative micro-neutralization tests using BHK21 cell cultures and immune chipmunk serum or hyperimmune mouse ascitic fluids. Neutralization tests showed the isolates to be different from snowshoe hare, trivittatus, and Jamestown Canyon prototype virus strains but indistinguishable from the LAC prototype. Findings demonstrate multiplication and transmissibility of LAC virus in a naturally infected host and are consistent with the thesis that chipmunks are important amplifying hosts for LAC virus and that Aedes triseriatus mosquitoes serve as vectors in transmitting their infections. Ecological significance of the findings are discussed in regard to current perspectives.

Aedes↗
PubMed1981

Use of indirect immunofluorescence method for detection of rhinovirus-specific antibodies.

Neutralization test and the method of indirect immunofluorescence were used to study the titre of specific antibodies in 32 paired serum samples taken from subjects naturally infected by varying RV serotypes [1A, 1B, 9, 12, 15, 16, 19, 23, 26, 29, 30, 31, 41, 47]. The IF method was positive in all the examined sera, the increase in the titre of rhinovirus-specific antibodies was mostly low and in 10 cases was the titre in both serum samples identical. The neutralization test turned out to be less sensitive in detecting specific antibodies. In serum samples from 13 examined subjects it failed to detect antibody presence in either of the two serum samples, in 15 subjects was recorded an increase in the titre of antibodies, but in some of them was only small, and the identical antibody titre in both serum samples was detected in 4 subjects.

Adolescent↗
PubMed1988

Comparison of serologic assays for measurement of antibody response to coronavirus in cats.

Serologic virus neutralization tests, indirect immunofluorescence tests, and ELISA, using tissue culture-adapted feline infectious peritonitis virus (FIPV) or feline enteric coronavirus (FECV) were compared for their ability to distinguish specific virus exposure in cats. Sera of specific-pathogen-free cats inoculated with virulent or modified FIPV or FECV were used to compare the sensitivity and specificity of the homologous assays to a heterologous assay that measures antibody reactivity with transmissible gastroenteritis virus of swine. The geometric means of the serologic titers in FIPV and FECV assays were higher for FIPV- or FECV-infected specific-pathogen-free cats than the geometric means of the transmissible gastroenteritis virus assays for most groups. None of the assays was specific enough to discern the virus to which a cat had been exposed. However, the FIPV virus neutralization test appeared to be more sensitive for detection of an early response to FIPV infection than did the FIPV immunofluorescence test or FIPV-ELISA.

Animals↗