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PubMed1993

Reappraisal of modified neutralization test for Inoue-Melnick virus.

Ito et al. (1992) reported an improved modification of the neutralization (NT) test for Inoue-Melnick Virus (IMV) by prolonged 90 min incubation of the mixture of the virus and serum. For confirmation, we compared the results of the NT test by 90 and 60 min incubation. Against human sera, the NT test by 90 min incubation was significantly more sensitive than the test by 60 min incubation. By 90 min incubation, the NT titers increased by 3 to 6 times and approximately 6% of antibody-negative adult sera previously determined in the tests by 60 min incubation turned to positive (more than 1:10). However, antibody-negative sera of Japanese children examined previously in the tests by 60 min incubation remained negative after the 90 min tests. On the other hand, against rabbit immune sera, no significant difference of NT titers was observed between the two NT tests for 90 and 60 min incubation. Also we reinvestigated Japanese adult sera for type 2 IMV infection by the NT test for 90 min incubation, but did not find any serum of type 2 or intermediate type infection. Therefore, it is not necessary to change the previous conclusion that in Japan IMV infections are mostly of type 1.

Animals↗

PubMed1989

A rapid serum neutralization test in microplates for the detection of antibodies to hog cholera virus.

The fluorescent antibody serum neutralization (FASN) test for the detection of antibodies to hog cholera virus was developed utilizing 96-well and Terasaki microplates. This microtechnique, especially when performed in Terasaki plates, offers some advantage if compared with conventional FASN in coverslip cell cultures, being easier and more rapid, saving of reagents and allowing simple microscopic observation.

Animals↗

PubMed1990

Comparison between results of virus neutralization test and those of two ELISAs when screening for antibodies to pseudorabies virus in Thailand.

The virus neutralization (VN) test and two enzyme-linked immunosorbent assays (blocking and indirect ELISAs) were used to detect antibodies to pseudorabies virus on serum samples of 1,000 pigs from the central part of Thailand. The results of these tests were compared to those of VN test. Using the VN test as standard, the blocking and indirect ELISAs showed respectively 95.12% and 99.37% relative sensitivity and 92.0% and 93.5% relative specificity. The two ELISAs were considered both as practical alternatives to the VN test. However, the indirect ELISA was the more suitable test for the routine screening for antibodies to pseudorabies virus in Thailand.

Animals↗

PubMed2001

The use of intraallelic variability for testing neutrality and estimating population growth rate.

To better understand the forces affecting individual alleles, we introduce a method for finding the joint distribution of the frequency of a neutral allele and the extent of variability at closely linked marker loci (the intraallelic variability). We model three types of intraallelic variability: (a) the number of nonrecombinants at a linked biallelic marker locus, (b) the length of a conserved haplotype, and (c) the number of mutations at a linked marker locus. If the population growth rate is known, the joint distribution provides the basis for a test of neutrality by testing whether the observed level of intraallelic variability is consistent with the observed allele frequency. If the population growth rate is unknown but neutrality can be assumed, the joint distribution provides the likelihood of the growth rate and leads to a maximum-likelihood estimate. We apply the method to data from published data sets for four loci in humans. We conclude that the Delta32 allele at CCR5 and a disease-associated allele at MLH1 arose recently and have been subject to strong selection. Alleles at PAH appear to be neutral and we estimate the recent growth rate of the European population to be approximately 0.027 per generation with a support interval of (0.017-0.037). Four of the relatively common alleles at CFTR also appear to be neutral but DeltaF508 appears to be significantly advantageous to heterozygous carriers.

Alleles↗

PubMed1969

A serum neutralization test for infectious bovine rhinotracheitis based on colour reaction and cytopathic effects in cell culture.

A serum neutralization (SN) test based on a combination of indicator colour change in medium and cytopathic (CP) effect in cells has been devised for the detection of infectious bovine rhinotracheitis antibodies. Serum dilutions of 1:6, 1:18 and 1:54 are made in a medium containing phenol red and are mixed in equal quantities with a suspension of virus containing 100 cell culture infectious doses (CCID(50)) per volume of mixture. The serum-virus mixtures are held in small glass tubes and are covered with a layer of mineral oil. Following a two hour period of incubation at 37 degrees C a quantity of bovine fetal kidney cells is added to each tube to detect the presence of unneutralized virus. After four to six days incubation the results of the SN test may be read by microscopic examination for CP effect by means of an inverted microscope, or by observing the colour of the phenol red.

Culture Techniques↗

PubMed1988

Reevaluation of the western equine encephalitis antigenic complex of alphaviruses (family Togaviridae) as determined by neutralization tests.

Fourteen viruses closely related to the Fleming strain of western equine encephalitis (WEE) virus were cross-tested by serum dilution-plaque reduction neutralization. The results demonstrate that strains McMillan, R-43738, AG80-646, BeAr 102091, and Y62-33 are subtypes or varieties of western equine encephalitis virus strain Fleming. Ockelbo, Kyzylagach, and Babanki are subtypes of the prototype strain (EgAr 339) of Sindbis virus. Fort Morgan and Buggy Creek viruses are closely related to each other, whereas Highlands J and Aura viruses are distinct from other members of this antigenic complex. There appear to be parallels between geographic distribution and antigenic relatedness. We hypothesize that birds, the principal vertebrate hosts for these viruses, spread the progenitor viruses north and south and from continent to continent. Viruses of the WEE complex with lesser antigenic differences may develop in discrete ecologic conditions.

Alphavirus↗

PubMed1988

Cross-neutralization tests among Cache Valley virus isolates revealing the existence of multiple subtypes.

Maguari virus has been classified as a subtype of Cache Valley virus. Seven Bunyamwera serogroup viruses (including prototypes Cache Valley and Maguari viruses), 4 viruses shown in previous tests as close antigenic relatives of Maguari or Cache Valley viruses, and Xingu virus were cross-tested by serum dilution-plaque reduction neutralization. All viruses were distinguishable from prototypes Cache Valley and Maguari viruses. The close antigenic relationships of the Cache Valley-like viruses demonstrate that multiple subtypes of Cache Valley virus exist and suggest that such antigenic variation is a phenotypic expression of considerable genetic diversity.

Antigens, Viral↗

PubMed2002

Potential application of nonstructural protein NS1 serotype-specific immunoglobulin G enzyme-linked immunosorbent assay in the seroepidemiologic study of dengue virus infection: correlation of results with those of the plaque reduction neutralization test.

An NS1 serotype-specific indirect enzyme-linked immunosorbent assay (ELISA) was developed to differentiate primary and secondary dengue virus infections and serotypes of primary dengue virus infection. For this report, we carried out retrospective seroepidemiologic studies on serum samples collected from residents of Liuchiu Hsiang, Pingtung County, an isolated island in southern Taiwan during 1997-1998. The results demonstrated that good correlation existed between dengue virus NS1 serotype-specific immunoglobulin G (IgG) ELISA and dengue virus plaque reduction neutralization test (PRNT). Our data suggested that NS1 serotype-specific IgG ELISA could replace PRNT for seroepidemiologic studies to differentiate Japanese encephalitis and dengue virus infections and for dengue virus serotyping.

Adolescent↗

PubMed1964