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PubMed1994

Calibration of a replacement preparation for the International Standard for Rabies Immunoglobulin.

A proposed replacement preparation for the International Standard for Rabies Immunoglobulin was calibrated by means of two assay methods, a neutralization test in mice (MNT) and a neutralization test in cell culture (RFFIT). The calibration was made as an international collaborative assay comprising nine laboratories in eight countries. The results obtained in this study confirm earlier observations about occasional unexplainable differences between relative potencies obtained by the two methods. They also confirm the apparent reliability of the RFFIT. Based on the results obtained the proposed replacement preparation has been established as the second International Standard for Rabies Immunoglobulin with a defined unitage of 30 International Units of Rabies Antibodies in each ampoule.

Animals↗
PubMed2001

Short report: Antibody responses of mice immunized with a tetravalent dengue recombinant protein subunit vaccine.

Recombinant proteins containing the B domain of dengue virus serotypes 1-4 fused to the maltose binding protein (MBP) of Escherichia coli were evaluated individually and as a tetravalent vaccine candidate in mice. Sera from mice immunized with monovalent DEN-MBP recombinant protein vaccines developed high titers of serotype homologous antibody in the enzyme-linked immunosorbent assay and the plaque-reduction neutralization test. Cross-reactive antibody titers were either several dilutions lower or not detectable. Sera from mice immunized with the tetravalent DEN subunit vaccine neutralized all 4 DEN viruses in the plaque-reduction neutralization test. The neutralizing antibody titers to each individual serotype were significantly greater than any cross-reactive neutralizing antibody titers induced by the monovalent vaccines, providing evidence that the tetravalent DEN recombinant subunit vaccine produced specific neutralizing antibody to all 4 serotypes of dengue virus.

ATP-Binding Cassette Transporters↗
PubMed1982

Potentiation of neutralization of Varicella-Zoster virus to antibody to immunoglobulin.

Antibody to varicella-zoster virus was measured in Vero cell cultures by a conventional and an enhanced plaque neutralization test. In the latter, heterologous antibody to human immunoglobulin was added to the virus-serum mixture to potentiate the neutralization reaction. The antibody to human immunoglobulin enhanced the sensitivity of the neutralization test seven- to 107-fold as compared with the conventional procedure. The test was highly reproducible in that individual serum titers fluctuated in a twofold range on repeated testing. A prozone phenomenon was observed in the enhanced neutralization test in low-titered sera, but not with high-titered sera or with specimens of cerebrospinal fluid. The specificity of the test was confirmed by the detection of seroconversion in recipients of live varicella virus vaccine.

Animals↗
PubMed1996

New statistical tests of neutrality for DNA samples from a population.

The purpose of this paper is to develop statistical tests of the neutral model of evolution against a class of alternative models with the common characteristic of having an excess of mutations that occurred a long time ago or a reduction of recent mutations compared to the neutral model. This class of population genetics models include models for structured populations, models with decreasing effective population size and models of selection and mutation balance. Four statistical tests were proposed in this paper for DNA samples from a population. Two of these tests, one new and another a modification of an existing test, are based on EWENS' sampling formula, and the other two new tests make use of the frequencies of mutations of various classes. Using simulated samples and regression analyses, the critical values of these tests can be computed from regression equations. This approach for computing the critical values of a test was found to be appropriate and quite effective. We examined the powers of these four tests using simulated samples from structured populations, populations with linearly decreasing sizes and models of selection and mutation balance and found that they are more powerful than existing statistical tests of the neutral model of evolution.

Biological Evolution↗
PubMed1997

Statistical tests of neutrality of mutations against population growth, hitchhiking and background selection.

The main purpose of this article is to present several new statistical tests of neutrality of mutations against a class of alternative models, under which DNA polymorphisms tend to exhibit excesses of rare alleles or young mutations. Another purpose is to study the powers of existing and newly developed tests and to examine the detailed pattern of polymorphisms under population growth, genetic hitchhiking and background selection. It is found that the polymorphic patterns in a DNA sample under logistic population growth and genetic hitchhiking are very similar and that one of the newly developed tests, Fs, is considerably more powerful than existing tests for rejecting the hypothesis of neutrality of mutations. Background selection gives rise to quite different polymorphic patterns than does logistic population growth or genetic hitchhiking, although all of them show excesses of rare alleles or young mutations. We show that Fu and Li's tests are among the most powerful tests against background selection. Implications of these results are discussed.

Models, Genetic↗
PubMed2005

Isolation and characterization of H3N2 influenza A virus from turkeys.

Five 34-wk-old turkey breeder layer flocks in separate houses of 2550 birds each in a single farm in Ohio experienced a drop in egg production from late January to early February 2004. Tracheal swabs (n = 60), cloacal swabs (n = 50), and convalescent sera (n = 110) from the flocks were submitted to the laboratory for diagnostics. Virus isolation was attempted in specific-pathogen free embryonating chicken eggs and Vero and MDCK cells. Virus characterization was performed using agar gel immunodiffusion, the hemagglutination test, the hemagglutination inhibition test, the virus neutralization test, reverse transcription-polymerase chain reaction, sequencing, and phylogenetic analysis. A presumptive influenza virus was successfully propagated and isolated on the first passage in MDCK cells, but initially not in Vero cells or specific-pathogen free chicken embryos. After two passages in MDCK cells, it was possible to propagate the isolate in specific-pathogen free chicken embryos. Preliminary sequence analysis of the isolated virus confirmed that it was influenza A virus with almost 100% (235/236) identity with the matrix gene of a swine influenza A virus, A/Swine/Illinois/100084/01 (H1N2). However, it was not possible to subtype the virus using conventional serotyping methods. The results of genetic characterization of the isolated virus showed that it was the H3N2 subtype and was designated as A/Turkey/OH/313053/04 (H3N2). Phylogenetic analysis of the eight gene segments of the virus showed that A/Turkey/OH/313053/04 (H3N2) isolate was most closely related to the triple-reassortant H3N2 swine viruses [A/Swine/WI/14094/99 (H3N2)] that have been circulating among pigs in the United States since 1998, which contains gene segments from avian, swine, and human viruses. The A/Turkey/OH/313053/04 (H3N2) isolated from turkeys in this study was classified as a low pathogenic avian influenza A virus because it only caused a drop in egg production with minor other clinical signs and no mortality.

Animals↗
PubMed1996

Contingency tests of neutrality using intra/interspecific gene trees: the rejection of neutrality for the evolution of the mitochondrial cytochrome oxidase II gene in the hominoid primates.

Contingency tests of neutrality are performed using mitochondrial cytochrome oxidase II (COII) DNA sequences from hominoid primates, including humans. An intra-/interspecific haplotype tree is estimated, including a statistical assessment of ambiguities in tree topology and branch lengths. Four functional mutational categories are considered: silent and replacement substitutions in the transmembrane portion of the COII molecule, and silent and replacement substitutions in the cytosolic portion. Three tree topological mutational categories are used: intraspecific tips, intraspecific interiors, and interspecific fixed mutations. A full contingency analysis is performed, followed by nested contingency analyses. The analyses indicate that replacement mutations in the cytosolic portion are deleterious, and replacement mutations in the transmembrane portion and silent mutations throughout tend to be neutral. These conclusions are robust to ambiguities in tree topology and branch lengths. These inferences would have been impossible with an analysis that only contrasts silent and replacement vs. polymorphic and fixed. Also, intraspecific interior mutations have similar evolutionary dynamics to fixed mutations, so pooling tip and interior mutations into a single "polymorphic" class reduces power. Finally, the detected deleterious selection causes lowered inbreeding effective sizes, so arguments for small effective sizes in recent human evolutionary history based upon mitochondrial DNA may be invalid.

Animals↗
PubMed1994

An exact test for neutrality based on the Ewens sampling distribution.

Using the Ewens sampling distribution of selectively neutral alleles in a finite population, it is possible to develop an exact test of neutrality by finding the probability of each configuration with the same sample size and observed number of allelic classes. The exact test provides the probability of obtaining a configuration with the same or smaller probability as the observed configuration under the null hypothesis. The results from the exact test may be quite different from those from the Ewens-Watterson test based on the homozygosity in the sample. The advantages and disadvantages of using an exact test in this and other population genetic contexts are discussed.

Alleles↗
PubMed2004

A classical live attenuated vaccine for sheep pox.

A classical live attenuated sheep pox vaccine was prepared using the Ranipet strain of sheep pox virus (SPV) at the 50th passage in a secondary lamb testicular cell system. The TCID50 and RD50 were 10(9.63)/ml and 10(9.51)/ml. respectively. The SID50 of SPV challenge virus was 10(5)/ml. The vaccine was found to have no adverse effects in laboratory animals, and was safe and effective in SPV seronegative lambs. In the field, 660 sheep were vaccinated with an immunizing dose containing 1 x 10(2) TCID50. Randomly selected vaccinated sheep mounted good cell-mediated immunity and humoral responses as measured by glucose utilization test and serum neutralization test, respectively, for the study period of 6 months.

Animals↗
PubMed1986

Purification and partial characterization of a non-O1 Vibrio cholerae hemolysin that cross-reacts with thermostable direct hemolysin of Vibrio parahaemolyticus.

A newly identified hemolysin (NAG-rTDH), which is related to the thermostable direct hemolysin (Vp-TDH) of Vibrio parahaemolyticus produced by non-O1 Vibrio cholerae, was studied. NAG-rTDH was purified by successive column chromatographies on DEAE-cellulose and an immunoaffinity column coupled with anti-Vp-TDH immunoglobulin. The molecular weight of NAG-rTDH was estimated as 18,500, similar to that of Vp-TDH, as judged by sodium dodecyl sulfate slab gel electrophoresis, but its charge or molecular shape was different, judging from its electrophoretic mobility. The lytic activities of NAG-rTDH on erythrocytes of most animals were essentially similar to those of Vp-TDH, but that on sheep erythrocytes was different. The hemolytic activity of NAG-rTDH was stable on heating at 100 degrees C for 10 min, as was that of Vp-TDH. Immunological cross-reactivity between NAG-rTDH and Vp-TDH was demonstrated by both the Ouchterlony test and the neutralization test. Thus, we conclude that non-O1 V. cholerae produce a new type of hemolysin that is similar but not identical to the thermostable direct hemolysin of V. parahaemolyticus.

Cross Reactions↗
PubMedDate not supplied

[Outcomes and prognosis of diseases caused by Inkoo and Tahyna viruses].

The outcomes of diseases caused by Inkoo and Tahyna viruses are favorable. No lethal cases were observed. Altogether 16.7% of convalescents after the febrile form of the disease and 30.7% convalescents after the neuroinfections form develop 1 to 2.5 years after the disease (follow-up period) asthenoneurologic disturbances and microfocal neurologic symptoms. Blood sera of 118 patients with chronic neurologic diseases were tested in the neutralization test with Inkoo and Tahyna viruses. Summary antibodies to Inkoo and Tahyna viruses were detected in 26 (70.3%) of 37 examined patients with disseminated encephalomyelitis. The findings point to necessity of further study of the possible role of California encephalitis group viruses in the etiology of chronic neuroviral infections.

Antibodies, Viral↗
PubMed2001

Antibody testing against canine coronavirus by immunoperoxidase plaque staining.

The application of the immunoperoxidase (IP) plaque staining procedure (IP test) to the diagnosis of canine coronavirus (CCV) infection was investigated. The IP test did not react with sera from either 15 specific pathogen-free (SPF) dogs or 7 SPF dogs immunized with a multivalent vaccine, including canine parvovirus type 2, canine distemper virus, canine adenovirus type 2, and canine parainfluenza virus. To compare the IP test with the neutralizing test (NT), sera from 240 healthy dogs and from 3 experimentally CCV-infected dogs were examined. All 60 sera positive for NT antibody were positive for IP antibody, and all 180 sera negative for NT antibody were negative for IP antibody in the healthy dogs. The IP titres showed similar changes with time after CCV inoculation to those of the NT titres in the experimentally infected dogs. These findings indicate that the IP test specifically detected anti-CCV antibodies. When the IP test and NT were compared in dogs with diarrhoeic signs. 2.1% of 48 sera and 20.3% of 74 sera, which were all negative for NT antibody, were positive for IP antibody in the dogs of under one year of age and at least one year of age, respectively. The difference between the IP and NT titres (log10 [reciprocal of IP titre] log10 [reciprocal of NT titre]) for the diarrhoeic dogs of under one year of age (2.350 +/- 0.931) was significantly larger than that for the healthy dogs (0.982 +/- 0.447) (p<0.0001), the NT titre being negative or very low, despite a high IP titre in many diarrhoeic dogs. Hence, the IP test is more able to detect anti-CCV antibodies, especially in dogs showing clinical signs. The IP-positivity rate was significantly higher in the diarrhoeic dogs of under one year of age (48.7%) than in the healthy dogs (25.0%) (chi2 = 19.844, p<0.0001), suggesting that CCV may contribute to diarrhoea in many juvenile dogs.

Animals↗
PubMed1987

[Evaluation of the results of the ELISA reaction in the serologic diagnosis of bovine leukosis].

Blood serum samples collected from two cattle herds were examined by the immunodiffusion test (ID), pseudotype neutralization test (PsNT) and ELISA procedure for the presence of antibodies to the bovine leukosis virus. The spectrophotometric readings of the ELISA procedure were evaluated on the basis of the arithmetical mean (means) and standard deviation (Sd) of the values obtained in negative controls. The examination of 208 samples of serums taken in the negative herd confirmed in all cases a negative reaction in the ID and PsNT tests. In all samples the ELISA reaction values remained within the range delimited by the relation of means + 3 Sd, which was defined as the threshold value of positive reaction. Out of the 223 serum samples of the positive herd, 132 samples were within the range below means and five of them were leukosis-positive in PsNT. Twenty-nine samples were within the range of means to means + 3 Sd; five of them were found positive in PsNT and three in the ID test. Sixty-two samples were above the threshold value of positivity; of these, positivity was confirmed in 58 cases by PsNT and in 55 cases by ID. As the results suggest, the ELISA procedure is suitable for the detection of animals positively reacting to bovine leukosis, to which special attention should be paid.

Animals↗
PubMed2003

Antigenic characterization of foot-and-mouth disease virus serotype Asia1 field isolates using polyclonal and monoclonal antibodies.

Foot-and-mouth disease virus (FMDV) serotype Asia1 field isolates (n = 100) were compared using a panel of 11 monoclonal antibodies (Mab) in sandwich ELISA. The majority (over 89%) of the isolates showed either homologous (76% and above reactivity) or reduced affinity (20-75% reactivity) for the Mabs 2A, 13, 40, 34 and 81, suggesting that these Mab binding epitopes are conserved, whereas a more variable reactivity was observed for the Mabs B3, 1A, 24, 72, 82 and 89. Polyclonal relationship ('r' value) of the field isolates in liquid phase blocking (LPB) ELISA was examined, and the mean 'r' value was 0.62 relative to vaccine virus IND 63/72. Some of the field isolates (n = 34) were tested in virus neutralization test (VNT) and showed an 'r' value of >0.40. Although a minor antigenic difference was observed in the Mab profiling study, there has not been large antigenic divergence between reference virus and field viruses, thereby providing evidence of wide antigenic coverage of the vaccine strain.

Animals↗
PubMed2003

Report of the Meningitis Program of the International Scientific Working Group on TBE. Serological screening of patients with viral CNS-infection of unknown etiology in search of undiagnosed TBE cases.

The endemicity of tick-borne encephalitis (TBE) in Europe is changing. Potential undetected or emerging TBEV foci and the risk of underdiagnosis due to a low awareness among the medical community form the background of this retrospective multicenter follow-up study. We investigated the possibility of undiagnosed TBE cases among patients with presumed viral central nervous system (CNS)-infection of unknown etiology. Eight centers in four European countries provided sera and/or cerebrospinal fluid (CSF) samples from 233 individuals. The samples were screened with a commercial TBEV ELISA test system (IgM and IgG). Positive or borderline samples were re-evaluated at the Institute of Virology in Vienna by an in-house ELISA test and a neutralization test (NT). Two previously undiagnosed Swedish TBE patients were verified. Three additional individuals from Swedish centers were IgG ELISA and NT positive. No NT positive individuals were found from France, Belgium or The Netherlands. Nineteen individuals were found IgG TBE ELISA positive, but negative in NT, indicating unspecific reactivity. At least four of those patients were vaccinated against yellow fever. The probable reason for the reactivity seen in these individuals is the well-known cross-reactivity existing among flaviviruses.

Antibodies, Viral↗
PubMed1978

Plastic multiwell plates to assay avian infectious bronchitis virus in organ cultures of chicken embryo trachea.

Simple assay systems for infectivity titrations of avian infectious bronchitis virus (IBV) in chicken embryo trachea organ cultures (OC) were developed using plastic multiplate wells with one tracheal ring per well; these assays appeared to be much more satisfactory than the conventional rolled-tube method. The medium, 0.05 M HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid)-buffered Eagle minimal essential medium was not changed during observation. A medium containing 0.4% bovine serum albumin did not influence the virus yield, but did stabilize virus viability during storage. Reproducibility of results obtained in the OC system was confirmed by performing replicate titrations of the Beaudette strain with three different passage histories. The mean virus titers in the OC were lower than those in chicken embryos, depending on the IBV passage histories. The time required for ciliostasis was related not only to the concentration of virus, but also to the IBV passage history. Application of OC techniques for the constant serum-variable virus neutralization test gave low neutralization indexes with excellent reproducibility as compared with those obtained in the chicken embryo assay system. Also, the slopes of neutralization curves obtained by assays in OC were less steep than those seen in the chicken embryo system.

Animals↗
PubMed1979

Antigenic comparisons between herpesviruses isolated from fallow deer in Alberta and the viruses of infectious bovine rhinotracheitis, equine rhinopneumonitis and DN-599, a non-IBR bovine herpesvirus.

Antigenic comparison studies of three herpesviruses isolated from fallow deer (Dama dama) in Alberta and herpesviruses from some domestic species were carried out by the alpha serum-virus neutralization test. Complete cross neutralization was demonstrated among the deer herpesviruses and equine herpesvirus type 1.

Alberta↗
PubMed1992

[A comparison of the effectiveness of mass immunization campaign of trivalent oral poliovirus vaccine (TOPV) by epidemiological serosurvey. Shandong Collaborating Group for Poliomyelitis Control and Surveillance, Jinan, Shandong].

In order to evaluate the effect of TOPV mass immunization campaign, 902 serum samples from two counties of Shandong province were assayed by micro-neutralization test for the neutralization antibodies against poliovirus. The results showed that among children of 0 to 9 year-old groups, the antibody-positive rates and geometric mean titres (GMTs) with poliovirus type 1 to 3 after mass immunization campaign were significantly higher than those before the campaign, respectively. The author considers that it is necessary for poliomyelitis eradication to carry out TOPV mass immunization campaign on the basis of EPI routine immunization.

Antibodies, Viral↗