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PubMed1990

Antibodies to Aujeszky's disease virus in pigs immunized with purified virus glycoproteins.

Antibodies to Aujeszky's disease virus (ADV) glycoproteins gII, gIII, and gp50 were compared using four in vitro tests. Antibodies generated by vaccination with a modified-live vaccine (MLV) were also compared. The serological assays employed were: serum neutralization test (SNT), complement facilitated serum neutralization test (C'SNT), complement-mediated cytolysis and antibody dependent cellular cytotoxicity (ADCC). Pigs were immunized with single glycoproteins twice 14 days apart, or once with the modified-live vaccine. Fourteen days after the second immunization, sera were collected. Virus neutralizing activity (SNT) was demonstrated in the sera from all pigs immunized with gp50 and in one out of three immunized with gIII. Sera from the MLV group all had neutralization titers higher than animals immunized with single glycoproteins. Addition of guinea pig complement to the serum neutralization test (i.e., C'SNT) produced an enhancement of antibody titers in all groups except the pigs immunized with gIII. The complement-mediated cytolysis test rendered antibody titers similar in magnitude for all pigs immunized with single glycoproteins, but slightly lower than values for MLV vaccinated pigs. ADCC activity was clearly displayed in sera from pigs immunized with gIII or vaccinated with MLV, whereas sera from pigs immunized with gII or gp50 had a minimal response. The results indicate that the relative efficiency of antibodies against ADV glycoproteins in protection should be considered for selecting or producing gene-deleted strains for use in vaccine production.

Animals↗
PubMed1979

Enzyme-linked immunosorbent assay for serology of infectious bovine rhinotracheitis virus infections.

An enzyme-linked immunosorbent assay was developed to detect antibodies to infectious bovine rhinotracheitis virus in bovine sera. The test used viral antigen purified in a sucrose density gradient, and the antibody titers detected were up to 100 times higher than those seen in the serum neutralization test. When 250 sera were tested by those two tests, 146 were positive and 49 were negative in both tests. Only 1 serum was negative in the immunoassay test and positive in the neutralization test. However, 54 sera negative in the neutralization test were positive in the immunoassay test. These positive results appear to be in agreement with the increased sensitivity of the enzyme immunoassay.

Animals↗
PubMed1976

A stable antibody-sensitized erythrocyte diagnostic preparation for detection of rhinovirus type 17 and its antibody.

A diagnostic preparation was obtained by sensitization of formalinized sheep erythrocytes with antibody to rhinovirus type 17. This preparation was agglutinated in the presence of relatively high concentrations of type 17 but not other types of rhinovirus. It could also be used for detection of antibody to rhinovirus type 17 in the antigen neutralization test, the antibody levels determined in this way being similar to those found by conventional virus neutralization tests in cell cultures.

Animals↗
PubMed1978

An indirect fluorescent antibody test for antibodies to transmissible gastroenteritis of swine.

The indirect fluorescent antibody test was modified to provide a rapid technique for the detection, screening and titration of antibodies to transmissible gastroenteritis of pigs. Large numbers of slides containing transmissible gastroenteritis antigen were prepared by planting mixtures of infected and uninfected swine testicular cells onto multiwelled teflon-coated slides. After overnight incubation, about one-half of the cells in each well were infected which provided contrast to aid in detecting specific fluorescence in the presence of varying degrees of background staining. Following fixation, antigen slides were stored at -20 degrees C until used. The indirect fluorescent antibody test was compared to the virus neutralization test in both the screening and titration of swine sera containing transmissible gastroenteritis antibodies. The test was found to be sensitive and reliable and to offer certain advantages over the virus neutralization test.

Animals↗
PubMed1975

Antigenic properties of the arenaviruses.

Arenaviruses are known to show antigenic relationships in the complement-fixation (CF) and fluorescent antibody tests but not in the neutralization test. The humoral response to some of the arenaviruses is characterized by a dissociation between the antibodies determined by the CF test and those determined by the neutralization test and also by its late appearance following natural infection. Investigations are reported showing that, as regards the CF test, Junin, Machupo, Amapari, and Tacaribe viruses are closely related, while LCM and Lassa viruses are distantly related to each other and to the remaining viruses in the group. Studies by agar gel diffusion and precipitation have shown complete specificity except among viruses that are very closely related in the CF test. Observations with sera from persons infected with Lassa fever virus show that CF antibodies rarely appear before the 18th day after onset; they can persist, with diminishing titres, for up to 6 years.

Animals↗
PubMed1979

Quantification of tetanus antitoxin in human sera. II. Comparison of counter-immunoelectrophoresis and passive haemagglutination with toxin neutralization in mice.

We described recently an improved counter-immunoelectrophoretic method for quantification of tetanus antitoxin. The toxin neutralization test in mice is considered to correlate well with protection in humans. In the present study, the correlation coefficient between the two methods was 0.89. Sera containing more than 7.0 I.U./ml could be quantified directly by counter-immunoelectrophoresis, while sera containing less tetanus antitoxin had to be concentrated prior to quantification. The passive haemagglutination test was also compared with the toxin neutralization test in mice. The correlation coefficient between the two methods was 0.76.

Antibodies, Bacterial↗
PubMed1971

Antigenic relationship between influenza B viruses.

The object of this study was to determine whether antigenic groupings exist among influenza B viruses. Altogether, 22 influenza type B strains isolated during the years 1940-68 were examined by reciprocal haemagglutination-inhibition, strain-specific complement-fixation, and serum neutralization tests with sera produced in ferrets and guinea-pigs. It was found that the strain-specific complement-fixation test was superior for separating influenza B viruses into groups whereas the haemagglutination-inhibition and serum neutralization tests were better for demonstrating similarities. The results obtained with these three immunological techniques confirmed that antigenic variation exists among influenza B viruses, although it is not as clearcut as among influenza A viruses.The results were subjected to numerical taxonomic analysis. Dendrograms and minimum-spanning trees were constructed, using methods based on cluster analysis of similarity coefficients. Four main groups of influenza B viruses were established, although they were all interlinked. The results of this study do not justify the separation of influenza B viruses into subtypes similar to those of influenza A viruses.

Antigens↗
PubMed1986

Isolation of a new rhabdovirus in Australia related to Tibrogargan virus.

A virus isolated from the blood of a healthy steer and designated DPP53 was shown to have rhabdovirus morphology. Although DPP53 virus was antigenically related to Tibrogargan virus by reciprocal immunofluorescence and neutralization tests, the viruses were distinguishable by neutralization tests. DPP53 virus contained RNA and was sensitive to both ether and chloroform. The geographical distribution of neutralizing antibody to DPP53 virus in Australian cattle corresponded to the distribution of Culicoides brevitarsis indicating that this virus may be arthropod-borne with this midge as a possible vector. Antibody to DPP53 virus was detected in serum from cattle, buffalo, dogs and one horse, but not in serum from deer, pigs, humans or wallabies. Highest virus titres were obtained by growth in Vero and BHK21 cell cultures, but the virus could also be grown in Aedes albopictus cell cultures. Higher virus titres were obtained when the multiplicity of infection was low. The name advanced for DPP53 virus is 'Coastal Plains' virus.

Animals↗
PubMed1998

Paramyxoviral and reoviral infections of iguanas on Honduran Islands.

Thirty-five free-ranging healthy spiny-tailed iguanas (31 Ctenosaura bakeri, 4 C. similis) and 14 green iguanas (Iguana iguana rhinolopha) were caught and held in captivity for 2 days. Blood was collected from all animals and their sera were evaluated for antibody titres against reptilian reoviruses, reptilian paramyxoviruses, and avian paramyxovirus-1 (PMV-1). Cloacal and pharyngeal swabs also were collected and examined for viral content by incubation on chicken embryo fibroblasts (CEF) and terrapene heart cells (TH-1). No virus was isolated from the pharyngeal and cloacal swabs on CEF and TH-1. Twenty-three (47%) of 49 sera samples tested positive for reptilian reoviruses by virus neutralization tests. Twenty (41%) of 49 samples had antibodies against one reptilian PMV isolate by virus neutralization tests and 3 (9%) of 34 by hemagglutination inhibition tests. No antibodies were detected against the other PMV isolate of reptilian origin nor against avian PMV-1. This is the first description of serum antibodies against reptilian reoviruses and PMV in wild iguanas.

Animals↗
PubMed1978

Differentiation between specific and nonspecific reactions of bovine sera and foot and mouth disease virus (FMDV) in immunodiffusion tests.

The precipitating and neutralizing activities of normal bovine sera with FMDV were studied and compared. Twenty-two out of 79 normal bovine sera gave a positive reaction in micro neutralization tests with FMDV type O, while six did so with type A. In RID tests 32 sera were positive with type O and 28 with type A virus. Almost all of the 79 sera gave a positive reaction in the RID with trypsin treated virus of both types. After three to four fold concentration most sera also gave visible reactions in ID tests when tested against complete virus. When O virus was used the ID patterns produced by most normal sera clearly differed from those obtained with early and late convalescent sera from FMDV infected steers. When type A materials were employed this was also the case but to a lesser extent. The patterns obtained with concentrated normal sera showed, in general a strong line with trypsin treated virus and no line or a weaker one with complete virus. The substances in normal bovine sera precipitating trypsin treated O virus were different from those reacting with trypsinized virus of type A.

Animals↗
PubMed1985

Diagnosis of Colorado tick fever virus infection by enzyme immunoassays for immunoglobulin M and G antibodies.

An immunoglobulin M (IgM) capture enzyme immunoassay technique was adapted for the detection of antibody to Colorado tick fever virus in sera from 84 individuals for whom diagnosis had been confirmed by virus isolation or neutralization test. Titers were compared with those for IgG and neutralizing antibodies in these Colorado tick fever cases. IgM antibody titers were higher than neutralizing antibody titers, but neither appeared until 1 to 2 weeks after the onset of illness. Neutralizing antibodies were detected earlier than IgM antibodies, and both were detected with greater frequency than IgG antibodies. Late-convalescent-phase sera contained both neutralizing and IgG antibodies, but IgM was all but undetectable by 2 months after onset. Although the neutralization test may remain the serological test of choice, the enzyme immunoassay for IgM antibody offers a simple and more rapid method of serodiagnosis; the enzyme immunoassay is, however, less sensitive than the neutralization test. Furthermore, because there was a sharp decline in IgM antibody after 45 days, the presence of IgM antibody in a single serum sample provides a basis for the presumptive serodiagnosis of recent Colorado tick fever virus infection.

Adolescent↗
PubMed2002

Hantaviruses in Estonia.

Human serum samples collected from healthy individuals in 14 counties were screened by ELISA in order to investigate the presence of hantavirus infections in Estonia. Out of 1,234 serum samples, 124 were found positive for hantavirus-specific IgG and were subsequently serotyped by a focus reduction neutralization test. A total of 112 samples neutralized at least one of the examined hantaviruses-Puumala (PUUV), Saaremaa (SAAV), Dobrava (DOBV), Hantaan, and Seoul viruses-and thereby, the focus reduction neutralization test confirmed the overall hantavirus seroprevalence rate in Estonia to be 9.1%. Most of the sera showed a specific reaction (at least 4-fold higher endpoint titer) of neutralizing antibodies to PUUV (5.1%), while 3.4% showed a SAAV- or SAAV/DOBV-specific reaction. The fact that seven sera (0.6%) could not be serotyped may indicate the presence of an unknown hantavirus serotype. Hantavirus infections were confirmed in 13 of 14 investigated counties, with highly varying seroprevalence rates (1.0-28.4%). The sex ratio was 1.8:1.0 (M:F), and the antibody prevalence peaked in the age group 45-54 years. A total of 513 rodents of seven species trapped in seven counties were examined for the presence of hantavirus antigen, in order to study the distribution of hantavirus natural carriers. Two species, Clethrionomys glareolus and Apodemus agrarius, were found positive for hantaviral antigen in 13.7% and 4.5% of the investigated rodents, respectively. Analyses of viral sequences recovered from infected C. glareolus tissue samples showed that the infecting virus belonged to the PUUV genotype, confirming that PUUV circulates in mainland Estonia. The Estonian PUUV strains were placed in the closest proximity to Russian PUUV strains in phylogenetic trees, suggesting a common evolutionary history. Together with earlier data on SAAV in A. agrarius, the results revealed that two hantaviruses, PUUV and SAAV, are common in Estonia and that the incidence of human infection is high in both cases.

Animals↗
PubMed2000

Diversity of infectious pancreatic necrosis virus strains isolated from fish, shellfish, and other reservoirs in Northwestern Spain.

A comparison was done of 231 strains of birnavirus isolated from fish, shellfish, and other reservoirs in a survey study that began in 1986 in Galicia (northwestern Spain). Reference strains from all of the infectious pancreatic necrosis virus serotypes were included in the comparison, which was done by neutralization tests and agarose and polyacrylamide gel electrophoresis of the viral genome. The neutralization tests with antisera against the West Buxton, Spajarup (Sp), and Abild (Ab) strains showed that most of the Galician isolates were European types Sp and Ab; however, many isolates (30%) could not be typed. Results from agarose gels did not provided information for grouping of the strains, since all were found to have genomic segments of similar sizes. Analysis of polyacrylamide gels, however, allowed six electropherogroups (EGs) to be differentiated on the basis of genome mobility and separation among segments, and a certain relationship between EGs and serotypes was observed. A wide diversity of electropherotypes was observed among the Galician isolates, and as neutralization tests showed, most of the isolates were included in EGs corresponding to European types Ab and Sp. Only 6.5% of the isolates had the electropherotype characteristic of American strains.

Animals↗
PubMed1992

Comparability of poliovirus neutralizing antibody tests.

A serology panel was used to assess the comparability of results of poliovirus neutralizing antibody assays. Five laboratories from three countries provided results with seven in-house methods. A high degree of within-laboratory reproducibility was seen for all laboratories and methods, with 94% of results for repeat titrations within plus or minus one twofold dilution. Considerable differences in sensitivity between methods were, however, observed. The period of serum/virus incubation prior to inoculation of cells was shown by one laboratory to have a 10-fold effect on titres, and another laboratory showed that use of Sabin or wild-type challenge virus significantly influenced results for types 1 and 3. Expression of results as relative potencies abolished these difference due to method. The difference in sensitivity between laboratories for end-point titres (if one very sensitive method was excluded) was around fourfold for types 1 and 2, and ninefold for type 3. This range increased to 15-fold for type 2; and 20-fold for types 1 and 3 if the most sensitive method was included. Expression of results relative to a standard considerably improved agreement with a residual variation of around fourfold. Therefore, expression of results from serological studies, including vaccine trials, in International Units (i.e. relative to the new International Standard) will assure that comparisons between studies can be made with confidence.

Animals↗
PubMed1979

Relationships of bunyamwera group viruses by neutralization.

A standardized serum dilution plaque reduction neutralization test was used for cross-neutralization studies of 23 strains of Bunyamwera serogroup viruses. Antigenic relationships were determined by inspection of the neutralization tests results as well as by numerical taxonomic analysis. Based on these analyses five complexes, containing 1-11 viruses, were distinguished. Little or no cross-reactivity was observed between viruses of different complexes. Three of the viruses tested were indistinguishable from prototypes and probably represent strains or varieties of those prototypes. A tentative classification scheme for the Bunyamwera group is presented.

Antigens, Viral↗
PubMed1978

Serologic distribution of antibodies against adenoviruses in sheep of large-scale farms.

The common soluble antigen of the first subgroup of bovine adenoviruses was used for assaying 793 sheep sera by the agar gel diffusion test. Of the 50 farms included in the study 43 were found infected. The ratio of reacting samples was 73.7% of the sera obtained from infected farms. Virus neutralization tests revealed that a considerable number of sera reacted specifically with all types of ovine adenoviruses, even with serotypes which had never been isolated in Hungary. The results yielded by the agar gel diffusion tests were compared with the results of virus neutralization tests. Of 850 cattle serum samples, agar gel diffusion tests gave positive results in 33.4%. Virus neutralization test was done only with the bovine and adenovirus type 2. No differences could be detected in antibody titres when the prototype strains (No. 19) and the strain isolated from sheep (ORT/111) were compared in parallel titrations. Both ruminant species were found to be infected with hovine adenovirus type 2. Neverthless, inapparent infection with these strains seemed to be less frequent among cattle than in sheep flocks.

Adenoviridae↗
PubMed2004

Pestivirus exposure in free-living and captive deer in Austria.

During the hunting season of 2001-02, blood and spleen samples from 59 red deer (Cervus elaphus), 77 roe deer (Capreolus capreolus), four fallow deer (Dama dama), and five chamois (Rupicapra rupicapra) were collected from nine hunting districts (n = 133) and one deer farm (n = 12) in southern Austria. Sera were tested for antibodies against bovine viral diarrhea virus (BVDV) with an enzyme-linked immunosorbent assay (ELISA) and virus neutralization tests against three BVDVs and one border disease virus strain. Reverse transcriptase polymerase chain reaction was used for detection of pestivirus-specific RNA in spleen samples. Antibodies were detected in one serum sample when using ELISA and virus neutralization tests. Results of the virus neutralization tests of this sample provided strong evidence for the exposure to the BVDV-1 genotype. The spleen samples were negative for pestivirus-specific RNA.

Animals↗