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PubMedDate not supplied

Characteristics of CVI988/Rispens and R2/23, two prototype vaccine strains of serotype 1 Marek's disease virus.

Studies were focused on two attenuated serotype 1 Marek's disease (MD) vaccine viruses, CVI988/Rispens (passage 42) and R2/23 (passage 105). Both serotype 1 vaccine viruses provided much higher levels of protection than the prototype MD vaccine, turkey herpesvirus (HVT); the best protection was generally provided by CVI988/Rispens when compared with other vaccines. The efficacy of neither serotype 1 vaccine was improved by mixture with viruses of other serotypes (synergism). No differences between the two serotype 1 vaccines were revealed by cross-neutralization tests, thus excluding preferential in vivo neutralization by maternal antibodies as an explanation for differences in protective efficacy. Neither vaccine strain induced MD lesions or reduced growth rates in 8- or 18-week trials. Neither virus depressed humoral or cellular immune responses to antigenic challenge at 3 or 15 days after vaccination. Both virus strains exhibited altered characteristics during serial backpassage; R2/23 acquired increased oncogenic potential, and CVI988/Rispens acquired the potential for increased viremia titers, accompanied by an increased frequency of both histologic nerve lesions and gross thymic atrophy. During backpassage trials, contact spread was not observed for R2/23 and, surprisingly, seemed relatively limited for CVI988/Rispens. Studies on these two serotype 1 strains generally support the safety and efficacy of the serotype 1 class of MD vaccines.

Animals↗
PubMed1978

[Effectiveness of the tularemia-antibody erythrocyte diagnostic agent for the detection of specific antigen and antibodies to it].

The authors demonstrated the efficacy of utilization of tularemia antibody erythrocytic diagnostic agent. Data are presented indicating a strict specificity and a high sensitivity of this diagnostic agent for detection of the Vi-antigen both in the tularemia microbe cultures and in the suspensions of the organs of rodents which perished of tularemia, irrespective of the state of cadaver. There was revealed relationship between the sensitivity of the diagnostic agent and the virulence of the tularemia microbe cultures. A possibility of using the diagnostic agent in the antigen neutralization test for detection of specific antibodies in the sera of patients, who sustained the disease, and of the vaccinated humans and animals was revealed.

Animals↗
PubMed1980

Serological reactions of fractionated hamster immunoglobulins with California group viruses.

Immunoglobulin M and immunoglobulin G (early and late) were separated by sucrose density gradient centrifugation from single inoculation hamster immune sera prepared against La Crosse, California encephalitis and snowshoe hare viruses. Fractionated antibodies were tested for differences in serological specificity by hemagglutination-inhibition, neutralization, and complement-fixation reactions. None of the immunoglobulins demonstrated a consistent pattern of superior specificity in serological reactions with closely related California group viruses. Results were most uniform in the neutralization test in that immunoglobulin M and early and late immunoglobulin G all showed similar cross-reactivities. By hemagglutination-inhibition and complement-fixation, a given immunoglobulin type from one serum would show good specificity while the same type from another serum would be quite cross-reactive. Immunoglobulin M neutralizing antibody fractions fixed complement as effectively as late immunoglobulin G neutralizing antibody fractions. Unlike results obtained by others with flavivirus immune sera, the immunoglobulin M fractions from California group immune sera were not more specific than immunoglobulin G fractions by neutralization, hemagglutination-inhibition, or complement-fixation tests. Single inoculation hamster antisera, prepared to California group viruses and collected late (28-30 days), were as specific in the neutralization test as antisera collected early (7-10 days).

Animals↗
PubMed1999

Evaluation of the baculovirus-expressed S glycoprotein of transmissible gastroenteritis virus (TGEV) as antigen in a competition ELISA to differentiate porcine respiratory coronavirus from TGEV antibodies in pigs.

The spike (S) glycoprotein of the Miller strain of transmissible gastroenteritis virus (TGEV) was recently cloned and expressed in baculovirus. The recombinant S protein was used as the coating antigen in a competition (blocking) enzyme-linked immunosorbent assay (ELISA) in combination with monoclonal antibodies to the S protein epitope A (conserved on TGEV and porcine respiratory coronavirus [PRCV]) or epitope D (present on TGEV only) to differentiate PRCV- from TGEV-induced antibodies. One set (set A) of 125 serum samples were collected at different times after inoculation of caesarean-derived, colostrum-deprived (n = 52) and conventional young pigs (n = 73) with 1 of the 2 porcine coronaviruses or uninoculated negative controls (TGEV/PRCV/negative = 75/30/20). A second set (set B) of 63 serum samples originated from adult sows inoculated with PRCV and the recombinant TGEV S protein or with mock-protein control and then exposed to virulent TGEV after challenge of their litters. Sera from set A were used to assess the accuracy indicators (sensitivity, specificity, accuracy) of the fixed-cell blocking ELISA, which uses swine testicular cells infected with the M6 strain of TGEV as the antigen source (ELISA 1) and the newly developed ELISA based on the recombinant S protein as antigen (ELISA 2). The sera from set B (adults) were tested for comparison. The plaque reduction virus neutralization test was used as a confirmatory test for the presence of antibodies to TGEV/PRCV in the test sera. The accuracy indicators for both ELISAs suggest that differential diagnosis can be of practical use at least 3 weeks after inoculation by testing the dual (acute/convalescent) samples from each individual in conjunction with another confirmatory (virus neutralization) antibody assay to provide valid and complete differentiation information. Moreover, whereas ELISA 1 had 10-20% false positive results to epitope D for PRCV-infected pigs (set A samples), no false-positive results to epitope D occurred using ELISA 2, indicating its greater specificity. The progression of seroresponses to the TGEV S protein epitopes A or D, as measured by the 2 ELISAs, was similar for both sets (A and B) of samples. Differentiation between TGEV and PRCV antibodies (based on seroresponses to epitope D) was consistently measured after the third week of inoculation.

Animals↗
PubMed2003

West Nile virus encephalomyelitis in horses: 46 cases (2001).

OBJECTIVE: To determine signalment, clinical findings, results of diagnostic testing, outcome, and postmortem findings in horses with West Nile virus (WNV) encephalomyelitis. DESIGN: Retrospective study. ANIMALS: 46 horses with WNV encephalomyelitis. PROCEDURE: Clinical data were extracted from medical records of affected horses. RESULTS: On the basis of clinical signs and results of serologic testing, WNV encephalomyelitis was diagnosed in 46 of 56 horses with CNS signs. Significantly more males than females were affected. Increased rectal temperature, weakness or ataxia, and muscle fasciculations were the most common clinical signs. Paresis was more common than ataxia, although both could be asymmetrical and multifocal. Supportive treatment included anti-inflammatory medications, fluids, antimicrobials, and slinging of recumbent horses. Results of the IgM capture ELISA and the plaque reduction neutralization test provided a diagnosis in 43 horses, and only results of the plaque reduction neutralization test were positive in 3 horses. Mortality rate was 30%, and 71% of recumbent horses were euthanatized. One horse that had received 2 vaccinations for WNV developed the disease and was euthanatized. Follow-up communications with 19 owners revealed that most horses had residual deficits at 1 month after release from the hospital; abnormalities were resolved in all but 2 horses by 12 months after release. CONCLUSIONS AND CLINICAL RELEVANCE: Our findings were similar to those of previous WNV outbreaks in horses but provided additional clinical details from monitored hospitalized horses. Diagnostic testing is essential to diagnosis, treatment is supportive, and recovery rate of discharged ambulatory horses is < 100%.

Animals↗
PubMed1986

Enzyme linked immunosorbent assay used to monitor serum antibodies to bovine respiratory disease viruses.

An enzyme linked immunosorbent assay (ELISA) was applied to the detection of serum antibodies against infectious bovine rhinotracheitis (IBR), parainfluenza-3 (PI3), adenovirus type 3 (adeno 3) and bovine respiratory syncytial (BRS) viruses. Paired serum samples from calves vaccinated with live attenuated virus vaccines were tested. The ELISA compared favorably with the virus neutralization test for detecting serologic responses to IBR, BRS, and adeno 3 viruses or with the hemagglutination inhibition test for PI3 virus. The simplicity, sensitivity and rapidity of the ELISA test makes it a useful tool for immunological studies with respiratory viruses.

Adenoviridae↗
PubMed1993

Evaluation of five hepatitis C virus screening tests and two supplemental assays: performance when testing sera from sexually transmitted diseases clinic attendees in the USA.

The performances of five screening tests (recombinant peptide-based first and second generation tests from Abbott and Ortho, and a synthetic peptide-based test from Biochem Immunosystems) and two supplemental tests: recombinant peptide- based, Abbott neutralization test and Chiron second generation recombinant immunoblot assay (RIBA 2), were evaluated for their ability to detect hepatitis C virus (HCV) antibodies in a population of 276 individuals attending a sexually transmitted diseases (STD) clinic in the USA. Although the five screening tests produced a variable number (35-62) of repeatedly reactive samples, only 13% (36/276) were classified as true positives by the supplemental tests. Thirty-four of the 36 were reactive by all screening tests and 32 of the true positives were reactive by both supplemental tests, while 2 did not neutralize but were reactive in the RIBA 2 test. Of the remaining 2 of the true positives which were discordant by several of the screening assays, 1 was confirmed by both supplemental assays but the other required a chemiluminescent enhancement technique to show positivity in RIBA 2. The sensitivities of the first and second generation Abbott and Ortho tests ranged from 97% to 100% and that of the Biochem test was 94%. The specificities of these tests ranged from 89.2% to 99.6%. The second generation Ortho test presented 9.4% (26/276) false positives. The use of second generation Ortho as a screening test would lead to an excessive number of confirmatory false positives. the positive predictive values of the screening tests ranged from 58.1% to 97.1%. Although the synthetic peptide based Biochem test exhibited the best overall indices, the presence of 2 false negative results would prevent its use as a singular screening test. Nevertheless its high specificity may lend itself to be used as a second screening test before confirmatory testing with RIBA 2.

Journal Article↗
PubMed1980

Characterization of a new potent heparin. 2nd communication: Chemical analysis of the carbohydrate content and determination of the biological activity of a new potent heparin preparation in vitro, using protamine neutralization and amidolytic methods for factor Xa and thrombin.

A new potent heparin preparation was further characterized for carbohydrate content and for biological activities in vitro using the protamine neutralization test and amidolytic methods for factor Xa and thrombin. The chemical analysis of the heparin preparations showed similar amounts of glucosamine and glucuronic acid as known for other heparin preparations. In protamine neutralization test the new heparin was 1.32 times more active than commercial heparin. The amidolytic method using chromogenic substrates S-2222 for factor Xa and S-2238 for thrombin demonstrated that the new heparin was also at least two times more effective than commercial heparin in increasing the rate of inactivation of these serin proteases through antithrombin III.

Animals↗
PubMed1972

Studies on monkeypox virus.

The growth characteristics, including ceiling temperatures for growth, of three strains of monkeypox virus were studied on chick chorioallantoic membrane, growth and plaque formation were studied in RK13 cells, and growth was studied in rabbit dermis. The three strains could not be distinguished by these tests but could be differentiated from variola, vaccinia, and cowpox viruses. Haemagglutination-inhibition tests with homologous and heterologous antisera also showed that the monkeypox strains were indistinguishable, although they could be differentiated from vaccinia and cowpox, but not from variola, viruses. Similar results were obtained in neutralization tests. It is suggested that the monkeypox strains constitute a homogeneous poxvirus entity. The strains can be differentiated from other poxviruses by their cultural characteristics but serologically they are more closely related to variola than to vaccinia or cowpox viruses.

Animals↗
PubMed1976

The detection of transmissible gastroenteritis viral antibodies by immunodiffusion.

Precipitating antibodies against transmissible gastroenteritis viral antigens were detected by the immunodiffusion test in two transmissible gastroenteritis viral hyperimmune antisera and in antiserum prepared against haemagglutinating encephalomyelitis virus but not in sera from several species of normal animals, in antisera prepared against a variety of othet viruses and bacteria or sera from swine with bacterial enteritis. When the immunodiffusion test was compared with the virus neutralization test for the detection of transmissible gastroeneritis viral antibodies in 20 swine sera certain samples which contained high titres of virus neutralizing antibodies failed to produce precipitation while other sera were positive in the immunodiffusion test although their virus neutralizing antibody titres were relatively low. Precipitating antibodies were also detected by immunodiffusion in several samples of milk whey from a sow which had been vaccinated with inactivated transmissible gastroenteritis virus.

Animals↗
PubMed1983

Inducement of cytopathic changes and plaque formation by porcine haemagglutinating encephalomyelitis virus.

ESK cells were shown to be a good medium for propagating the 67N strain of porcine haemagglutinating encephalomyelitis virus, although no cytopathic effect was observed. The virus induced a readily recognizable cytopathic effect in ESK cells, when a noncytotoxic amount of diethylaminoethyl-dextran (DEAE-dextran) was incorporated in the culture medium. Based on this finding, a sensitive, practical assay method for the virus was developed. When DEAE-dextran was incorporated in the agar overlay medium, 67N virus formed plaques in ESK cell monolayers. The cytopathic effect as well as the plaque formation were specifically inhibited by antisera against the virus. Neutralization tests were developed on the basis of these findings. Neutralization and haemagglutination-inhibition tests on swine serum samples indicated a wide dissemination of haemagglutinating encephalomyelitis virus or antigenically-related viruses in Japanese pigs.

Animals↗
PubMed1979

Serological incidence of avian reovirus infection in broiler-breeders and progeny in Nova Scotia.

The plaque neutralization test and the agar gel precipitation test were used to detect neutralizing and precipitating antibody to avian reovirus strain WVU2937 in sera from 14 commercial broiler breeder flocks and eight progeny flocks. Ten breeder flocks (71%) possessed positive agar gel precipitation reactors (598 sera tested) and 12 (86%) possessed plaque neutralization reactors (114 serum pools tested). All broiler flocks possessed agar gel precipitation reactors, but these were not examined for neutralizing antibody. As no avian reovirus vaccine had been used in Canada prior to this survey these reactions were presumably due to natural infection. Clinical evidence suggested that such infection was asymptomatic in most cases. The development and persistence of antibody to reovirus strain WVU2937 was followed in chicks exposed to the virus by oral inoculation or by contact. Neutralizing antibody was demonstrated in all birds by postinoculation day 17 and this persisted for at least six months. Precipitating antibody was also demonstrated in most chicks by postinoculation day 17, but by six months only 12% of the chicks were still agar gel precipitation positive.

Animals↗
PubMed1998

Quantitation of tetanus and diphtheria antitoxins in mouse sera by indirect haemagglutination.

Serum samples obtained from 75 groups of mice immunized with various doses of adsorbed tetanus vaccine, adsorbed diphtheria-tetanus vaccine and adsorbed diphtheria-tetanus-pertussis vaccine were titrated for tetanus antitoxin content by an in-vitro indirect haemagglutination (IHA) and by toxin neutralization test (TN) in mice. From these serum samples of 49 groups of mice which were immunized with combined vaccine containing diphtheria toxoid were titrated for their diphtheria antitoxin content by IHA and by i.d. toxin neutralization test (TN) in guinea pigs. Good correlations were found between the estimates obtained by in-vitro IHA and in vivo TN tests in both tetanus and diphtheria antitoxin titrations. The minimum level of tetanus or diphtheria antitoxin detectable by IHA was 0.00039 IU/ml. It is concluded that IHA is a simple, sensitive and reproducible alternative test which can replace the animal TN tests for the estimation of tetanus and diphtheria antitoxins and could reliably be used in the potency assay of tetanus and diphtheria toxoids of combined vaccines based on antibody induction in mice.

Animals↗
PubMed1999

Infectivity studies of a new baculovirus isolate for the control of the diamondback moth (Plutellidae: Lepidoptera).

This study describes a new baculovirus isolate recovered from infected larvae of the diamondback moth, Plutella xylostella (L.), and identified as a multiple nucleopolyhedrovirus (MNPV). The plaque purified isolate designated as PxMNPVCL3 was found to be pathogenic to P. xylostella, Heliothis virescens (F.), Trichoplusia ni (Hübner), H. subflexa (Guenée), Helicoverpa zea (Boddie), Spodoptera exigua (Hübner), and S. frugiperda (J. E. Smith) larvae in decreasing order of susceptibility. The LC50 for diamondback moth, the most susceptible, was 6 occlusion bodies (OB)/cm2, whereas the most resistant species, namely S. frugiperda, was 577 OB/cm2. PxMNPVCL3 was more pathogenic to diamondback moth by 3-4 log cycles as compared with 2 broad-spectrum baculoviruses, namely Autographa california (alfalfa looper) MNPV and Anagrapha falcifera (celery looper) MNPV. The 3 baculoviruses were compared with each other and characterized by restriction endonuclease (REN) analysis, hybridization, and neutralization tests. Fragmentation profiles generated by REN showed that the 3 baculoviruses shared some fragments in common. Hybridization studies employing digoxigenin labeled PxMNPVCL3 DNA as a probe revealed the close but distinct relationship of these 3 viruses. Neutralization tests confirmed the hybridization studies, namely that the 3 viruses although genetically similar are distinguishable from each other.

Animals↗
PubMed1970

Titration of cholera antitoxin in human sera by microhemagglutination with formalinized erythrocytes.

Microtiter hemagglutination tests employing formalinized sheep erythrocytes sensitized with either crude or purified cholera toxin were used to assay the cholera antitoxin content of human sera. Comparable results were obtained with either crude or purified toxin-sensitized cells with the exception of two sera that gave unusually high hemagglutination titers with the crude toxin. Sera from 13 convalescent cholera patients showed a high degree of correlation between antitoxin levels as determined in vitro by the hemagglutination test and in vivo by the skin permeability factor neutralization test. Fourfold or greater rises in antitoxin levels between acute and convalescent sera were detected in 9 of 15 patients with bacteriologically proven cholera. No significant increases in titer were observed in 14 cases of noncholera diarrhea. Cholera antitoxin was detected by hemagglutination in only 1 of 33 sera, obtained from eight countries, containing vibriocidal antibodies. Formalinized sheep erythrocytes sensitized with toxin and stored at 4 C in the presence of 1:10,000 thimerosal were stable and sensitive for at least 6 months (the longest time tested).

Animals↗
PubMed1986

Dot-enzyme immunoassay for visual detection of antibodies to pseudorabies virus in swine serum.

A modified solid-phase enzyme immunoassay (EIA) is described for the visual detection of anti-pseudorabies virus (anti-PRV) antibody in porcine serum. Dots of PRV antigens were adsorbed to nitrocellulose paper (hence the name dot-EIA), and the remaining nonspecifically reactive sites were blocked with bovine serum albumin or skim milk powder. After immersion in test serum, bound antibodies were reacted with a peroxidase-conjugated anti-porcine immunoglobulin G (H & L). Positive reactions were easily visualized as brown dots after enzyme degradation of a substrate containing hydrogen peroxide and diaminobenzidine. The dot-EIA was comparable to the serum neutralization test and the standard microtiter EIA in its ability to detect antibody in the sera of pigs 9 days after experimental infection and 12 days after contact with infected pigs. The sensitivity and specificity of the dot-EIA relative to the serum neutralization test and the standard EIA were determined from the testing of 856 field sera from the United Kingdom, the United States, and Canada. In all comparisons, both the relative sensitivity and specificity of the dot-EIA were in the order of 98 to 99%. The dot EIA appears to have potential application as a rapid and economical field test in the diagnosis of PRV infection.

Animals↗
PubMed1987

An enzyme-linked immunosorbent assay for detection of flavivirus antibodies in chicken sera.

An enzyme-linked immunosorbent assay (ELISA) was developed to determine the presence of flavivirus antibodies to Murray Valley encephalitis (MVE) and Kunjin viruses in sentinel chicken sera. The development of a quick, reliable assay to detect antibodies to MVE was an essential part of a large-scale surveillance programme to monitor arbovirus activity in Western Australia. This assay was developed for use with alkaline phosphatase conjugated goat anti-mouse IgG using mouse anti-chicken globulin in an intermediate step. There was a significant difference in absorbance values between neutralization test positive and pre-bled sera. However, some sera obtained from sentinel chickens and deemed negative by neutralization demonstrated adsorbance levels above the cutoff level in the ELISA, which reflects the increased sensitivity of this technique. The ELISA test detected antibodies to MVE in chicken sera 7-10 days after infection, whereas these antibodies were only consistently detected by the neutralization test 24 days after infection. Antibodies to both MVE and Kunjin reacted positively with the MVE antigen, but there was little cross-reactivity between this antigen and antibodies to other togaviruses. The main advantages of the ELISA over the neutralization test for detecting antibodies to MVE virus in the sera of sentinel chickens are its greater sensitivity and the speed with which tests can be performed. Results are available within 48 h of receiving specimens and emergency mosquito control measures may then be implemented.

Animals↗