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PubMed1984

Heterogeneity of contagious ecthyma virus isolates.

Results of cross-neutralization tests of 4 isolates of contagious ecthyma (CE) virus and their antisera indicated that the isolates were neutralized to various degrees by the CE virus antisera. Cross-reactions among isolates were unilateral, but not bilateral, and therefore grouping of CE virus isolates by neutralization tests was not possible to obtain. Structural analysis of polypeptides from 11 isolates of CE virus by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the profiles obtained were similar to one another, except for differences observed in the molecular weight region of 37,000 to 44,000. On the basis of these differences, the isolates could be classified into 4 groups. The polypeptides which varied among the different isolates were shown to be in the surface component of the virion and appeared to be components of the surface tubules. Unilateral cross-reactions detected in cross-neutralization tests were found to correlate with the 37,000 to 44,000 dalton polypeptide grouping of the isolates.

Animals↗
PubMed1987

Antigenic variants of Colorado tick fever virus.

Twenty strains of Colorado tick fever (CTF) virus, isolated from ticks, mammals and humans, and two antigenic relatives of CTF virus were compared in cross-neutralization tests. Viruses were tested using single-inoculation sera prepared in hamsters. Antigenic variation, as measured by differences detected in the neutralization test, was noted among the virus isolates identified as strains of CTF virus. The virus strains isolated from humans appeared to vary the most in serological reactions. The two antigenic relatives of CTF virus are clearly distinct from strains of CTF and are different from each other. Antigenic relationships between these two viruses were established using two sets of single-inoculation antisera and both complement fixation and neutralization tests. Six distinct antigenic variants of CTF virus isolated from humans and the virus strain from ticks (75V1906) that showed the least antigenic variation, were tested against 49 coded serum pairs from clinically diagnosed cases of CTF. Significant differences were noted in the number of convalescent-phase sera that reacted with each virus strain and in the number of seroconversions observed with each test virus strain. Convalescent phase sera that reacted with multiple virus strains often varied significantly in antibody titre from one virus strain to another. This indicates that, in some instances, antibody was probably produced in response to infection by different antigenic variants of CTF virus.

Animals↗
PubMed1976

Antigenicity of converting phages obtained from Clostridium botulinum types C and D.

Phage conversion of toxigenicity in Clostridium botulinum types C and D was accomplished by using nontoxigenic strains and phages purified from plaques. Although the morphology of the converting phages seemed to be the same, they were divided into three groups on the basis of their conversion spectrum. The first group consists of phages obtained from toxogenic strains C-Stockholm and C-468. The second group consists of phages from strains D-1873 and C-203. The third group consists of phages from strains D-South African and D-4947. These converting phages were also classified into the same three groups by a neutralization test with specific antiphage sera. Cross-neutralization, however, was observed between phages belonging to group 1 and group 2,by both the neutralization test of converting ability and by a plaque experiment in which the surviving rates of phages were calculated after treatment with each antiphage serum. The antigenic differences among these converting phages should probably comprise one of the reasons for the existence of the specific infection spectrum in C. botulinum types C and D.

Antigens, Viral↗
PubMed1986

Comparative pathogenicity and antigenic cross-reactivity of Rift Valley fever and other African phleboviruses in sheep.

Homologous and heterologous haemagglutination-inhibition (HAI), complement-fixation (CF), immunodiffusion (ID) and mouse neutralization tests were performed with the Lunyo (LUN) and a Zimbabwean strain of Rift Valley fever (RVF) virus, the prototype and a South African strain of Arumowot (AMT) virus and prototype strains of Gordil (GOR), Saint-Floris (SAF) and Gabek Forest (GF) viruses, using immune mouse ascitic fluids prepared against these viruses. Reactions of identity occurred in all tests between LUN and the Zimbabwean strains of RVF and between the two strains of AMT virus. Otherwise, cross-reactions occurred between all the phleboviruses in HAI tests, while reactions in CF, ID and neutralization tests were monospecific for virus serotypes, except that weak cross-reaction occurred between GOR and SAF viruses in CF and ID tests. Four sheep infected subcutaneously with the Zimbabwean strain of RVF virus developed transient fever, viraemia, leucopaenia, relative thrombocytopaenia, haemoconcentration and raised serum enzyme levels, which indicated that the sheep had developed necrotic hepatitis. Disseminated focal necrotic hepatitis was confirmed in a sheep killed for examination on day 4 post-infection. The other three sheep recovered uneventfully after only mild depression and anorexia. Groups of three sheep infected with SAF, GOR, AMT and GF viruses had no demonstrable viraemia or other sign of infection or illness, except that the sheep infected with AMT developed mild fever lasting less than 24 h. Antibody responses were monitored at intervals over a period of 24 weeks in all sheep by homologous and heterologous HAI, CF and cell culture neutralization (CPENT) tests. Homologous antibody responses were marked in the RVF-infected sheep and their sera cross-reacted strongly in HAI tests with antigens of the other viruses. The sera of the RVF-infected sheep cross-reacted less markedly in CF and CPENT tests. Homologous antibody responses were poor in all the sheep infected with phleboviruses other than RVF, and the cross-reactivity of their sera for RVF antigen or virus was negligible. All sheep were challenged with RVF virus 48 weeks after their initial infection. The sheep which had originally been infected with RVF virus were immune and developed neither fever nor viraemia. All other sheep developed fever, viraemia and antibodies to RVF virus. It was concluded that the African phleboviruses, other than RVF, are unlikely to cause disease in livestock or to induce antibodies which could cause confusion in the diagnosis of RVF.

Animals↗
PubMed1989

Potency assay of antibodies against rabies. A report on a collaborative study.

The relative potencies of a number of rabies immunoglobulin preparations were estimated in an international collaborative study comprising eight laboratories in five countries. Two assay methods were used: a virus neutralization test in mice (MNT) and a virus neutralization test in cell culture (RFFIT). Differences between the results obtained by the two methods, which have been reported, could not be generally corroborated. The results indicate that in some laboratories the MNT cause difficulties and give results different from those obtained by RFFIT. In other laboratories such difficulties are not encountered. The results seem to indicate that the RFFIT is a more reliable method than the MNT.

Analysis of Variance↗
PubMed1996

[Rapid detection and identification of human adenovirus directly from conjunctival scrapings by polymerase chain reaction and restriction fragment length polymorphism analysis].

Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis were combined for detection and identification of adenovirus (Ad), a common agent of conjunctivitis in Japan. Nested-PCR with two primer sets that hybridize to the conserved region for hexon protein of 14 prototypes of Ad serotype 1 to 8, 11, 14, 19, 37, 40, and 41, amplified 956 bps DNA fragment. The amplified fragments from 14 prototypes were completely differentiated with the combination of three restriction endonucleases, Eco T14I, Hae III, and Hin fI. We applied this new method to 70 conjunctival scrapings from patients with conjunctivitis, and compared the results with those of the combination of culture isolation and neutralization test. PCR was positive in 38 out of 70 samples (54.3%), whereas 33 of 70 samples (47.1%) were positive by cell culture. Compared with cell culture isolation, the PCR method had a sensitivity of 100% (33 of 33). Positive PCR samples were further classified into Ad 37 (44.7%), 3 (39.5%), 11 (7.9%), 8 (5.3%), and 4 (2.6%) by PCR-RFLP analysis. Of five samples that were PCR positive and cell culture negative, three samples were Ad 37 and two were Ad 8 by PCR-RFLP analysis. These differentiations of cell culture positive samples were identical to the results of the neutralization test. It took only about three days to detect and identify Ad by PCR-RFLP analysis, whereas it took at least two weeks by culture isolation and neutralization test. Our newly developed method of detecting and typing human Ad by PCR-RFLP analysis is more sensitive, accurate, and prompt than the conventional cell culture isolation and neutralization test.

Adenovirus Infections, Human↗
PubMed1989

Antigenic diversity of bovine viral diarrhea-mucosal disease (BVD-MD) viruses recently isolated from persistently infected cattle and mucosal disease, and serologic survey on bovine sera using antigenically different BVD-MD viruses.

Twenty nine recent isolates of bovine viral diarrhea-mucosal disease (BVD-MD) virus, 17 from persistently infected cattle and 12 from mucosal disease, were compared antigenically with the reference strains by a serum neutralization test. The reference viruses were divided into 2 groups, tentatively designated as N and K, based on the antigenic relationships in the cross-neutralization test. Antigenic properties of recent isolates were considerably different with the sources of virus isolation. Seventeen isolates recovered from persistently infected cattle were divided into 3 groups in the neutralization test using antisera to the reference strains; 12 and 2 were considered as the possible members of groups K and N, respectively, and the others belonged to neither group. On the other hand, 10 of 12 isolates recovered from mucosal disease were considered as the possible members of group N, and the others were classified into neither group. Interestingly, none of BVD-MD viruses isolated from cases of mucosal disease belonged to group K. The results of serologic survey on sera collected from 713 cattle at the Hokkaido provinces in 1974 to 1988 indicated that infections of cattle with BVD-MD viruses other than group K were prominent before 1981. Cattle infected with group K BVD-MD virus were first detected in 1982, and increased in number thereafter. The results obtained in this study suggested that BVD-MD viruses with various antigenic properties spread widely among cattle herds, and also a possibility that clinical manifestations in cattle infected with BVD-MD viruses may differ with their antigenic properties.

Animals↗
PubMed1990

Identification of operationally overlapping and independent cross-reactive neutralization regions on human rotavirus VP4.

Cross-reactive neutralization epitopes on VP4 of human rotavirus (HRV) were analyzed by the use of VP4-specific neutralizing monoclonal antibodies (N-MAbs) and MAb-resistant mutants. Seven anti-VP4 N-MAbs obtained in this study by using HRV serotypes 1 and 3 as immunizing antigens showed a variety of cross-reactivity patterns to 20 HRV strains with different serotype specificity in neutralization tests and a broader cross-reactivity to them was found for four N-MAbs in an enzyme-linked immunosorbent assay. On the basis of the reactivity patterns against rotaviruses in neutralization tests, these seven N-MAbs were classified into four groups. Cross-neutralization tests using a total of 12 pairs of MAbs and resistant mutants, including five pairs which had been prepared previously, showed that VP4 of HRV (strain KU) contained two independent antigenic regions. One, region C1, was recognized by a single MAb (YO-2C2) and the other was made up of two antigenic regions (C2 and C3) which overlapped operationally. Identification of amino acid substitution sites on VP4 of representative mutants of HRV strain KU indicated that amino acid positions 385 or 392 and 428 or 433 were critical for the C2 and C3 regions, respectively. These results suggested that regions C2 and C3 exist as conformational antigenic sites.

Animals↗
PubMed1989

Cross-neutralization of genetic reassortants of bluetongue virus serotypes 20 and 21.

Genetic reassortment studies of bluetongue virus (BTV) Types 20 and 21 have revealed a reassortant genotype that was not neutralized serotype-specifically. In reciprocal neutralization tests, BTV 20 and 21 were neutralized specifically by homologous antiserum. Similarly, reassortants that possessed both outer capsid proteins (i.e., VP2 and VP5) from the same parent virus reacted with that antiserum specifically. However, two reassortants, 16(9) and 19(1), with VP2 of BTV 20 and VP5 of BTV 21 had intermediate neutralization characteristics. These reassortants were neutralized to high titres by antiserum to BTV 20 and to lower, but significant titres by antiserum to BTV 21. In addition, antiserum to BTV 20 induced 10-16-fold higher titres in plaque reduction neutralization (PRN) tests with these two reassortants compared with BTV 20 itself. Evidence of the serological cross-reactivity of Reassortants 16(9) and 19(1) was also found with respect to reductions in plaque sizes observed in the PRN tests. The average plaque sizes of these reassortants were reduced to differing extents by antiserum to BTV 20 and 21, while those formed by the parent viruses were reduced in size by homologous antiserum only. Immunoblotting analysis of the structural proteins of BTV 20 and 21 demonstrated that VP2 alone was antigenically distinct, therefore confirming its role in determining serotype specificity in virus-neutralization tests. Electrophoretic analysis revealed considerable migrational differences between VP2 and VP5 of the parent viruses, suggesting that there was some divergence in their molecular weights, intrinsic charges or structural compositions. Taken together, the data suggest that the intermediate neutralization characteristics of the reassortants that contain VP2 and VP5 from different parent viruses are due to conformational alterations in their outer capsid structure which allow antibody recognition of common neutralizing epitopes that are not exposed on BTV 20 or BTV 21.

Antibodies, Viral↗
PubMedDate not supplied

[A serological survey of arboviruses in the human population of Senegal].

2,457 serum samples collected during an epidemiological survey on treponematosis in Senegal by the W. H. O. IR051 team in five areas of Senegal between 1972 and 1975 were studied for arbovirus antibodies using hemagglutination inhibition test. In addition 998 were studied using CF test and 1012 in neutralization test with yellow fever virus. The prevalence of arbovirus antibodies is important in all the country and does not vary basically between the different areas. In group A, chikungunya antibody is the most frequent and Sindbis antibody was found only in areas where migrant birds are resting. There is evidence of recent yellow fever infection in Upper Casamance and in Eastern Senegal. Most of the children are not immune and have to be immunized. Zika and Wesselsbron viruses show activity in all the areas and West-Nile, as Sindbis, is related to areas where birds are numerous. Bunyamwera virus activity is low.

Adult↗
PubMed1988

Enzyme-linked immunosorbent assay for the detection of antibodies to the alcelaphine herpesvirus of malignant catarrhal fever in exotic ruminants.

An ELISA for antibodies to the alcelaphine herpesvirus-1 of malignant catarrhal fever was developed. Of sera that represented 42 exotic ruminant species, 216 were evaluated by the ELISA and a virus-neutralization test. A significant correlation (r = 0.564, P less than 0.001, n = 216) between the ELISA and virus-neutralization test results was found. Of the sera having positive test results by virus neutralization, 86.1% also had positive results by the ELISA, and of the sera having negative test results by virus neutralization, 83.9% also had negative results by the ELISA. The presence of antibody, as measured by the ELISA, correlated with clinical signs of malignant catarrhal fever and the isolation of herpesvirus.

Animals↗
PubMed1989

An international collaborative study of an anti-infectious bursal disease virus reference serum.

Fourteen laboratories participated in a collaborative study of a freeze-dried preparation of anti-infectious bursal disease virus serum to assess the suitability of the serum as a standard for use in the infectious bursal disease virus neutralization test. Ten laboratories carried out micro-virus neutralization tests and six carried out plaque reduction tests, two laboratories carrying out both tests. When titres were expressed as a proportion of that obtained for a reference preparation there was a marked reduction in variation between results from different laboratories. The use of a reference preparation was therefore of value when comparing results from different laboratories. It is proposed that the reference preparation used in this study be used as a standard to facilitate the comparison of results from different laboratories. The proposed standard contains by definition 10,000 UK units.

Animals↗
PubMed1993

[Serological diagnosis of adenovirus conjunctivitis].

We compared the serum antibody titers against adenoviruses of pair sera and the identification of isolated adenovirus from 17 patients with acute conjunctivitis. Isolated adenoviruses were Ad3 in ten cases, Ad8 in four cases, Ad37 in two cases, and Ad4 in one case. Among these cases, eleven cases showed identical results in a neutralization test. In one patient from whom Ad3 was isolated, no neutralizing antibody was found. In 3 patients from whom Ad8 or Ad37 was isolated, there were discrepancies between serological results of the neutralization test or the haemagglutination inhibition test, and viral isolation. Antibody titers against adenoviruses subgenus D, such as Ad8, 19 and 37 were increased not only for the isolated serotypes, but also for other serotypes of this subgenous.

Adenovirus Infections, Human↗
PubMed1977

Micro-indirect hemagglutination test for detection of antibody against transmissible gastroenteritis virus of pigs.

A micro-indirect hemagglutination (IHA) test was developed for detecting antibody against transmissible gastroenteritis (TGE) virus of pigs. TGE virus propagated in swine kidney cell cultures was highly purified and concentrated by the combination of ammonium sulfate precipitation, treatment with fluorocarbon, and sucrose density gradient centrifugation. Tanned sheep erythrocytes were sensitized with purified virus for use in the IHA test. The results of testing 104 serum samples collected from pigs in the field indicated that the IHA antibody titers were approximately five times higher than those obtained by a serum neutralization test and that there was good correlation between the antibody titers determined by the two tests. High IHA antibody titers developed in pigs experimentally exposed to virulent TGE virus. Sensitized sheep erythrocytes were stable under long-term storage at 4 degrees C (at least for 50 days). The conclusions made are that the IHA test described is more sensitive than the serum neutralization test for the detection of TGE antibody and may be of value for serodiagnosis of TGE.

Animals↗