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PubMed1990

Antigenic variations in bovine viral diarrhea viruses detected by monoclonal antibodies.

Five murine monoclonal antibodies (MAbs) against the NADL strain of bovine viral diarrhea (BVD) virus were developed, identified, and characterized. Four of the MAbs were directed against a 53-kilodalton (kDa) viral protein, and one was specific to a 47-kDa polypeptide. Competitive radioimmunoassay showed that two MAbs were specific to related epitopes of the 53-kDa protein, and the other three MAbs were each specific to a different epitope. The MAbs were used to study heterogeneity among BVD virus strains. Various degrees of reactivity of cytopathic and noncytopathic virus isolates were detected by virus neutralization and immunofluorescence assays. The virus isolates were divided into six groups based on the neutralization test. The results indicated that the 53-kDa glycoprotein of BVD virus is the major protein involved in virus neutralization and that only a few epitopes of the protein contribute to the neutralization. None of the MAbs neutralized all the BVD virus isolates tested in this study, suggesting antigenic variations among BVD virus isolates.

Animals↗
PubMedDate not supplied

Antibody response in cattle after vaccination with inactivated and attenuated rabies vaccines.

Despite the absence of current official reports showing the number of cattle infected by rabies, it is estimated that nearly 30,000 bovines are lost each year in Brazil. In order to minimize the important economic losses, control of the disease is achieved by eliminating bat colonies and by herd vaccination. In this study, we compare the antibody response in cattle elicited by vaccination with an attenuated ERA vaccine (AEvac) and an inactivated-adjuvanted PV (IPVvac) vaccine. The antibody titers were appraised by cell-culture neutralization test and ELISA, and the percentage of seropositivity was ascertained for a period of 180 days. IPVvac elicited complete seropositivity rates from day 30 to day 150, and even on day 180, 87% of the sera showed virus-neutralizing antibody titers (VNA) higher than 0.5IU/ml. There were no significant differences between the VNA titers and seropositivity rates obtained with IPVvac in the two methods tested. AEvac, however, elicited significantly lower titers than those observed in the group receiving inactivated vaccine. In addition, the profiles of antirabies IgG antibodies, evaluated by ELISA, and VNA, appraised by cell-culture neutralization test, were slightly different, when both vaccines were compared.

Animals↗
PubMed1976

Detection of antigenic differences among street and fixed rabies virus strains by the counterimmunoelectrophoresis test.

Using the counterimmunoelectrophoresis test, two street rabies virus strains (Mangosta and Apipe) revealed antigens not detected in the standard challenge virus (CVS). No antigenic differences, however, were found between CVS and another fixed rabies virus strain (strain 91) by this method. The results of serum neutralization tests revealed similar antigenic relationships among the rabies virus strains studied. These findings are discussed in terms of their significance to antigenic variations in rabies virus strains.

Counterimmunoelectrophoresis↗
PubMed1973

Rabies group-specific ribonucleoprotein antigen and a test system for grouping and typing of rhabdoviruses.

Cell-associated ribonucleoprotein (RNP) was isolated from BHK-21 cells infected with several strains of rabies and rabies-related viruses. The RNP-antigen from rabies and related viruses induced the formation of complement-fixing, precipitating, and immunofluorescent antibodies, and proved to be the group-specific antigen common to all rabies viruses. Antigens of the envelope which induce virus-neutralizing antibodies are apparently determinative for the serotype of a virus as evidenced by two-way neutralization tests. A combination of these methods seems to be a useful approach to the serological grouping and typing of rhabdoviruses.

Animals↗
PubMed1988

A continuous bovine kidney cell line for routine assays of foot-and-mouth disease virus.

A continuous bovine kidney cell line, LF-BK, arose from primary bovine calf kidney cells that survived infection with a temperature-sensitive mutant of foot-and-mouth disease virus. No virus was recovered after the first passage. Cells of Passage 48 were inoculated into two steers which remained healthy and did not develop neutralizing antibodies to the virus. The karyotype of cells of the 53rd and 87th passages was similar and revealed that the cells were markedly transformed. The modal number of diploid chromosomes was 52 at both passage levels. LF-BK cells and primary bovine kidney cells were equally susceptible in plaque assays to each of the 7 types of foot-and-mouth disease virus. The cell line and primary bovine kidney cells were less susceptible than primary bovine thyroid cells to several subtypes of the virus in suspensions of tongue epithelium. The LF-BK continuous cell line is recommended for routine plaque assays or plaque neutralization tests as a substitute for primary bovine kidney cells.

Animals↗
PubMed1984

Immunoglobulin M antibody capture enzyme-linked immunosorbent assay for diagnosis of St. Louis encephalitis.

Sera from patients with St. Louis encephalitis were tested with an immunoglobulin M (IgM) antibody capture enzyme immunoassay (MAC ELISA). The assay used five reagents: antihuman IgM, test serum, sucrose-acetone-extracted mouse brain antigen, broadly cross-reactive flavivirus monoclonal antibody conjugated to alkaline phosphatase, and substrate (p-nitrophenyl phosphate). MAC ELISA endpoint titers correlated (r = 0.893) with the absorbance value of a 1:100 dilution of patient serum. Significant (fourfold or greater) changes in the endpoint titers between paired sera corresponded to a critical ratio (ratio of absorbance values at the 1:100 dilution) of greater than or equal to 1.3. IgM antibodies were detected in 71% of patients bled at 0 to 3 days after the onset of illness, in 99% bled at 4 to 21 days, and in 91% bled at 22 to 67 days. Thereafter, the IgM seropositivity rate declined; however, 29% of sera were still positive at 115 to 251 days after the onset of illness. MAC ELISA titers were significantly correlated with hemagglutination inhibition (r = 0.258) and neutralization (r = 0.711) titers. Because IgM antibodies appeared early and waned rapidly, a diagnosis was made on the basis of a decrease in titer more often by MAC ELISA than by hemagglutination inhibition, complement fixation, or neutralization tests. IgM antibodies generally showed a high degree of specificity; heterologous cross-reactions were, however, present in 4 of 14 sera examined. The MAC ELISA is useful for the rapid, early diagnosis of St. Louis encephalitis.

Antibodies, Viral↗
PubMedDate not supplied

[The evaluation of a commercial EIA test system for determining the specific activity of antiherpetic preparations].

The data on the use of a commercial EIA test system for detection of antibodies in control of preparations against herpes simplex and cytomegaloviruses are presented. The enzyme immunoassay test system for antibody determinations to herpes simplex virus produced by the Odessa bacterial preparations enterprise was shown to be suitable for determination of the specific potency (antigenicity) of herpes simplex vaccine. The advantages of this method over the currently used neutralization test were established. Titration of commercial immunoglobulins detects lots with high litres of antibody to herpes simplex virus. For the same purpose, lots of commercial immunoglobulins were tested for antibodies to cytomegalovirus using a West Germany test-system (Behring). It is concluded that enzyme immunoassay test systems for antibody determinations may be used for screening of lots of immunoglobulins of special effects (against herpes simplex and cytomegalovirus infections) both at the stage of serum and final preparation screening.

Animals↗
PubMed1978

Location of type-specific antigens in calf rotaviruses.

Rotavirus antisera with and without neutralizing activity to calf rotavirus were compared for their ability to agglutinate calf rotavirus particles with and without an outer capsid layer. Particles without the outer capsid layer were agglutinated by antisera with immunofluorescent antibody activity and by antisera with immunofluorescent antibody and neutralizing activity. Particles with the outer capsid layer were agglutinated only by antisera with neutralizing activity. The neutralization test appears to be type specific, and it was concluded that type-specific antigens are associated with the outer capsid layer of rotaviruses. Since particles with the outer capsid layer were not agglutinated by antisera lacking neutralizing activity but possessing immunofluorescent antibody activity, it was concluded that in intact particles the group-specific antigen is masked by the outer capsid layer.

Animals↗
PubMed1985

Localization of a neutralization site of Theiler's murine encephalomyelitis viruses.

Theiler's murine encephalomyelitis viruses (TMEV) are picornaviruses that produce enteric and neurological diseases in mice. Subgroup TO strains of TMEV cause persistent infections with demyelination, while subgroup GDVII strains neither persist nor demyelinate. We produced neutralizing monoclonal antibodies (mAbs) to clarify the mechanisms of persistence and demyelination. Some of the neutralizing mAbs reacted with isolated VP1 on Western blots, while others were conformation specific. The neutralization site for the former TMEV mAbs was on the VP1 trypsin cleavage site of the intact virion. The neutralization site for the conformation-specific mAbs was distinct and was not affected by trypsin. Trypsin treatment of subgroup TO strains increased their infectivity for L cells, whereas the infectivity of subgroup GDVII strains was decreased by trypsin treatment. Subpopulations of virus in subgroup TO-infected tissue culture cells and in infected mouse brain homogenates contained VP1-cleaved virus; this VP1-cleaved virus gave rise to a large persistent fraction in neutralization tests when it was reacted with VP1-specific mAbs. These findings have implications regarding the pathogenesis of subgroup TO demyelinating disease. TMEV VP1 cleavage may be important for virus persistence because of disruption of a major neutralization epitope. The change in virus surface structure caused by VP1 cleavage may affect cell binding and lead to altered cytotropism. Immunocytes, which have been implicated in subgroup TO demyelination, may provide a source for proteases for VP1 cleavage.

Animals↗
PubMed2003

UNA virus: first report of human infection in Argentina.

Una virus (UNAV), Togaviridae family, is widely distributed in South America, where infections have been detected in mosquitoes and vertebrate hosts (humans, birds and horses). We analyzed human sera from Córdoba inhabitants aged 44 to 89 years and using a neutralization test, we found a prevalence of UNAV antibodies of 3.8% (3/79). The low titers detected suggest past infections probably acquired in rural areas of the Province of Córdoba (central Argentina). None sera were found positive for MAYV neutralizing antibodies. This is the first report of human infections by UNAV in Argentina.

Adult↗
PubMed1973

Lyophilized combination pools of enterovirus equine antisera: preparation and test procedures for the identification of field strains of 42 enteroviruses.

This paper describes the preparation of 8 dried pools (designated A to H) of sera. Each pool is composed of 10 or 11 of 42 individual enterovirus equine sera and contains 500 antibody units of each serum component per 0.1 ml. Procedures for using the antiserum pools are given, and guidance is provided for interpreting the results of serum neutralization tests in identifying field isolates.

Animals↗
PubMed1997

Genomic (5'UTR) and serological differences among German BVDV field isolates.

Isolates of bovine viral diarrhoea virus (BVDV) collected in Germany were examined for their genomic heterogeneity in sequences from the 5'untranslated region (UTR) of the viral genome. Polymerase chain reaction (PCR) tests based on the 5'UTR and the region coding for the NS2-3/4A polypeptide were used to differentiate between BVDV I and BVDV II genotypes. Eleven out of 96 BVDV-isolates were identified as BVDV II. Virus neutralization tests with BVDV I- or II-specific antisera raised in cattle were done. The mean titers were reduced by 7.2-fold (BVDV I-antiserum versus type II-isolates) or 35-fold (BVDV II-antiserum versus type I-isolates) when using the respective heterologous virus.

Animals↗
PubMed1992

Characterization of a major neutralization domain of Ross river virus using anti-viral and anti-peptide antibodies.

The E2 glycoprotein of the alphavirus Ross River virus (RRV) contains three defined neutralization epitopes (a, b1 and b2) with determinants located between amino acids 216 and 251 in the linear sequence (Vrati et al., 1988, Virology 162, 346-353). The antigenic structure of this region has been examined using hyperimmune mouse antiserum against RRV and antiserum against four synthetic peptides representing linear amino acid sequences in the neutralization region of E2. In plaque reduction neutralization tests using hyperimmune antiserum to RRV, an RRV mutant altered at all three neutralization epitopes was markedly more resistant than the parental virus; variants altered at single epitopes could not be distinguished in these tests. Sera from mice immunized with synthetic RRV E2 peptides conjugated to keyhole limpet haemocyanin reacted, in a direct ELISA, with the specific region of RRV represented by the peptide. The same sera did not neutralize or immunoprecipitate RRV in solution or bind to RRV in a capture ELISA. The RRV peptides did not prime mice to react to a subimmunogenic dose of RRV; they did not bind monoclonal or polyclonal antibodies to RRV. We conclude that a significant proportion of the neutralizing antibody response in mice is elicited by epitopes a, b1, and b2 of RRV E2 and that the sites to which neutralizing antibodies bind are formed by complex folding.

Animals↗
PubMedDate not supplied

[The interaction of monoclonal antibodies to the structural proteins of the Vnukovo-32 vaccinal virus with other viruses of the rabies group].

The interaction of 7 monoclonal antibodies (MCA) to the nucleocapsid complex and 3 MCA to protein G of the vaccine virus Vnukovo-32 with 33 and 27 members of the rabies virus group, respectively, was studied. The indirect immunofluorescence test showed 7 MCA to the nucleocapsid complex to recognize 4 antigenic determinants (AD). Two MCA recognized the AD common for all the viruses under study. Individual ecological variants may be detected using other MCA. Three MCA to protein G had marked virus-neutralizing activity. MCA 1C5 neutralized all the rabies viruses under study. The other two MCA differed in the number of viruses they could neutralize. The viruses under study were divided into 4 groups depending on their interactions with certain MCA in neutralization test.

Animals↗
PubMed1988

Malpais spring virus: a new vesiculovirus from mosquitoes collected in New Mexico and evidence of infected indigenous and exotic ungulates.

Two virus isolates, 1 each from Aedes campestris and Psorophora signipennis mosquitoes collected in south central New Mexico in August 1985, were shown by neutralization tests to be identical to each other, but not to any of more than 250 arthropod-borne and other viruses. Electron microscopy of 1 isolate (85-488NM, chosen as the prototype) indicated that this strain shares morphologic characteristics with viruses of the family Rhabdoviridae. Indirect fluorescent antibody tests indicated that this virus is a member of the genus Vesiculovirus, but is not closely related to any of the North American or other rhabdoviruses with which it was tested, including vesicular stomatitis (Indiana) and vesicular stomatitis (New Jersey) viruses. The name Malpais Spring virus is proposed for this newly recognized vesiculovirus. A serologic survey indicated that Malpais Spring virus infects indigenous (mule deer and pronghorn) and exotic (gemsbok) ungulates at and near the sites where the mosquitoes from which the virus strains were isolated were collected. Antibody prevalence in wild animals indicates that the pronghorn and gemsbok may play roles as hosts for Malpais Spring, epizootic hemorrhagic disease (New Jersey), and bluetongue viruses in this area.

Aedes↗
PubMedDate not supplied

[Neutralization of Venezuelan equine encephalomyelitis virus by anticellular serums].

The results of the study of host antigens in Venezuelan equine encephalomyelitis virus by means of neutralization test in tissue culture using sera containing antibody for the species-specific antigens, Forssman antigen and group A and B antigens are presented. They show the inhibiting effect of the sera to be not uniform. The greatest neutralizing effect on the virus was exerted by immune sera to chick embryo fibroblasts and their fractions (by 0.5-3.9 lg PFU/ML). The lack of the virus neutralizing effect in sera for the Forssman antigen and for group A antigen appears to depend upon their deeper localization in the structure of virion.

Animals↗
PubMed1977

Infectious hepatitis (hepatitis A) research in nonhuman primates.

A satisfactory animal model has been found for laboratory studies of human hepatitis A-namely, the white-moustached marmoset (Saguinus mystax). With this species it has been possible to perform serum-neutralization tests and to develop immune-adherence and complement-fixation tests demonstrating antigen and antibody to the virus. The recent work in marmosets has also led to determination of the agent's characteristics: it most closely resembles the enteroviruses of the picornavirus family. These advances open the way for development of a routine serologic test for diagnosis of the disease, of a human immune globulin for general use that would be precisely standardized for hepatitis A antibody, and, ultimately, of a vaccine. They also provide bases for epidemiologic studies that could reveal nonspecific measures for the disease's control. In addition, there is indication that marmosets could be used for safety control of the hepatitis B vaccine that has already been developed. An adequate supply of S. mystax-threatened by recent embargoes on their exportation-is essential to continuation of this work. The question of marmoset supply, both in the short term and over the long range, deserves serious review.

Animals↗