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PubMedDate not supplied

[A common antigenic epitope in influenza A virus (H1, H2, H5, H6) hemagglutinin].

Avian influenza A viruses belonging to hemagglutinin (HA) subtypes H5 and H6 were studied in the infectivity neutralization test and radioimmunoprecipitation assay (RIPA) with monoclonal antibody MAb C179. This MAb recognizes a conformational antigenic epitope in the stem region of HA formed by two regions (amino acid positions 318-322 in HA1 subunit and 47-58 in HA2), conserved in all H1 and H2 influenza viruses. MAb C179 reacts with HA of H5 viruses in RIPA and neutralizes these strains as efficiently as H2 viruses. C179 precipitates H6 subtype HA but does not neutralize the infectivity of these viruses. Comparison of amino acid sequences of H2, H5, and H6 strains showed identical epitope recognized by MAb C179 in H5 and H6 HAs, which differs from epitopes of H1 and H2 by two amino acids in the HA2 subunit. Causes of disagreement between immunoprecipitation of H6 HA by MAb C179 and neutralization of this serosubtype by this MAb are discussed.

Animals↗
PubMed1976

Identification of paramyxovirus-specific haemolysis-inhibiting antibodies separate from haemagglutinating-inhibiting and neuraminidase-inhibiting antibodies. 1. Sendai virus haemolysis-inhibiting antibodies.

Egg-grown Sendai virus was used for preparation of rabbit hyperimmune sera directed against purified whole virus and pronasetreated projectionless virus particles. These sera and convalescent sera after natural Sendai infection in guinea pigs were studied in haemolysis-inhibition (HLI), haemagglutination-inhibition (HI) and neuraminidase-inhibition (NI) tests both before and after absorption with Tween 80-ether (TE) treated virus preparations. In addition, neutralization tests using the different sera were carried out. HI and NI antibodies and the major population of neutralizing antibodies in convalescent sera were removed by absorption with TE treated virus material without changing the titre of non-HI HLI antibodies. Rabbit hyperimmune sera directed against projectionless virus particles exhibited HLI antibody titres in marked excess of HI and NI antibody titres, whereas this was not found in sera against purified whole virus. In contrast, absorption of sera against projectionless particles eliminated HI antibodies without changing the titre of non-HI HLI antibodies. The protein composition of antigenic preparations used in absorption experiments and for preparation of sera was investigated by SDS-polyacryladmie-gel electrophoresis. TH treatment had no significant effect on the polypeptide pattern of Sendai virus. Pronase-treatment predominantly affected the two glycosylated proteins of Sendai virus. The larger glycoprotein was not detectable in pronasetreated projectionless virus particles, whereas the smaller glycoprotein was present in reduced quantities.

Animals↗
PubMed1990

Presence of three P types (VP4 serotypes) and two G types (VP7 serotypes) among bovine rotavirus strains.

Cross neutralization tests with a panel of rotavirus strains representing previously described nine VP7 (G) serotypes revealed that bovine rotavirus strain KK-3, a prototype Japanese bovine serotype 2, belonged to a new serotype (G10), confirming and extending the recent report of Snodgrass et al. [J. Clin. Microbiol. 28: 504-507 (1990)] which showed that hyperimmune serum to the KK-3 strain neutralized the B223 strain, a proposed type strain of G10. Further antigenic characteristics of the KK-3 strain, as well as the 0510 strain (a G6 strain isolated in Japan), were examined in terms of their VP4 (P) specificity. For the characterization of P types, we employed genetic reassortants that possess VP4 gene for UK and VP7 gene for D (G1), VP4 gene for NCDV and VP7 gene for SA11 (G3), or VP4 gene for SA11 and VP7 gene for NCDV (G6) in the plaque reduction neutralization assay with hyperimmune sera against these two Japanese strains and the prototype bovine rotavirus NCDV strain. While the 0510 strain had UK-like P and NCDV-like G types, the KK-3 strain had a distinct set of P and G types. Thus, at least three P types (NCDV-, UK-, and KK-3-like) and two G types (G6 and G10) are present among bovine rotavirus strains.

Animals↗
PubMed2001

Bovine ephemeral fever in Taiwan.

Bovine ephemeral fever (BEF) is a vector-borne disease of cattle, spanning tropical and subtropical zones of Asia, Australia, and Africa, caused by Ephemerovirus of the Rhabdoviridae. Taiwan has had 3 BEF epizootics, occurring in 1989, 1996, and 1999, since the vaccination regimen was initiated in 1984, given once a year in the spring with a single-dose formaldehyde-inactivated vaccine using the 1983 isolate as the seed virus. This study evaluated the 1999 population immunity against BEF virus in Taiwanese dairy cows with a neutralization test and whether the recent BEF virus isolates have mutated significantly from the vaccine virus. In March 1999, before vaccination, 94% of the animals studied were already seropositive, suggestive of an endemic or persistent infection from the previous year. By June 1999, when 51% of herds had been vaccinated, the antibody level rose, and by September 1999, the serum-neutralizing antibody (SNA) level fell to a minimum, preceding the outbreak of BEF in October 1999, during which the antibody levels of vaccinated cows continued to decline while those of unvaccinated cows rose sharply. The results suggest that, in 1999, vaccine-induced immunity was partially protective against BEE Because the current single-dose vaccination regimen resulted in minimal population immunity by September, a booster vaccination given in late summer may be advisable for future disease control. Analysis of the glycoprotein gene of Taiwanese isolates between 1983 and 1999 showed a 97.4-99.6% homology, with an alteration of 4 amino acids in antigenic sites G1, G3b, and G3c. Phylogenetic analysis of Taiwanese isolates revealed at least 2 distinct clusters: the 1983-1989 isolates and the 1996-1999 isolates. Both were distinct from 2 Japanese strains and the Australian BB7721 strain. Thus, at least 2 distinct BEF viruses, which had diverged before 1983, existed in Taiwanese dairy cows.

Animals↗
PubMedDate not supplied

[Isolation of immunoglobulins from the egg yolk of hens immunized with intestinal viruses].

Antibodies from the yolk of eggs of chicken immunized with enteric viruses (simian rotavirus SA 11, poliomyelitis virus type 2, and Coxsackie B2) were obtained. The time course of the emergence and amplification of antibody in the yolk was followed for several months by neutralization tests and enzyme immunoassay. The long-term persistence of a high antibody level in the yolk, the simplicity of generation of large amounts of chromatographically pure preparations, as well as specificity of chicken immunoglobulins open ways for their employment in different test systems for the detection and identification of enteric viruses.

Animals↗
PubMed1999

Isolation of thogoto virus (Orthomyxoviridae) from the banded mongoose, Mongos mungo (Herpestidae), in Uganda.

Small wild vertebrates were trapped during an investigation into possible vertebrate reservoirs of o'nyong-nyong (ONN) fever virus in Uganda in 1997. Antibody neutralization test results and virus isolation attempts were negative for ONN virus, confirming the work of earlier investigators, who also failed to find evidence for a nonhuman ONN virus reservoir. In the course of these ONN virus studies, Thogoto virus was isolated from one of eight banded mongooses (Mongos mungo). This is the first isolation of Thogoto virus from a wild vertebrate. Neutralizing antibodies to Thogoto virus were also found in two of the other mongooses.

Animals↗
PubMed2003

Protection of SA14-14-2 live attenuated Japanese encephalitis vaccine against the wild-type JE viruses.

OBJECTIVE: To explore on the immunity of live attenuated Japanese Encephalitis (JE) vaccine (SA14-14-2) to different wild JE virus (JEV) strains. METHODS: The neutralizing effect of the vaccine against different wild JE virus strains was detected by plaque reduction neutralization test (PRNT), and the immunogenicity was studied on mice by vaccination -challenge protection test. In the PRNT, pooled sera from vaccinated human were tested against 10 strains of JEV, one isolated in Taiwan and 9 from other Asian countries. In the vaccination challenge test, mice received one dose of the live vaccine subcutaneously and were challenged intraperitoneally 14 days later against 22 JEV virus strains, 11 were isolated in China and the other 11 from Tailand, Vietnahailam, Indonesia, India, Philippines and Japan. RESULTS: The protection rates to all the 22 challenge virus were 90% - 100% when 340 PFU/0.1 ml vaccinate virus was administered. The neutralizing effect showed that all the JEV isolates many have neutralized by the sera. CONCLUSION: SA14-14-2 live attenuated prepared with strain SA14-14-2 is broadly immunogenic and may have effective protection against in Asian JE affected countries.

Adolescent↗
PubMed1975

Serologic classification of feline caliciviruses by plaque-reduction neutralization and immunodiffusion.

Serologic classification of 14 isolated of feline caliciviruses was carried out, using plaque-reduction neutralization tests. Sixty to 200 plaque-forming units of virus were employed against 20 antibody units of hyperimmune goat antiserums prepared to individual isolates. The results established that these viruses were related in various degrees, but no 2 were identical. Arrangements in order of the greatest intergroup reactions yielded essentially 1 serotype with the exception of 1 virus showing 1-way neutralization reactions with heterologous isolates. The geographic origin, the site of viral isolation, or the plaque size had no relationship with the neutralization pattern. The F-9 isolate that showed the greatest intergroup reactions was proposed as the possible reference virus. The viruses were indistinguishable by using gel-diffusion analysis against cat antiserums.

Animals↗
PubMed1987

Comparison of three serotests for the detection of pseudorabies antibodies in pigs.

The serum-neutralization test (SN), enzyme-linked immunosorbent assay (ELISA) and the radial immunodiffusion enzyme assay (RIDEA) were compared for the detection of pseudorabies (PRV) antibodies in swine sera. A total of 1285 serum samples were tested. All three tests were considered useful in determining the PRV antibody status of swine on a herd basis, but available evidence supports the continued use of SN as the definitive test because of possible false positive reactions associated with ELISA and RIDEA.

Animals↗
PubMed1983

Immunological differences among the cholera/coli family of enterotoxins.

Pure enterotoxins from two strains of Vibrio cholerae and choleragen-related heat-labile enterotoxins (LTs) from strains of Escherichia coli of human and porcine origin were examined by Ouchterlony-type immunodiffusion assays and by neutralization tests in Y-1 adrenal cells using specific and immunopurified antisera. In accordance with previous findings, the results indicated that each of the toxins shared antigens with each of the others and that each, in addition, possessed unique antigenic determinants. The present study, however, indicates further that enterotoxin-type specific antibodies, in some instances, account for a major portion of the neutralizing activity. The full extent and importance of the antigenic drift in the cholera/coli family of ADP-ribosylating, adenylate cyclase-activating, heat-labile enterotoxins remains to be determined. The results will be pertinent to efforts to develop broad-spectrum antitoxic immunity as well as in the development of methods for the rapid detection and identification of enterotoxigenic strains.

Bacterial Toxins↗
PubMed1986

Inhibition of erythropoiesis by human parvovirus-containing serum from a patient with hereditary spherocytosis in aplastic crisis.

Aplastic phase serum from a patient with aplastic crisis of hereditary spherocytosis, which was demonstrated to contain human parvovirus, inhibited in vitro erythroid colony formation almost completely. Human parvovirus was resistant to heating for 30 min at 56 degrees C. The suppressive effect of the serum was completely abrogated by adding convalescent phase serum from another patient with aplastic crisis of hereditary spherocytosis. Some normal sera had similar neutralizing ability. The results suggested that aplastic crisis of a patient with hereditary spherocytosis is caused by human parvovirus and that the neutralizing test could offer a tool for predicting the future occurrence of aplastic crisis in the patients with chronic hemolytic anemia.

Adolescent↗
PubMedDate not supplied

Avian infectious bronchitis: characterization of new isolates from Italy.

The isolation of four new variants or serotypes of avian infectious bronchitis virus in Italy is reported. The antigenic characteristics of these strains were investigated by cross-neutralization tests with the new isolates, Fa 6881/97, AZ 27/98, AZ 20/97, and BS 216/01; two of the most common European serotypes, AZ 23/74 and CR 88121 (793B); and the classic Massachusetts M41 serotype in association with a panel of 17 specific antisera. On the basis of the results obtained, the new isolates show relevant serologic differences. In fact, the four isolates were not neutralized by antisera against the most common European and American serotypes; the AZ 20/97 isolate was partially neutralized by FA 6881/97 antiserum but not reciprocally. The closely related Fa 6881/97 and AZ 27/98 isolates can be considered rather diffused in our country because they have been isolated over 20 times in the last 3 yr in different parts of Italy. On the contrary, the AZ 20/97 and BS 216/01 isolates were reported only once so far. The reverse transcription-polymerase chain reaction showed that Fa 6881/97 isolate is related to 793B isolate, whereas AZ 27/98 and BS 216/01 isolates appeared not to be related to the most common European and Massachusetts serotypes.

Animals↗
PubMed2001

Experimental infections of pigs with Japanese encephalitis virus and closely related Australian flaviviruses.

The flavivirus Japanese encephalitis (JE) virus has recently emerged in the Australasian region. To investigate the involvement of infections with related enzootic flaviviruses, namely Murray Valley encephalitis (MVE) virus and Kunjin (KUN) virus, on immunity of pigs to JE virus and to provide a basis for interpretation of serologic data, experimental infections were conducted with combinations of these viruses. Antibody responses to primary and secondary infections were evaluated using panels of monoclonal antibody-based blocking enzyme-linked immunosorbent assays and microtiter serum neutralization tests (mSNTs). Identification of the primary infecting virus was possible only using the mSNTs. Following challenge, unequivocal diagnosis was impossible due to variation in immune responses between animals and broadened and/or anamnestic responses. Viremia for JE virus was readily detected in pigs following primary infection, but was not detected following prior exposure to MVE or KUN viruses. Boosted levels of existing cross-neutralizing antibodies to JE virus suggested a role for this response in suppressing JE viremia.

Animals↗
PubMed1980

Pre-exposure prophylaxis of humans against rabies: I. Studies on personnel at the Burma Pharmaceutical Industry.

This is the first time in Burma where personnel at risk against rabies have been pre-immunized and the effectiveness of such a procedure has been studied for nearly two years. The first batch of lyophilized, Semple-type, beta propiolactone inactivated anti rabies vaccine produced by the Burma Pharmaceutical Industry (B.P.I.) was used to immunize 55 B.P.I. workers previously unexposed to rabies and with no history of rabies vaccination. Three doses of 0.25 ml of the vaccine were given intradermally at one week intervals. Booster doses were given on the 98th, 392nd and 592nd day after the first dose. Blood samples were taken and serum neutralization tests were performed at varying time intervals after basic immunization and booster doses. Satisfactory antibody responses were obtained. The course of immunological response is presented and discussed.

Adult↗
PubMed1995

[Epidemiology of infectious hematopoietic necrosis (IHN) of salmonid fish in France: study of the course of natural infection by combined use of viral and seroneutralization test and eradication attempts].

Infectious haematopoietic necrosis (IHN), a rhabdoviral infection of salmonid fish, was considered to be an exotic disease in Europe until it was recognized in France and Italy in 1987. In France, the existence of this new condition led the authorities in charge of animal health to order epidemiological studies to be undertaken. These studies were based upon virological, serological and experimental diagnostic methods and also encompassed disease eradication attempts. Studies were conducted at 7 fish farming sites, involved 1,545 salmonid fish, of which 848 were sacrificed, and represented 262 virological examinations and 1,782 serum neutralization tests. The presence of the IHN virus was detected in the 7 trout farm fish populations that were located in 5 regions, one of which was situated 600 km from the place where the first isolation of IHN virus was made. Moreover, 6 out of 7 rainbow trout populations reared in these farms also harboured viral haemorrhagic septicaemia virus (VHSV) often resulting in overt disease. Rainbow trout was the only salmonid fish species found infected with IHN. Overt infection, which was observed in fish ageing less than 2,200 degrees-days, always occurred at water temperatures below 14 degrees C, and the younger fish were more susceptible (mortality rate > or = 80%). Although the IHN virus is easily isolable from fish undergoing overt infection, it was hardly detectable in survivors until they were adults, at which stage the virus was shedded via sexual products which constituted suitable materials for virological examination and disease transmission assays. Survivors of overt and dormant IHN infection developed consistent immune response and special attention was paid to neutralizing antibodies (NAb) to IHN virus. The detection of such NAb in fish from infected farming sites or other NAb from presumably IHN-free sites, correlated fairly well with the presence and further detection of IHN virus among such fish populations. Our data provide arguments for considering the serological technique as a suitable means of completing fish health surveillance programmes for IHN. Although our results are in agreement with part of the existing knowledge on IHN, they differed in several points: rainbow trout was the only susceptible fish species; overt IHN was always recorded in juveniles and at water temperatures below 14 degrees C; IHN virus could not be recovered from the mucus of infected broodfish; IHN infection usually coexisted with VHS infection in same fish population; and serology was widely and successfully used for the diagnosis of IHN.

Animals↗
PubMed1997

Toxorhynchites-fluorescent antibody system for the detection of bluetongue virus from Culicoides midges (Diptera: Ceratopogonidae).

A new system, the Toxorhynchites-fluorescent antibody (TFA) test in which the larvae of Toxorhynchites splendens mosquitoes were used for the detection of bluetongue virus (BTV) from Culicoides midges, was developed. Twenty-seven pools of Culicoides midges were collected from bluetongue-prone areas of Tamil Nadu by use of the light-trap and suction-trap methods. A suspension of each pool was injected intrathoracically into T. splendens IV instar larvae and inoculated onto Vero cell monolayers. An indirect fluorescent antibody technique and an immunoperoxidase test were used to detect BTV antigen in smears of crushed midges, crushed larval head smears after incubation for 7 d at 28 degrees and cell monolayers showing cytopathic effects 48 h post inoculation. The suspensions were also injected intravenously into embryonated chicken eggs, and the characteristic BTV-induced lesion(s), viz. cherry-red appearance of embryos, were observed after 48 h. Virus was confirmed by a qualitative neutralization test conducted simultaneously in embryonated chicken eggs. A total of seven out of 27 samples (26%) were positive for the presence of BTV antigen in all the diagnostic systems used. Since BTV propagates readily in experimentally infected T. splendens larvae and the BTV antigen can be detected by the fluorescent antibody technique with a sensitivity comparable to that for virus propagated in tissue culture and embryonated eggs, the TFA system can be adopted as a new method for the isolation of BTV from vectors. The advantages of the TFA system are discussed.

Animals↗
PubMed2006

Monoclonal antibody-based competitive enzyme-linked immunosorbent assay for detecting and quantifying West Nile virus-neutralizing antibodies in horse sera.

A rapid immunoassay for detecting and quantifying West Nile virus (WNV)-neutralizing antibodies in sera was developed as an alternative to the plaque reduction neutralization test (PRNT), the gold standard test for WNV. The assay is a competitive, enzyme-linked immunosorbent assay using neutralizing monoclonal antibody 5E8 (NT-ELISA). A cutoff percent inhibition (PI) value of 35% (mean PI plus 3 standard deviations), with a specificity of 99%, was established based on analysis of 246 serum samples from horses free of WNV. The NT-ELISA detected neutralizing antibodies in all sera collected 7 or 14 days postinoculation from mice (n = 11) infected with lineage I (strain NY385-99) or II (strain B956) WNV. When sera from WNV-vaccinated horses (n = 212) were tested by NT-ELISA and PRNT, the NT-ELISA gave a positive result for 96.1% (173/180) of the PRNT-positive sera and 3.1% (1/32) of the PRNT-negative sera. Discrepancies between the two tests were observed mainly with sera with low PRNT(90) titers (expressed as the reciprocal of the highest dilution yielding > or = 90% reduction in the number of plaques) for WNV or low PIs by NT-ELISA. The overall agreement (k value) between the two tests was 0.86. A good correlation (r(2) = 0.77) was also observed between the tests for endpoint titration of sera (n = 116). In conclusion, the newly developed NT-ELISA may be a good alternative serologic assay for detecting WNV that can be used for large-scale testing of WNV-neutralizing antibodies in multiple species.

Animals↗