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PubMedDate not supplied

An ELISA suitable for the detection of rabies virus antibodies in serum samples from human vaccinated with either cell-culture vaccine or suckling-mouse-brain vaccine.

An indirect ELISA for determination of post-vaccination rabies antibody was applied. Purified rabies virus was used as antigen to coat plates, and staphylococcal protein A linked with horseradish peroxidase was used for detecting IgG antibody in human sera. Sera from humans, vaccinated with cell-culture vaccine or suckling-mouse-brain vaccine, were examined. ELISA results were compared to those obtained from the virus neutralization test. The mean and standard deviation of OD were determined for 126 negative sera (pre-vaccination) and for 73 sera from vaccinated persons showing antibody titers lower than 0.5 IU/ml. Results were defined as ELISA -positive, -negative or -doubtful. Establishment of a doubtful region reduced the number of sera otherwise classified as positive (false-positive sera). In this way, the sensitivity, specificity and agreement values were respectively 87.5%, 92.4% and 88.5%. No significant differences were observed in these values when the group vaccinated with cell-culture vaccine and the group vaccinated with suckling-mouse-brain vaccine were compared. It was shown that much of the disagreement between the values obtained by neutralization test and ELISA occurred in sera obtained at the beginning of the immunization process, and was probably due to the presence of IgM in the serum samples, detected only by the former test. This ELISA method can be used as a screening test in rabies laboratories regardless of the kind of vaccine used for immunization.

Animals↗
PubMed1987

Standardization of a plaque assay for Lassa virus.

The plaque reduction neutralization test (PRNT) has been used routinely in serological studies with such arenaviruses as Junin, Machupo, and Parana. However, difficulties have been encountered in using the PRNT for LCM virus, while conflicting views have been expressed about the reliability and efficacy of the test with Lassa virus. We have therefore investigated and evaluated the plaque assay for Lassa virus. In addition, the suitability of the PRNT for determining the potency of a serum and its efficacy in passive immunization for the treatment of Lassa fever was also investigated. The Lassa virus plaque assay satisfied the criteria proposed by Cooper [1961] for determining satisfactory plaque technique. Lassa virus plaques appear within 3 days of inoculating Vero cell cultures. By day 5, the plaques are clearly defined, discrete, and measure 1.5 to 2.0 mm. In the plaque reduction neutralization test, the use of native non-inactivated serum was required for a reliable and reproducible determination of serum antibody titer. The potency and suitability of a serum for Lassa fever serotherapy was determined by the use of a constant serum-varying virus (CS-VV) and/or a constant virus-varying serum (CV-VS) PRN technique.

Animals↗
PubMed1983

Antigenic relationships of murine coronaviruses.

Two serological tests were used to examine the antigenic relationships between murine hepatitis viruses that cause different diseases in mice. Antisera prepared by immunization of mice with the individual viruses were tested for their ability to neutralize both the homologous immunogen and the other viruses. By a plaque reduction neutralization test, each antiserum was found to be specific for the immunizing virus; however, there was substantial cross-reactivity, indicating the viruses were closely related. By kinetic neutralization, two of the viruses tested, MHV-JHM and MHV-2, were found to be antigenically distinct. MHV-3 and MHV-A59 were found to be antigenically very similar but distinct. These data show that kinetic neutralization is a more precise method for determining the antigenic relationships between murine coronaviruses.

Animals↗
PubMed1993

Serological study of Japanese encephalitis in Nepal.

Antibodies against Japanese encephalitis virus (JEV) were examined in 356 serum samples from individuals visiting Tribhuvan University Teaching Hospital using neutralization test. A total of 13.2% (47/356) seropositivity was observed. Antibody positivity against both Nakayama-NIH and Beijing-1 strains was seen in 7.9% subjects. Infection by Nakayama-NIH strain alone was seen to be 4.2% while 1.1% of study populations were found to be infected only by Beijing-1 strain. High antibody titer was observed in the 20-40 years age-group and did not increase with age. Seropositivity was more common in zone-A (Tarai) area compared to zone-B (Hills) and zone-C (Mountains). Spectrum of antigenicity of JEV in zone-A as shown by neutralization test was identical to Indian isolates (strains). Difference in seropositivity was observed against Nakayama-NIH and Beijing-1 strain in zone-B and C indicating recent spread of JEV in these areas.

Adolescent↗
PubMed1976

An immunological method for detection of the carrier of hemophilia B.

This paper presents the results of an immunological study of hemophilia B and its carriers which used two kinds of antibodies, a heterologous antibody of high specificity and a homologous antibody developed in a patient with severe hemophilia B. 1. The factor IX related antigen for hemophilia B could be determined by a neutralization test and not by a precipitation reaction. 2. The activity of factor IX in a definite carrier of hemophilia B was significantly lower than that of factor VIII in a definite carrier of hemophilia A. 3. In hemophilia B, there were no differences between the factor IX antigen determined by either the heterologous rabbit antibodies or the homologous antibodies. And there was no discrepancy between the factor IX antigen and the factor IX activity. Therefore, we cannot use this discrepancy for the detection of a carrier of hemophilia B. 4. However, there was a discrepancy between the factor IX antigen determined by the neutralization test and the factor IX procoagulant activity in the patients of both hemophilia BM and hemophilia B+. The identical results were obtained in the cases of carriers of both hemophilia BM and hemophilia B+. These facts are very useful for the detection of carriers of hemophilia BM and hemophilia B+.

Antigens↗
PubMed1979

Observations on the antigenicity and serological relationships of stocks of Trypanosoma congolense from East and West Africa.

Antigenic relationships of 4 stocks of Trypanosoma congolense from different parts of Africa were examined by immunofluorescence (IFAT) and neutralization tests. Antisera to each stock were obtained from rabbits infected with trypanosomes transmitted by Glossina morsitans. Trypanosomes for use as antigens were obtained from local skin reactions developing on rabbits infected with 2 of the stocks. Using the IFAT and antisera at end-point dilutions approximately 40% of the trypanosomes fluoresced strongly and a further 30% less intensely with homologous antisera, indicating antigenic heterogeneity among the trypanosomes developing in the skin. Using antisera at low dilutions some samples gave cross-reactions with trypanosomes of heterologous stocks, but at higher dilutions there were no cross-reactions with either of the antigens. The lack of cross-reactions at high antiserum dilutions was interpreted as indicating antigenic differences between the 4 trypanosome stocks. Using neutralization tests only homologous antisera reduced the infectivity of trypanosome suspensions. Overall, these observations indicated that there were at least 3 different strains of T. congolense among the 4 stocks examined.

Animals↗
PubMed1973

Hemagglutination-inhibition test in rhinovirus infections of volunteers.

The hemagglutination-inhibition (HI) test for antirhinovirus antibody was carried out on paired sera from volunteers inoculated with rhinovirus type 3 or type 4 (RV4). The HI test gave results which paralleled the neutralization test and was at least as sensitive as a microneutralization method for detection of serotype-specific antibody. Although high levels of HI antibody in the serum were associated with protection from infection, in the case of RV4 low serum HI antibody levels did not necessarily imply susceptibility to challenge with small doses of virus. HI activity could be measured in concentrated nasal-washing fluids, and this antibody also seemed relevant to protection against infection.

Adolescent↗
PubMed1999

[Study on etiology of acute hemorrhagic conjunctivitis in Qingdao during 1997].

OBJECTIVE: To study the etiology of acute hemorrhagic conjunctivitis (AHC) in Qingdao during 1997. METHODS: During the AHC epidemic season viruses from the conjunctival swabs were isolated in Hela and Hep-2 cell cultures and were identified by neutralization test. RESULTS: All isolated virus strains were identified as (CA24) v and adenoviruses (Adv) by neutralization test with antisera of CA24 v, Echo virus 70(EV70), CA24, CA24 v of Beijing local strain, Ad3, Ad7 and Ad11. CONCLUSION: In 1997, a small epidemic of acute hemorrhagic conjunctivitis was caused by adenoviuses and CA24 v.

Conjunctivitis, Acute Hemorrhagic↗
PubMed1983

[Detection of laboratory infections caused by Junín virus using the neutralization and immunofluorescence technics comparatively].

To study Junin virus infection among laboratory workers and to compare immunofluorescence and neutralization tests, blood samples were taken from 48 individuals, of which 42 were considered high risk personnel. None of the 16 low risk workers exhibited antibodies. Neutralizing antibodies were detected in 15 high risk laboratory workers. Nine of the latter were already known to carry antibodies from a previous survey in 1978. Titers detected were either at previous levels or slightly higher. Of the remaining 6 out of the 15 positive cases, 3 showed mild clinical and subclinical infection, equivalent to a 12% incidence rate over the 1978-1980 period. An adequate correlation was observed between neutralization and immunofluorescence test: 66.6% for both positive tests and 97.1% for both negative tests. Although the immunofluorescence test ies easier to perform the neutralization test appears to be more reliable clinically. The overall prevalence rate of neutralizing antibodies among non-vaccinated personnel was almost 19%, which warns against the health hazard involved in Junin virus handling.

Antibodies, Viral↗
PubMed1976

Humoral immunity in experimental syphilis. II. The relationship of neutralizing factors in immune serum to acquired resistance.

Evidence for a humoral mechanism in immunity to experimental syphilis was provided by the demonstration of immune rabbit serum factor(s) capable of inactivating virulent Treponema pallidum, Nichols strain, in an in vitro-in vivo neutralization test. After intratesticular infection, rabbits were bled periodically and their resistance to reinfection was determined by challenge with T. pallidum. The results of challenge showed that resistance to reinfection begins to develop by 11 days after infection, becomes complete by 3 months, and persists for at least 2 years. In the neutralization test, a mixture of treponemal suspension and serum from the infected animals was incubated anaerobically at 34 degrees C and the virulence of the treponemes was determined by intradermal inoculation into normal rabbits. Complete inactivation of treponemes by immune serum required heat-stable and heat-labile (56 degrees C, 30 min) serum components and 16 hr of incubation, and was accelerated by pre-incubation of the treponemes for 4 hr with nonimmune serum but not by 100 mug/ml of added lysozyme. Serum-neutralizing activity, first demonstrable 1 month postinfection, was quantitated by a neutralizing endpoint (NEP). A relatively close quantitative correlation was shown between the development of resistance to symptomatic reinfection and the appearance and persistence of both TPI antibody and neutralizing serum factor(s). The nature of the serum factor(s), the mechanism of treponemal inactivation, and the application of the test in assessing the immune status are discussed.

Animals↗
PubMed1980

Antibody development in garter snakes (Thamnophis spp.) experimentally infected with western equine encephalitis virus.

Garter snakes (Thamnophis spp.) have been considered to possibly play an important role in the ecology of western equine encephalitis (WEE) virus. Serological tests (hemagglutination-inhibition, complement-fixation, neutralization test in mice, and plaque neutralization) to detect antibody in these reptiles following laboratory exposure t this virus have, in our experience, been unsatisfactory. A new test, the snake globulin precipitation (SGP) test, has been developed and we consider it to be reliable in detecting antibody in WEE virus-infected garter snakes. Antibody has been detected in these snakes over 4.5 years following inoculation with WEE virus. The SGP test should be a valuable tool in obtaining further information regarding the possible role of these cold-blooded vertebrates in the ecology of this important arbovirus.

Animals↗
PubMed2001

Genomic and serological diversity of bovine viral diarrhea virus in Japan.

Genomic properties of 62 field isolates of bovine viral diarrhea virus (BVDV) collected from 1974 to 1999 in Japan were investigated. The 5' untranslated region (UTR) was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) and the 244 to 247 base nucleotide sequences were determined. Serological properties were also characterized by the cross-neutralization test using antisera against the representative strain of the classified genotype. Using phylogenetic tree analysis, BVDV 1 was subdivided into two major clusters, BVDV-1a (29 isolates) and BVDV-1b (27 isolates). In group 1a, 3 differed from the other viruses, and were classified in a branch assigned as 1a'. However, 4 isolates (So CP/75, 190 CP, 190 NCP and KS86-1-NCP) could not be assigned to group 1a or 1b. In comparison with the published sequence data, KS86-1-NCP, 190 CP and 190 NCP were similar to the Southern Africa isolates that have recently been proposed as BVDV 1c. The 5' UTR sequence of So CP/75 was unique among those of BVDV 1, suggesting that the isolate should be classified into a new genotype. Only 2 out of 62 isolates collected in 1989 and 1990 were identified as BVDV 2. The results of the cross-neutralization test strongly supported these data, suggesting a close correlation between the 5' UTR sequence and the antigenicity of BVDV.

5' Untranslated Regions↗
PubMed1986

Differing contribution of various effector cells in the elimination of syngeneic or allogeneic cells.

The growth of Meth A (MA) tumors was suppressed in tumor-antigen-specific manner in BALB/c mice immunized with mitomycin C-treated MA (MMC-MA) cells in saline or in Freund's complete adjuvant (FCA). The antitumor activity of their peritoneal exudate cells (PEC) was detected by in vivo neutralization test and in vitro cytostasis assay but not by in vitro cytolysis assay. Positive delayed footpad reaction was elicited by footpad injection of MMC-MA cells in such immunized mice, before or after the inoculation of viable MA cells. Expression of cytostatic activity in PEC required the interaction of non-adherent and adherent cells. Normal PEC could exert the cytostatic activity in the presence of a nonadherent population of immune PEC. These findings suggest that cytostatic macrophages are activated after the interaction between sensitized lymphocytes and tumor-specific antigens and that they play an important role in the principal effector mechanism in this syngeneic system. On the other hand, immunization with MMC-MA in FCA or viable MA cells also induced PEC the antitumor activity detected by in vivo neutralization test in allogeneic C57BL/6 hosts. Immunization with viable MA cells induced not only cytolytic but also cytostatic activity, whereas, immunization with MMC-MA in FCA induced cytostatic activity but not cytolytic activity. In contrast to a syngeneic system, cytolytic activity was effectively induced against allogeneic MA cells together with cytostatic activity. We conclude that there are various effector cells contributing to the elimination of syngeneic or allogeneic murine tumor cells.

Animals↗
PubMedDate not supplied

ELISA for detection of IgM and IgG antibodies to sandfly fever Sicilian virus.

An enzyme-linked immunosorbent assay (ELISA) was developed to detect specific human immunoglobulin G and M antibodies to sandfly fever Sicilian (SFS) virus. Acute and early convalescent serum pairs with greater than or equal to 7 days between the 2 specimens were available from 20 patients and all showed significant optical density (OD) increase and significant titre rise (greater than or equal to 4-fold) by IgG ELISA. However, negative or borderline-positive sera were found as late as 11 days after onset of symptoms when tested by IgG ELISA. Specific IgM antibodies were detected during the first week of symptoms, and maximum OD values were obtained during the first 4 weeks after onset of disease. The IgM OD values declined over the following 3-9 months. All sera collected later than 14 months post-onset were negative by IgM ELISA. The combination of early antibody response and the need to test only one serum specimen gives IgM ELISA an advantage over IgG ELISA in patients diagnosis. The IgG ELISA was also evaluated as a seroepidemiological tool and compared to a plaque reduction neutralization test (PRNT) using sera from a normal Cypriot population. Of 183 sera tested, 34 (19%) were positive in plaque reduction neutralization tests (PRNT) and 113 (62%) by IgG ELISA. A number of PRNT-negative sera were strongly positive by IgG ELISA and also by indirect immunofluorescence test, which may suggest the presence of a virus related to SFS in Cyprus which has not yet been isolated.

Acute Disease↗
PubMedDate not supplied

Antigenic diversity of infectious bursal disease viruses.

Statistically significant antigenic differences were detected among serotype I infectious bursal disease viruses (IBDV) using the virus-neutralization test. Eight serotype I commercial vaccine strains, five serotype I field strains, and two serotype II field strains were tested. Hyperimmune guinea pig antisera against heterologous and homologous IBDV strains were used in cross-neutralization tests. Relatedness values were calculated from geometric mean antibody titers based on a minimum of three tests. Six subtypes were distinguished among the 13 serotype I strains tested.

Animals↗
PubMed2002

Hantavirus infections in Latvia.

In order to investigate the presence of hantavirus infections in Latvia, 333 randomly selected human serum samples were screened using an enzyme-linked immunoassay. Fifteen samples were positive for hantavirus-specific IgG and were subsequently serotyped using a focus reduction neutralization test. Fourteen of these samples neutralized at least one of the hantaviruses included in the test, indicating a 4.2% overall seroprevalence in Latvia. Among 14 focus reduction neutralization test-positive sera, specific reactivity (at least 4-fold higher endpoint titer) of neutralizing antibodies was as follows: six sera were specific for Saaremaa hantavirus, three showed equal titers to Saaremaa and Dobrava hantaviruses, and five showed the highest endpoint titers to Puumala hantavirus. Hantavirus infections were confirmed in individuals residing in 11 of 26 investigated counties. The sex ratio was 1:2.5 (M:F), and the antibody prevalence increased with age. This is the first report on the presence of hantavirus infections in Latvia, and the results indicate that two hantaviruses pathogenic to man, Saaremaa virus and Puumala virus, are widely distributed in this country.

Adult↗
PubMed1975

Arbovirus surveillance in Florida: wild vertebrate studies 1965-1974.

Wildlife species from 38 of Florida's 67 counties were surveyed over a 10 year period for the presence of antibody to the five major arboviruses circulating in the state. The routine screening of 7891 sera from wild birds and mammals via the hemagglutination-inhibition (H1) test with selected reactors subjected to serum neutralization testing has 1) provided information regarding geographic distribution and seasonality of circulation of these viruses 2) identified enzootic foci of infection and those species of wildlife most commonly infected and 3) documented the potential value of certain wild mammals as indicators of St. Louis Encephalitis and Venezuelan equine encephalomyelitis virus activity prior to the detection of human cases. Limited studies of Tamiami and Tensaw virus on sera from mammals collected for other purposed provided additional baseline information on the activity of these viruses in Florida mammals. Isolations of eastern equine encephalomyelitis virus were made from the heart of a loggerhead shrike (Lanius excubitor), Tensaw virus from the brain of a gray fox (Urocyon cinereoargenteus), and Keystone virus from the heart of a bluejay (Cyanocitta cristata).

Animals↗