The virus neutralization (VN) test was used to determine potency of the infectious bronchitis (IB) vaccine. The results of VN, hemagglutination inhibition (HI), and enzyme-linked immunosorbent assay (ELISA) were compared with those of the IBV M41. The r² values between VN and HI titers and the ELISA antibody titer were 0.8782 and 0.0336, respectively, indicating a high correlation between VN and HI, but not VN and ELISA. The Cohen's kappa coefficient between the VN titer of 2 log₁₀ and HI titer of 5 log₂ was 0.909. Our results showed that VN could be replaced with HI for testing the potency of IBV M41.
Bronchitis ; Enzyme-Linked Immunosorbent Assay* ; Hemagglutination Inhibition Tests* ; Hemagglutination* ; Infectious bronchitis virus* ; Neutralization Tests* ; Vaccine Potency*

PURPOSE: For evaluating the immunogenicity of an influenza vaccine, the microneutralization (MN) test has a higher sensitivity and specificity as compared to the hemagglutination inhibition (HI) test. However, the MN test is more time consuming and is difficult to standardize. We performed the MN test to determine its usefulness as an alternative or complementary test to the HI test for evaluating the immunogenicity of influenza vaccines. METHODS: We compared the MN test with the HI test using 50 paired samples taken from a previous clinical study (2008-2009) in Korean children under 18 years of age. RESULTS: The linear correlation coefficients of the 2 tests for H3N2, H1N1, and influenza B were 0.69, 0.70, and 0.66, respectively. We identified a high index of coincidence between the 2 tests. For an influenza vaccine, the postvaccination seroprotection rates and seroconversion rates determined by the MN test were 78.0% and 96.0%, 90% and 42.0%, and 42.0% and 48.0% for H3N2, H1N1, and influenza B, respectively. Geometric mean titer fold increases of H3N2, H1N1, and influenza B were 2.89, 5.04, and 4.29, respectively, and were 2.5-fold higher. We obtained good results in the evaluation of the immunogenicity of the 2008-2009 seasonal influenza vaccines. CONCLUSION: We found that the MN test was as effective as the HI test. Therefore, we suggest that the MN test can be used as an alternative or complementary test to the HI test for evaluating the immunogenicity of influenza vaccines.
Child ; Hemagglutination ; Hemagglutination Inhibition Tests ; Humans ; Influenza Vaccines ; Influenza, Human ; Neutralization Tests ; Seasons ; Sensitivity and Specificity

The seroprevalence of Japanese encephalitis virus (JEV) among equines was evaluated from January 2006 to December 2009 in 13 different states of India by hemagglutination inhibition (HI) test and virus neutralization test (VNT). Antibodies against JEV were detected in 327 out of 3,286 (10%) equines with a maximum prevalence reported in the state of Manipur (91.7%) followed by Gujarat (18.5%), Madhya Pradesh (14.4%), and Uttar Pradesh (11.6%). Evidence of JEV infection was observed in equines in Indore (Madhya Pradesh) where a 4-fold or higher rise in antibody titer was observed in 21 out of 34 horses in November 2007 to October 2006. In March 2008, seven of these horses had a subsequent 4-fold rise in JEV antibody titers while this titer decreased in nine animals. JEV-positive horse sera had a JEV/WNV (West Nile virus) ratio over 2.0 according to the HI and/or VNT. These results indicated that JEV is endemic among equines in India.
Animals ; Encephalitis, Japanese/blood/epidemiology/*veterinary ; *Equidae ; India/epidemiology ; Neutralization Tests ; Seroepidemiologic Studies ; Time Factors

A new alternative rabies bait vaccine strain named ERAG3G, which is applicable to wild animals, was developed to eliminate rabies in South Korea. In this study, the safety and immunogenicity of the strain was evaluated in Korean raccoon dogs. The ERAG3G was propagated in BHK/T7-9 cells. Korean raccoon dogs were administered ERAG3G (1 ml, 10(8.0) FAID50/ml) orally or intramuscularly to evaluate its safety and immunogenicity. The raccoon dogs were observed for 70 days after administration, and immunogenicity was measured using a fluorescent antibody virus neutralization test. The ERAG3G strain was not pathogenic to Korean raccoon dogs immunized via the intramuscular or oral route. Raccoon dogs administered the candidate vaccine via the oral route developed high virus neutralizing antibody (VNA) titers ranging from 13.7 to 41.6 IU/ml 70 days post administration. Raccoon dogs inoculated intramuscularly with the ERAG3G strain developed moderate VNA titers ranging from 0.5 to 13.7 IU/ml. These findings suggest that the ERAG3G strain is safe and induces a protective immune response in raccoon dogs.
Animals ; Animals, Wild ; Antibodies, Neutralizing ; Korea ; Neutralization Tests ; Rabies virus* ; Rabies* ; Raccoon Dogs* ; Raccoons*

Anti-Sda is of no clinical significance, because it rarely causes hemolytic transfusion reactions. Even when its presence is suspected during antibody screening test, further identification of the antibody is usually not performed. We experienced a case of anti-Sda in 73 yr-old male patient showing mixed field agglutination by microcolumn agglutination. Antibody specificity could not be identified by conventional antibody identification test, and it was proven to be anti-Sda by urine neutralization test. In spite of its little clinical significance, it may give incompatible crossmatching results reacting with Sda antigen, which occurs at a high frequency in general population. When incompatible crossmatch results arising from anti-Sda are suspected, the problem may be solved by using the urine-neutralized serum of in crossmatching test.
Agglutination ; Antibody Specificity ; Blood Group Incompatibility ; Humans ; Male ; Mass Screening ; Neutralization Tests

PURPOSE: Porcine reproductive and respiratory syndrome virus (PRRSV) leads to major economic losses in the swine industry. Vaccination is the most effective method to control the disease by PRRSV. MATERIALS AND METHODS: In this study, the efficacy of a glycoprotein (GP) 5-modified inactivated vaccine was investigated in pigs. The study was performed in three farms: farm A, which was porcine reproductive and respiratory syndrome (PRRS)-negative, farm B (PRRS-active), which showed clinical signs of PRRS but had not used vaccines, and farm C (PRRS-stable), which had a history of endemic PRRS over the past years, but showed no more clinical signs after periodic administration of modified live virus vaccine. RESULTS: The inactivated vaccine induced great enhancement in serum neutralizing antibody titer, which was sufficient to protect pigs from further infections of PRRSV in a farm where pre-existing virus was circulating. CONCLUSION: These results indicated that vaccination with the inactivated vaccine composed of viruses possessing deglycosylated GP5 would provide enhanced protection to pigs from farms suffering from endemic PRRSV.
Antibodies, Neutralizing ; Glycoproteins ; Neutralization Tests ; Porcine Reproductive and Respiratory Syndrome* ; Porcine respiratory and reproductive syndrome virus* ; Swine* ; Vaccination ; Vaccines ; Vaccines, Inactivated

OBJECTIVETo investigate the characteristics and dynamic changes of serum neutralizing antibody response in patients with primary infection of dengue virus type 1 (DENV-1).

METHODSSerum samples were obtained from the same patients with primary infection of DENV-1 within 2 weeks after symptom onset in 2006 and in 2010. A group-specific DENV NS1 capture ELISA-based micro-neutralizing test (ELISA-MNT) capable of detecting neutralizing antibodies against all the 4 serotypes of DENV was used to test the neutralizing antibody titers against DENV in the serum samples. The neutralizing antibody titers against a standard strain and 2 clinically isolated strains of DENV-1 were detected in serum samples collected in 2010.

RESULTSCross-reactive neutralizing antibody response against all the 4 serotypes of DENV was found in both of the serum samples collected in 2006 and 2010, but the samples collected in 2006 showed stronger cross-reactive neutralizing antibody responses. The neutralizing antibody against DENV-2, rather than the anticipated DENV-1 antibody, had the highest titer in the samples collected in 2006, whereas the antibody against homologous DENV-1 had the highest titer in the samples obtained in 2010. The neutralizing antibody titers against the homologous DENV-1 was significantly higher in samples collected in 2010 (U=86.500, P=0.000), which also demonstrated significantly different neutralizing antibody titers against the 3 different strains of DENV-1 (Χ(2)=12.123, P=0.002).

CONCLUSIONThe production of cross-reactive neutralizing antibodies between the 4 serotypes of DENV is a characteristic of DENV infection, particularly during early infection, but only the homologous neutralizing antibody increases obviously over time. The titers of the neutralizing antibodies against different strains, even of the same serotype, may differ distinctly.

Antibodies, Neutralizing ; blood ; Antibodies, Viral ; blood ; Cross Reactions ; Dengue ; blood ; immunology ; Dengue Virus ; classification ; immunology ; Humans ; Neutralization Tests

To generate an epitope-mutated foot-and-mouth disease virus (FMDV) as a marker vaccine, the infectious clone pAsia 1-FMDV containing the complete genomic cDNA of Asia 1 type FMDV was used as backbone, the residues at positions 27 and 31 in the 3D gene were mutated (H27Y and N31R). The resulting plasmid pAsia 1-FMDV-3DM encoding a mutated epitope was transfected into BHK-21 cells and the recombinant virus rAsia 1-3DM was rescued. The recombinant virus showed similar biological characteristics comparable with the parental virus. In serological neutralization test the antisera against recombine virus have a good reactivity with parental virus. The antisera against the mutant virus were shown to be reactive with the mutated epitope but not the wild-type one. The results indicated that the two virus strains could be distinguished by western blotting using synthetic peptides. This epitope-mutated FMDV strain will be evaluated as a potential marker vaccine against FMDV infections.
Animals ; Cell Line ; DNA, Complementary ; Epitopes ; genetics ; Foot-and-Mouth Disease Virus ; genetics ; Immune Sera ; Neutralization Tests ; Transfection

In this study, three expression vectors encoding unmodified glycoproteins E1 and E2 from H77 (1a), Hebei (1b) and JFH1 (2a) strains were constructed to form pVRC-H77-E1E2, pVRC-HeBei-E1E2 and pVRC-JFH1-E1E2 expressing constructs. The protein expression was confirmed by immunofluorescene assay(IFA) and Western blot. The Lentiviral vector has the ability to package the cellular membrane into pseudo-particles. The plasmid expressing HCV E1-E2 glycoproteins in native form was co-transfected into 293FT cells with a lentiviral packaging plasmid (pHR'CMV delta R8.2)and a self-inactivated (SIN) transfer plasmid (pCS-CG) containing a reporter EGFP gene to produce infectious HCV pseudo-particles(pp). Flow cytometry assays showed that the HCVpp could infect Huh7 and Huh7-CD81, and the infectivity in Huh7-CD81 was about 2-3 times higher than that in Huh7 cells. Meanwhile, HCVpp could neither infect non-liver cells, for example, the 293 cells, nor HepG2 cell . Titration of HCVpp by p24 ELISA assay or infection assay showed that this HCVpp may contain 5-25 ng/mL p24 or 10(4)-10(5) TU (transducing unit)/ ml. An in vitro HCV neutralizing assays based on HCVpp (1a, 1b, 2a) were then established using AP33, a monoclone antibody with cross-neutralizing ability to different HCV strains. The neutralizing ability of the antibodies from HCV infected patients was further studied with this HCVpp system. In summary, three kinds of HCVpp (1a, 1b, 2a subtype) were successfully developed; In vitro HCV neutralizing assays based on HCVpp and SIN lentiviral system were established. This system paves a way for characterization of early steps of HCV infection (host tropisms, receptor binding, membrane fusion, et al. ) or screening anti-HCV drugs (such as inhibitor to virus entry). This system can be further applied to assess the human immune responses in HCV patients or evaluate HCV vaccine candidates.
Hepacivirus ; immunology ; Hepatitis C Antibodies ; immunology ; Hepatitis C, Chronic ; immunology ; Humans ; Neutralization Tests ; Viral Envelope Proteins ; immunology ; Virion ; immunology

We immunized sixty two healthy subjects with the five different viral titers (300, 500, 1000, 1500 and 2000 plaque forming unit; pfu) of the MAV/06 strain of live attenuated Varicella-zoster virus (VZV) in order to gain sufficient information on safety and immuogenicity as a vaccine strain. Humoral immunity of all vaccine recipients was tested by the fluorescent antibody to membrane antigen (FAMA) assay and Enzyme-linked immunosorbent assay (ELISA) for the quantitative detection of IgG antibody. We tested neutralized antibody in 62 subjects by plaque reduction neutralization test (PRNT50). All of thirty two subjects with initial seronegative response had antibody by FAMA method at four weeks after immunization with four different preparations of dosage. The geometric mean titers (GMTs) of VZV antibody to membrane antigen was 160.9 in 6 subjects with 1500 pfu group; 83.3 in 14 subjects with 1000 pfu group: 116.2 in 7 subjects with 500 pfu groups and 72.0 in 6 subjects with 300 pfu group. Thirty subjects who had VZV antibody at the time before immunization demonstrated elevated antibody titer by FAMA assay and PRNT50 test. Side reactions of the vaccination was not demonstrated in all cases.
Chickenpox* ; Enzyme-Linked Immunosorbent Assay ; Herpesvirus 3, Human ; Immunity, Humoral ; Immunization ; Immunoglobulin G ; Membranes ; Neutralization Tests ; Vaccination