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 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*

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*

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

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

PURPOSE: The 2000-2001 measles epidemic resulted in more than 50,000 cases with the highest attack rate occuring in infants less than one year of age, indicating the necessity of measles immunization before 12 months of age when a measles outbreak occurs again. The study was conducted to measure maternal measles antibody in infants by plaque reduction neutralization test(PRN), for the first time in Korea, to assess the optimal age for measles vaccination before the first birthday, when necessary. METHODS: Sera were obtained from 95 infants younger than 12 months of age who were healthy or recovered from mild llnesses, and had not had measles vaccination, measles infection, or blood transfusion. Measles antibodies were measured by PRN. RESULTS: Geometric mean titers and seropositive rates of measles antibody measured by PRN were 879.7 mIU/mL(100.0%), 690.0 mIU/mL(83.3%), 182.7 mIU/mL(50.0%), 91.3 mIU/mL(50.0%), 32.2 mIU/ mL(0.0)%, 25.1 mIU/mL(0.0%), 18.1 mIU/mL(0.0%), 38.4 mIU/mL(25.0%), 27.1 mIU/mL(0.0%), 31.2 mIU/mL(0.0%), 54.3 mIU/mL(0.0%), and 27.1 mIU/mL(0.0%) from 0 to 11 months respectively. CONCLUSION: By PRN, which was used for the first time to measure the measles antibody in Korea, placentally transferred measles antibody was detected in all newborns tested and decreased reciprocally to the age of infants, leaving almost all infants older than four months seronegative. These results indicate that measles vaccination at six months of age or older, which is the current recommendation during the period of epidemic issued by the Korean Society of Pediatrics, should not cause the primary vaccine failure. It seems advisable to utilize PRN further in order to find the optimal schedule for measles vaccination to infants born to women who were vaccinated.
Antibodies* ; Appointments and Schedules ; Blood Transfusion ; Female ; Humans ; Immunization ; Infant* ; Infant, Newborn ; Korea ; Measles* ; Neutralization Tests* ; Pediatrics ; Vaccination

PURPOSE: The development of a genetically modified live rabies vaccine applicable to wild raccoon dogs is necessary for the eradication of rabies in Korea. Thus, we constructed a recombinant rabies virus (RABV) called the ERAGS strain, using a reverse genetic system and evaluated its safety and efficacy in mice and its safety and immunogenicity in raccoon dogs. MATERIALS AND METHODS: ERAGS, which has Asn194Ser and Arg333Glu substitutions in the glycoprotein, was constructed using site-directed mutagenesis. Mice were inoculated with the ERAGS strain (either 10(5.0) or 10(7.0) FAID(50)/mL) via intramuscular (IM) or intracranial injections and then challenged with a virulent RABV. Raccoon dogs were administered the ERAGS strain (10(8.0) FAID(50)/mL) either orally or via the IM route and the immunogenicity of the strain was evaluated using fluorescent antibody virus neutralization tests. RESULTS: The ERAGS strain inoculated into murine neuroblastoma cells reached 10(7.8) FAID(50)/mL at 96-hour post-inoculation. The virus was not pathogenic and induced complete protection from virulent RABV in immunized 4- and 6-week-old mice. Korean raccoon dogs immunized with the ERAGS strain via IM or oral route were also safe from the virus and developed high titer levels (26.4-32.8 IU/mL) of virus-neutralizing antibody (VNA) at 4 weeks post-inoculation. CONCLUSION: The ERAGS RABV strain was effectively protective against rabies in mice and produced a high VNA titer in raccoon dogs.
Animals ; Glycoproteins ; Korea ; Mice* ; Mouth ; Mutagenesis, Site-Directed ; Neuroblastoma ; Neutralization Tests ; Rabies Vaccines ; Rabies virus* ; Rabies* ; Raccoon Dogs* ; Raccoons* ; Vaccines

Since HantavaxTM, formalin inactivated Hantaan virus vaccine (10,240 ELISA units/ml), has been developed in 1990 to prevent against haemorrhagic fever with renal syndrome (HFRS) caused by Hantaan or Seoul virus, it has been commercially available in Korea. Twenty-one healthy people were booster shot once and twice after primary basic vaccination with HantavaxTM. Seroconversion rates were measured by immunofluorescent antibody technique (IFAT), enzyme-linked immunosorbent assay (ELISA), high density composite particle agglutination (HDPA), and plaque reduction neutralization test (PRNT). Seroconversion rates of 21 vaccinees at one year after primary basic vaccination were 52.3%, 95.2%, 0.0%, 47.6%, and 28.6%, and 13 vaccinees of one month after 1st booster vaccination were 100%, 100%, 30.7%, 100% and 100% by IFAT, ELISA (IgG, IgM), HDPA and PRNT, respectively. Seroconversion rates declined slightly by twenty months, and they were 84.6%, 92.3%, 0.0%, 84.6% and 69.2% by IFAT, ELISA (IgG, IgM), HDPA and PRNT, respectively. Seroconversion rates of 9 vaccinees at three months after 2nd booster vaccination were 100%, 100%, 0.0%, 100%, and 88.9%, and 16 vaccinees at one year after the 2nd booster vaccination were 87.5%, 93.8%, 0.0%, 87.5% and 81.3% by IFAT, ELISA (IgG, IgM), HDPA and PRNT, respectively. Based on the above result HantavaxTM has proved a vigorous anamnestic response after the 1st and the 2nd booster vaccination and has persisted higher fluorescence, agglutination and neutralizing antibody titers in vaccinees.
Agglutination ; Antibodies, Neutralizing ; Enzyme-Linked Immunosorbent Assay ; Fever* ; Fluorescence ; Formaldehyde ; Hantaan virus ; Korea ; Neutralization Tests ; Seoul virus ; Vaccination

BACKGROUND: The specificity of HBsAg enzyme immunoassay (EIA) has been previously reported between 95% and 100% for blood donor screening in Korea. Considering that Korea is highly endemic in HBV infection, it is highly recommended that blood donors showing true positive for HBsAg were permanently deferred from donation. Identification of false-positive results by a confirmation assay would be a necessary step for this purpose. This study was intended to evaluate LG HBsAg Confirm (LG Chemicals Corp., Seoul, Korea) kit as a confirmation test and know the positive predictive value for HBsAg screening results. METHODS: LG HBsAg Confirm reactivities were evaluated in 279 patients and 185 blood donor samples, all of which were positive in HBsAg EIA. Patients samples were positive in both HBsAg EIA and HBV DNA. Confirm positive was determined according to the following 2 step criteria: (1) the percent neutralization is 50% or more (first-step neutralization), or (2) if not, the percent neutralization after 1:1,000 dilution of original sample is 50% or more (second-step neutralization). RESULTS: LG HBsAg Confirm kit confirmed all 279 patients~ sera as positive. All of 185 blood donor samples showed true positive results. First-step neutralization confirmed 157 sera (33.8%) as positive and second-step neutralization confirmed 307 sera (66.2%) among 464 samples. CONCLUSION: Performance of LG HBsAg Confirm was so excellent that all the samples showing positive in both HBsAg EIA and HBV DNA tests could be determined as confirm positive.
Blood Donors ; DNA ; Hepatitis B Surface Antigens* ; Humans ; Immunoenzyme Techniques ; Korea ; Mass Screening ; Neutralization Tests ; Sensitivity and Specificity ; Seoul