OBJECTIVETo study the variation of specific antibody among convalescent of severe acute respiratory syndrome (SARS) patients through a three-year program.

METHODSSera samples were collected from SARS cases in the 5th, 20th and 35th month after onset of the illness. The SARS-CoV specific antibody was detected for all of them by ELISA and neutralized test simultaneously. The titer of neutralizing antibodies was calculated using Reed-Muench method, and the comparison between different time groups was analyzed regarding the variance of data on repeated measures after logarithm conversion.

RESULTS13, 17 and 13 sera samples were collected in the 5th, 20th and 35th month after onset. Results showed that despite the fact that the positive rates of ELISA antibody were 100%, 82.4% and 84.6% respectively,the neutralizing antibody was still positive for all the samples. The average neutralizing antibody titers were 1:43 (1:16-1:203), 1:36 (1:17-1:59) and 1:21 (1:10-1:39) on the 5th, 20th and 35th month after onset, and the differences were statistically significant (F = 60.419, P < 0.001). On the 35th month after the onset, 30.8% (4/13) of the patients were still having the neutralizing antibody level of above 1:36, but the neutralizing antibody level in another 30.8% (4/13) of the patients had decreased to as low as 1:10, when the cut-off level was set as 1:8.

CONCLUSIONResults of the study indicated that the neutralizing antibody of SARS cases could last for at least three years, but the sera specific antibody in SARS cases decreased gradually when time went by. However, neutralizing antibody in some of the cases decreased to a lower level on the 35th month. Further follow-up study was worthwhile to observe the long-lasting profile of antibody existence on SARS cases.

Antibodies, Neutralizing ; analysis ; Enzyme-Linked Immunosorbent Assay ; Follow-Up Studies ; Humans ; Severe Acute Respiratory Syndrome ; immunology

Effective and tolerable vaccination is an essential strategy to prevent Japanese encephalitis (JE) in endemic areas. Although the live attenuated SA 14-14-2 JE vaccine (LAJEV) has been widely used since its introduction, the systemic data of LAJEV was very rarely available in Korea. We conducted the open-label, prospective cohort study to assess the immunogenicity and safety of this vaccine. Ninety subjects were enrolled, and LAJEV in a 2-dose primary series was given with a 12-month interval. Neutralizing antibody titers were measured before and after each vaccination, and active monitoring for adverse events was performed. After the first dose, 91.1% of subjects had seroprotection with a geometric mean titer (GMT) of 40.9. Seroprotection rate after the second dose was 97%, and GMT showed an increase of 6.5-fold. Most adverse events following immunization were self-limited, and no serious adverse events were reported until 42 days after each dose. The 2-dose administration of LAJEV in the primary immunization schedule appeared to be highly immunogenic and safe.
Antibodies, Neutralizing/analysis/immunology ; Antibodies, Viral/analysis/immunology ; Antibody Formation ; Child, Preschool ; Cohort Studies ; Encephalitis, Japanese/*prevention & control ; Female ; Humans ; Infant ; Japanese Encephalitis Vaccines/*immunology ; Male ; Prospective Studies ; Vaccination ; Vaccines, Attenuated/*immunology

Antibodies, Neutralizing ; Antibodies, Viral/isolation & purification* ; B-Lymphocytes/virology* ; COVID-19/virology* ; Humans ; Immunity/genetics* ; RNA, Viral/immunology* ; SARS-CoV-2/pathogenicity* ; Single-Cell Analysis

BACKGROUND: Validation of hemagglutination inhibition (HI) assays is important for evaluating antibody responses to influenza virus, and selection of erythrocytes for use in these assays is important. This study aimed to determine the correlation between receptor binding specificity and effectiveness of the HI assay for detecting antibody response to pandemic influenza H1N1 (pH1N1) virus. METHODS: Hemagglutination (HA) tests were performed using erythrocytes from 6 species. Subsequently, 8 hemagglutinating units of pH1N1 from each species were titrated by real-time reverse transcription-PCR. To investigate the effect of erythrocyte binding preference on HI antibody titers, comparisons of HI with microneutralization (MN) assays were performed. RESULTS: Goose erythrocytes showed most specific binding with pH1N1, while HA titers using human erythrocytes were comparable to those using turkey erythrocytes. The erythrocyte binding efficiency was shown to have an impact on antibody detection. Comparing MN titers, HI titers using turkey erythrocytes yielded the most accurate results, while those using goose erythrocytes produced the highest geometric mean titer. Human blood group O erythrocytes lacking a specific antibody yielded results most comparable to those obtained using turkey erythrocytes. Further, pre-existing antibody to pH1N1 and different erythrocyte species can distort HI assay results. CONCLUSIONS: HI assay, using turkey and human erythrocytes, yielded the most comparable and applicable results for pH1N1 than those by MN assay, and using goose erythrocytes may lead to overestimated titers. Selection of appropriate erythrocyte species for HI assay allows construction of a more reliable database, which is essential for further investigations and control of virus epidemics.
Adult ; Animals ; Antibodies, Neutralizing/immunology ; Antibodies, Viral/*analysis/immunology ; Chickens ; Erythrocytes/*metabolism ; Female ; Geese ; *Hemagglutination Inhibition Tests ; Horses ; Humans ; Influenza A Virus, H1N1 Subtype/genetics/immunology/*metabolism ; Influenza, Human/epidemiology/immunology/virology ; Male ; Middle Aged ; Neutralization Tests ; Pandemics ; Swine ; Turkeys

To develop a specific, rapid, and convenient immunochromatography assay (ICA) to detect the rabies antibody in clinical sample from immuned dogs by rabies vaccine. Colloidal gold particles labeled with purified rabies virus (CVS11) were used as the detector reagent. The staphylococcal protein A (SPA) and pured rabbit anti-rabies virus IgG were blotted on the test and control regions of nitrocellulose membrane. Then the strip was assembled with sample pad, absorbing pad, and dorsal shield. The assay samples (261 dog's serum) were collected from Wildlife Rabies Disease Diagnostic Laboratories of Ministry of Agriculture in China, Institute of Military Veterinary, Academy of Military Medical Sciences and other six provinces, including rabies virus positive and negative serum. The performance of the strip was compared to fluorescent antibody virus neutralization test. The neutralizing antibody titer could be detected above 0.5 IU. The strip did not change of performance when stored at room temperature for 12 months. It may offer reference of neutralizing antibody titer level after dogs immuned rabies vaccine and determin whether the dogs need to be immuned again.
Animals ; Antibodies, Neutralizing ; analysis ; blood ; Antibodies, Viral ; analysis ; blood ; Dogs ; Gold Colloid ; Immunochromatography ; methods ; Rabies ; prevention & control ; veterinary ; Rabies Vaccines ; immunology ; Rabies virus ; immunology ; Reagent Strips ; Sensitivity and Specificity ; Vaccination

OBJECTIVETo ascertain the pathogen of aseptic encephalitis epidemic in Long-Yan city in Fujian, and to find out the genetic characteristics of the virus.

METHODSRapid detection of enteroviral RNA by reverse transcription polymerasechain reaction (RT-PCR) was directly carried out in cerebrospinal fluid(CSF) to isolate and identify the viruses from CSF at the same time, and to detect the neutralization antibody in two serum specimens collected in acute and convalescence phase. Nucleotides of VP1 region was also analyzed by constructing phylogenetic tree.

RESULTSECHO 19 infection was rapidly diagnosed and sequence analysed by RT-PCR, and then echovirus type 19 from 16 of 30 CSF samples (53.33%) was isolated and detected using RD and Hep-2 cells simultaneity. The titer of ECHO 19 neutralization antibody became positive or increased by 4 times from acute to convalescence phase in 4 of the 5 patients. Phylogenetic analyses of the VP1 genes of these isolates showed that their nucleotides identity were 98.9% -100.0% which were different from those ECHO 19 from GeneBank database by 13.0%-22.4%.

CONCLUSIONThe etiology of the epidemic of aseptic encephalitis was attributed to ECHO 19. The method of molecular identification not only provided rapid diagnosis of enterovirus infections, but also information about the genetic character of the viruses.

Antibodies, Neutralizing ; analysis ; China ; epidemiology ; Echovirus Infections ; diagnosis ; immunology ; virology ; Encephalitis, Viral ; epidemiology ; virology ; Enterovirus B, Human ; genetics ; isolation & purification ; Humans ; Phylogeny ; Reverse Transcriptase Polymerase Chain Reaction