[Evaluation of four kits for screening HIV antibody].

OBJECTIVE: To Evaluate four kits for screening HIV antibody by comparing and analyzing the HIV antibody screening positive results and Western Blot (WB) test results. METHODS: From January 2004 to June 2009, three ELISA kits (Zhongshan, Biomérieux and Livzon) were used for initial screening HIV antibody. The reactive positive samples were reexamed by initial ELISA kit and a rapid kit (Abbot Determine HIV-1/2). All repeatedly reactive positive screening results were followed by WB test. RESULTS: A total of 193 (0.094%) WB confirmed positive results were obtained from 206 151 specimens. The sensitivities and predictive values of negative test result (PVN) of three ELISA kits were all 100% and those of Abbot Determine HIV-1/2 were 93.93%, and 91.67% respectively. All false negative results from Abbot were WB indeterminate. The specificities of Zhongshan, Biomérieux, Livzon and Abbot were 99.88%, 99.89%, 99.96% and 89.38%; the study predictive values of a positive test result (PVP) were 35.58%, 46.46%, 76.61% and 92.20%; the efficiencies were 99.88%, 99.89%, 99.96% and 91.98%; the areas under ROC curve of the three ELISA kits were 0.93, 0.99, and 0.95 respectively. PVP of Livzon was obviously higher than those of Zhongshan (chi(2) = 45.804, P = 0.000), Biomérieux (chi(2) = 25.231, P = 0.000) and Biomérieux was higher than Zhongshan (chi(2) = 2.488, P = 0.115). PVP of Abbot was highest (chi(2) = 18.633, P = 0.000, vs Livzon). There were some specimens with S/CO (optical density of sample/cut off) ratio < 6 or > or = 6 in all three groups with positive, indeterminate and negative WB results. The S/CO ratio from Zhongshan in confirmed positive group (14.29 + or - 2.63) was higher than in positive-negative group (2.80 + or - 3.25) (t = 17.652, P = 0.000). The S/CO ratio from Biomérieux in confirmed positive group(16.09 + or - 2.35) was higher than in positive-negative group (2.14 + or - 1.91) (t = 31.622, P = 0.000). The S/CO ratio from Livzon in confirmed positive group (11.54 + or - 1.95) was higher than in positive-indeterminate group (5.54 + or - 3.57) (t = 6.386, P = 0.000), positive-negative group (3.25 + or - 2.41) (t = 21.772, P = 0.000) and positive-indeterminate group was higher than positive-negative group (t = 2.301, P = 0.033). CONCLUSION: The performances of four HIV antibody screening kits are good but estimating WB confirming result in line with S/CO ratio is not available. All repeated screening positive results should be followed by confirmatory tests.

[Comparison of the reliability of two ELISA kits for detecting IgM antibody against hepatitis E virus].

OBJECTIVE: To study the reliability of two ELISA kits for detecting IgM antibody against hepatitis E virus (HEV). METHODS: Serum samples from 92 healthy subjects, 71 cases suspected of hepatitis E, 55 patients with confirmed diagnosis of acute hepatitis E, 50 individuals with rheumatoid factor (RF) positive and 54 persons with anti-HAV IgM positive were detected with three hepatitis E diagnostic kits. MP-IgM (MP, Singapore), Wantai-IgM and anti-HEV IgG (Wantai, China). HEV RNA was analyzed with RT-PCR in 52 of 71 cases suspected of hepatitis E. RESULTS: In healthy subjects,cases suspected of hepatitis E and confirmed acute hepatitis E, the concordance between the two anti-HEV IgM reagents was 73.39% (160/218) and the significant differences in the positive rates of two assays were not observed [46.79% (102/218) vs 44.04% (96/218), chi2 = 0.62, P > 0.05]. Of 71 patients suspected of hepatitis E, the sensitivity for diagnosing acute hepatitis E of Wantai-IgM and MP-IgM were 83.08% (54/65) and 78.46% (51/65) (chi2 = 0.16, P > 0.05), respectively. Among those suspected of hepatitis E with HEV RNA positive, the sensitivity of Wantai-IgM was obviously higher than that of MP-IgM [(97.14%, 34/35) vs (74.29%, 26/35), chi2 = 4.9, P < 0.05]. 48 of 55 patients (87.27%) with confirmed diagnosis of hepatitis E were Wantai-IgM positive while 37 (67.27%) was MP-IgM positive (chi2 = 4.0, P < 0.05). The specificity of Wantai-IgM was higher than MP-IgM [100.00% (202/202) vs 89. 11% (180/202), chi2 = 20.05, P < 0.005]. RF and anti-HAV IgM might cause MP-IgM false positive without interference on Wantai-IgM. CONCLUSION: Wantai-IgM should be a good ELISA kit for the diagnosis of acute hepatitis E.

[Correlations between preS1-antigen, HBV-DNA and HBV serum markers in patients with chronic hepatitis B].

OBJECTIVE: To study the correlations between preS1 antigen, HBV-DNA and hepatitis B virus (HBV) serum markers in patients with chronic hepatitis B. METHODS: The HBV markers, preS1 antigen and HBV-DNA were determined using enzyme- linked immunosorbent assay and quantitative PCR in 1158 patients with chronic hepatitis B. RESULTS: In these patients, the HBV-DNA positivity rate was 68.9%, significantly higher than preS1 antigen positivity (54.8%, chi2=53.24, P<0.005). The positivity rates of both HBV-DNA and PreS1-antigen were significantly higher in HBeAg-positive patients than in HBeAg-negative patients (P<0.005). The coincident rates of preS1-antigen and HBeAg with HBV-DNA were 56.9% and 63.3%, respectively. PreS1 antigen had higher sensitivity but lower specificity than HBeAg. The detection rates of preS1 antigen and HBeAg increased with the level of HBV-DNA, and preS1 antigen positivity was higher than that of HBeAg in patients with low HBV-DNA levels. CONCLUSION: Detection of HBV serum markers along with preS1 antigen and HBV-DNA may help assess the status of viral replication and therapeutic efficacy in patients with chronic hepatitis B. PreS1 antigen may serve as an auxiliary indicator in HBeAg-negative cases or when HBV-DNA detection is impossible.