[Molecular investigation of a possible case of HIV transmission after a blood transfusion].

OBJECTIVE: A molecular technique based on quasispecies analysis for tracing postexposure HIV transmission was applied in an investigation of a possible case of HIV transmission after blood transfusion. METHODS: Sixteen plasma specimens were collected from 3 HIV infections (T1-T3) involved in a possible HIV transmission chain and 13 HIV/AIDS (C1-C13) controls. The RNAs were extracted and then amplified by RT-PCR, the PCR products were cloned and sequenced.BioEdit 6.0.7 and MEGA 4.0 software were used to analyze gene sequences, calculate gene dispersion ratio and construct phylogenetic tree. RESULTS: The sequences of 13 specimens were successfully obtained.The HIV strains from T1, T2 and T3 were CRF07_BC recombinants, those from 5 out of the 6 controls lived in the same city with T2 and T3 were CRF07_BC recombinants as well, while those from 4 controls living in the same city with T1 were CRF01_AE recombinants. Compared with the clone sequences from T1, the mean gene dispersion ratio of T2 was the least (2.0%), followed by C12 (2.8%) , T3 (2.9%) and others. The phylogenetic tree showed that all clones from T1, T2, T3 and C12 might cluster together,and implied that the direction of HIV transmission was from T3 to T2, and then to T1. CONCLUSION: The results support the possible epidemiological clue that HIV was transmitted from T3 to T2, and then to T1, indicating that molecular epidemiological investigation could provide more direct evidence for tracing postexposure HIV transmission.

[Comparison of three HIV antibody confirmatory assay kits in confirming early HIV infection].

OBJECTIVE: This study was to compare the performance of three HIV antibody confirmatory assay kits in confirming early HIV infection. METHODS: Five HIV antibody-positive plasma specimens were ten-fold serially diluted and then detected by ELISA. The above diluted specimens were detected with the following three HIV antibody confirmatory assay kits to analyze their sensitivity, including Wantai-RIBA (Recombinant immunoblot assay, Beijing Wantai Biological Pharmacy, China), MP-WB (HIV Blot 2.2 WB, MP Biomedicals Asia Pacific Pte. Ltd., Singapore) and INNO-LIA (INNO-LIA(TM) HIV I/II Score, Innogenetics N.V., Belgium), respectively. These kits were further used to detect 48 ELISA-reactive specimens from 11 sets of HIV seroconversion specimens (a total of 48 samples) which were previously detected as HIV antibody-positive by ELISA. RESULTS: When 5 samples were diluted to 100 fold, Wantai-RIBA still can detect them positive. Among the 48 HIV antibody-positive specimens detected with ELISA, the confirmation positive rate for Wantai-RIBA, MP-WB and INNO-LIA were 97.92% (47/48), 81.25% (39/48) and 91.67% (44/48), respectively. There was statistically significant difference between the confirmatory results of Wantai-RIBA and MP-WB (χ(2) = 6.13, P < 0.05), as well as between those of INNO-LIA and MP-WB (χ(2) = 5.48, P < 0.05); however, there was no statistically significant difference between those of Wantai-RIBA and INNO-LIA (χ(2) = 1.33, P > 0.05). For other six HIV seroconversion panels containing indeterminate specimens, the average seroconversion period of time for Wantai-RIBA, MP-WB and INNO-LIA were 0.7, 13.3 and 3.7 days, respectively. CONCLUSION: Compared with MP-WB, Wantai-RIBA and INNO-LIA could reduce the window period to confirm early HIV infection.

[Determination of fumonisin biosynthesis gene and toxicity of Fusarium moniliforme strains isolated in China].

OBJECTIVE: To study the relationship between fumonisin biosynthesis gene and toxicity of Fusarium moniliforme isolated in China. METHODS: The toxigenic gene of 29 Fusarium moniliforme isolated from different provinces and varied food samples were determined. Eighteen fum5-positive strains were selected for biosyhesizing fumonisin and determined by high performance liquid chromatography (HPLC). RESULTS: Twenty-six isolates were identified as fum5 gene positive strains. And all of these strains produced FB(1), FB(2) and FB(3). The amount of FB(1), FB(2) and FB(3) was ranging from 0.41-140.20 mg/kg, 0.06-14.30 mg/kg to 0.30-58.00 mg/kg, except one strain produced a lower level of FB(1) only. It wight be the first report showing a high level fumonisin-producing strain isolated from the sesame sample and identified in the world. The amount of FB(1), FB(2) and FB(3) produced by the isolate was 128.84 mg/kg, 11.80 mg/kg and 14.88 mg/kg. CONCLUSIONS: It should have a close relationship between fumonisins biosynthesis gene and toxicity of Fusarium moniliforme isolated in China. The study demonstrated that strain of Fusarium moniliforme might contaminate the sesame sample and produce a high level of fumonisins.