Molecular mechanism of resistance to VRC01 neutralization in HIV-1 subtype B′ strains / 中华微生物学和免疫学杂志

Objective:To investigate the molecular mechanism of VRC01 resistance in HIV-1 subtype B′ strains isolated from a patient (DRVI01) with broadly neutralizing antibody (bNAb).Methods:Sequences of the HIV-1 subtype B′ strains isolated from patient DRVI01 were compared with those of HIV-1 subtype B′ strains that were isolated at the same time but sensitive to VRC01 antibody. Key amino acids that might affect the neutralization of VRC01 were selected according to literature reports. Effects of the selected amino acids on VRC01 neutralization were verified by site-directed mutation and sequence exchange of membrane proteins from different patients.Results:Single-point mutations of E279D and R282K in LoopD region and N460A and N463Q in V5 region reversed the viral sensitivity to VRC01 neutralization. Combined mutations in two or three above-mentioned sites significantly increased the viral sensitivity to VRC01 antibody compared with single-point mutations. Contrary to literature reports, the glycosylation site mutation of N276 had no influence on the viral sensitivity to VRC01.Conclusions:HIV-1 subtype B′ strains isolated from patient DRV01 with bNAb carried the mutations of D279 and K282 in LoopD region and N460 and N463 in V5 region, resulting in resistance to VRC01 antibody.

Differential Effects of Lactobacillus casei Strain Shirota on Patients With Constipation Regarding Stool Consistency in China

BACKGROUND/AIMS: Probiotics are expected to confer benefits on patients with constipation, but how probiotics act on constipated patients with variable stool consistencies remains unclear. We investigated the effect of Lactobacillus casei strain Shirota (LcS) on constipation-related symptoms, especially stool consistency, of constipated patients. METHODS: Constipated patients meeting the Rome III criteria were divided into 3 groups according to the Bristol Stool Form Scale (BSFS): hard (hard stool [HS], BSFS < 3), normal (normal stool [NS], ≤ 3 BSFS ≤ 4), and soft (soft stool [SS], 4 < BSFS ≤ 5) stools. Subjects in each group consumed a probiotic beverage containing 1010 colony-forming units of LcS daily for 28 days. RESULTS: LcS intervention significantly alleviated constipation-related symptoms and increased defecation frequency in all subjects. Four weeks of LcS supplementation softened the hard stools in HS, hardened the soft stools in SS, and did not alter the ideal stool consistency in NS. The short-chain fatty acid (SCFA) concentrations were highest in SS, followed by NS and HS. LcS intervention increased the stool SCFA levels in HS but reduced or did not alter the levels in NS and SS. LcS intervention increased the Pseudobutyrivibrio and Roseburia abundances in HS and decreased the Pseudobutyrivibrio abundance in SS. CONCLUSIONS: LcS supplementation improved the constipation-related symptoms in constipated subjects. Differences in baseline stool consistency could result in different anti-constipation effects of LcS intervention. LcS balanced the stool consistency—softened the HS and hardened the SS. These effects could be associated with modulation of the gut microbiota and SCFA production.

Eukaryotic expression and serodiagnostic potential of HIV-1 p24 antigen / 中华微生物学和免疫学杂志

Objective To express HIV-1 capsid p24 antigen in an eukaryotic expression system and to evaluate its antigenicity and potential in the early diagnosis of HIV. Methods The full-length gene of HIV-1 p24 and the signal peptide DRVI gene were amplified by PCR. The signal peptide DRVI preceding the p24 gene was introduced using fusion PCR, and cloned into vector pDRVI1. 0. Two recombinant plas-mids pDRVI-p24 and pDRVI-p24s were constructed and transfected into 293F cells. Expression and secre-tion of p24 protein were detected by SDS-PAGE, Ni-NTA column chromatography and molecular sieve were used to purify p24s protein. The purified protein was identified by Western blot and indirect ELISA using hu-man/mouse HIV-1-positive serum samples. Results The eukaryotic expression system for HIV-1 p24 anti-gen was successfully established with high efficiency. The target protein of interest with the signal peptide DRVI was obviously detected in the supernatants of cell culture. The recombinant protein had good specifici-ty and sensitivity based on the results of serological tests using serum samples of five HIV-1-positive and five HIV-negative mice , 30 HIV-1-positive patients and 50 HIV-1-negative healthy individuals . Conclusions The eukaryotic expression system for HIV-1 p24 antigen was successfully established. The purified HIV-1 p24s antigen had good antigenicity. An indirect ELISA assay with good specificity and sensitivity for the de-tection of HIV-1 was preliminarily constructed and showed great potential for application.

Single B cell sorting-based amplification and functional identification of HIV-1 monoclonal antibody genes / 中华微生物学和免疫学杂志

Objective@#To amplify and identify monoclonal antibody genes from HIV-1-infected patients.@*Methods@#Single cell sorting was used to isolate antigen-specific single B cells. Sequence Identity Matrix and the international ImMunoGeneTics information system were used to analyze antibody variable region genes. Binding abilities were detected by enzyme linked immunosorbent assay. Neutralizing activities were tested by TZM-bl/pseudovirus assay.@*Results@#The heavy and light chain genes of four, seven, and eleven antibodies were amplified and sequenced from three HIV-1-infected patients, respectively. They were derived from various germline genes with flexible CDR3 lengths and somatic mutations. A1 and B3 antibodies bound to HIV-1 clade B, CRF01_AE, and CRF07_BC antigens. The half maximal inhibitory concentration values of A1 and B3 against MW965 virus were 0.04 μg/ml and 37.34 μg/ml.@*Conclusion@#In this study, we acquired a lot of monoclonal antibody genes and two HIV-1 monoclonal binding and neutralizing antibodies, which would provide basic data for further research on monoclonal antibody identification.

Isolation and identification of neutralizing monoclonal antibodies to two Tier 2 viruses in a patient with HIV-1 infection / 中华微生物学和免疫学杂志

Objective To isolate neutralizing monoclonal antibodies to Tier 2 viruses in a Chinese patient with HIV-1 infection. Methods Monoclonal antibodies were isolated using single B cell sorting and monoclonal antibody expression technique. The international ImMunoGeneTics database (IMGT) was used to analyze antibody variable region genes. Antibody binding ability and neutralizing activity were tested by enzyme linked immunosorbent assay and TZM-bl/pseudovirus assay,respectively. Results Two monoclonal antibodies (E11 and H2) that could neutralize two Tier 2 viruses were isolated from the patient with clade B HIV-1 infection. Heavy chains of E11 and H2 were derived from IGHV4-4*08 with a somatic mutation rate of 15.79% and 14.74%,respectively. Light chains were both derived from IGKV3-15*01 with a somatic mutation rate of 8.33% and 7.95%, respectively. E11 and H2 could bind to HIV-1 clade B, CRF01_AE and CRF07_BC viruses. The half maximal inhibitory concentration(IC50) values of E11 and H2 were 18.78 μg/ml and 22.43 μg/ml against 398-F1 virus and 43.35 μg/ml and 39.45 μg/ml against 25710 virus. Conclusion In this study, two neutralizing monoclonal antibodies to two Tier 2 viruses were identified in the patient with HIV-1 infection,which might provide reference for the development of AIDS vaccines.

The humoral immune response in guinea pigs primed with recombinant vaccinia virus strains ex-pressing Transmitted/Founder virus HIV-1 membrane proteins and boosted with gp140 protein / 中华微生物学和免疫学杂志

Objective To analyze the antibody responses in guinea pigs vaccinated with recombi-nant vaccinia virus( rTT) strains expressing transmitted/founder ( T/F) HIV-1 membrane proteins in combi-nation with gp140 protein.Methods Guinea pigs were primed with rTT strains and boosted twice with gp140 protein in every four weeks.Serum samples were collected from guinea pigs before immunization and in 2, 6 and 10 weeks after the last immunization for the detection of HIV-1-specific binding antibodies, neu-tralizingantibodiesandtherelativeavidityofantibodies.Results (1)Thebindingantibodiesspecificto HIV-1 B′/C, B, AE subtypes were efficiently induced by the immunization of rTT-B, rTT-C and rTT-CON vaccinia strains in combination with gp140 protein.The antibody titers ranged from 111 430 to 1 024 000. More antibodies against HIV-1 B′/C and AE subtypes were induced in guinea pigs by the immunization of rTT-C and rTT-CON strains in combination with gp140 protein than those by using rTT-B strain prime-protein boost strategy (P<0.05).No significant differences with the titers of HIV-1 B subtype specific antibody were observed among the guinea pigs immunized with the three strategies.( 2 ) High titers of SF162 and ZM109 neutralizing antibodies were induced in guinea pigs immunized with rTT-B, rTT-C and rTT-CON vac-cinia strains in combination with gp140 protein, ranging from 83.76 to 649.30.No significant differences were found among the three groups.(3) The HIV-1 V1V2-gp70 specific antibodies associated with protec-tive immunity were induced by immunization of the three virus prime-protein boost strategies.No significant differences were observed among them.(4) Antibodies induced in guinea pigs by immunization of the three strategies showed strong affinity to membrane proteins of HIV-1 B′/C, B, AE subtype strains.No significant differences were found among the three immunization strategies.Conclusion A strong humoral immune re-sponse was induced in guinea pigs primed with recombinant vaccinia virus strains expressing T/F virus HIV-1 membrane proteins and boosted with gp140 protein.

Expression, purification and renaturation of Pol P51 antigen of HIV-1 strain CN54 and its application in antibody detection / 生物工程学报

To obtain the pure and soluble P51 antigen of HIV-1 strain CN54, we transformed the Escherichia. coli strain BL21 codonplus-RIL with recombinant plasmid pTHioHisA51 which carries a gene encoding the Polymerase (Pol) P51 antigen of HIV-1 CN54 formerly, and induced protein expression by IPTG. We purified the recombinant protein with Chelating Sepharose FF-Ni and DEAE-Sepharose FF column chromatography, then renatured the recombinant protein by dialyzation. Purified protein was identified by Western blotting. We labeled and coated antigen P51 in a dual-antigen sandwich system, and tested it with serum samples from HIV-infected individuals. The results showed that P51 was expressed as inclusion body, and represented about 50% of total cellular protein. After purification and renaturation, the purity of P51 was up to 95%. Western blotting and sandwich ELISA demonstrated that recombinant P51 had good anti-HIV antibody specificity and sensitivity. The results suggested that recombinant HIV-1 P51 can be prepared as diagnostic reagent, and provides valuable support for HIV-1 detection and vaccine research.

Optimization of induction and purification of HIV-1 Gag protein in Escherichia coli expression system / 生物工程学报

To investigate the effects of induction temperature on the expression product and the impact of urea concentration on the purification, HIV-1 Gag inclusion bodies from E. coli induced at 30 degrees C (IB30) and 37 degrees C (IB37) were dissolved with urea of different concentrations. The solubility and yield of refolding were compared. IB30 were dissolved with 2 mol/L and 8 mol/L urea, and then purified with chromatography. IB30 were found easier to be solubilized in low concentration of urea and easier to be refolded than IB37. Furthermore, compared to the IB30 dissolved in 8 mol/L urea, Gag protein solubilized in 2 mol/L urea was purified to higher purity with gel filtration (GF) and ion exchange (IEX) chromatography. Gag inclusion body induced at lower temperature may contain more protein with native-like or reversibly-denatured structures, and solubilization in the presence of low concentrations of urea can help to retain these structures. This study has provided new insights into the purification of proteins from inclusion bodies.