Human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T lymphocytes (CTLs) play a critical role in the control of HIV-1 infection and replication. HIV-1 evades CTL mediated pressure through viral escape mutations within targeted CTLs epitopes or flanking regions, but this process is usually associated with a viral fitness cost. The mutated epitopes may weaken the level of the original CTL responses, however, the immune system holds potential to mount denovo responses towards those newly emerged epitopes. This article briefly summarizes recent research progress regarding the competition between HIV-1's escape mutations and host CTL responses.
Animals ; HIV Infections ; genetics ; immunology ; HIV-1 ; genetics ; immunology ; physiology ; Histocompatibility Antigens Class I ; genetics ; immunology ; Humans ; Mutation ; T-Lymphocytes, Cytotoxic ; immunology ; virology

Anticoagulants ; therapeutic use ; Coronary Artery Disease ; prevention & control ; Humans

0bjective To determine the immunogenicities of DNA vaccines expressing tat-rev-integrase(c-half)-vif-neffusion genes(TRIVN) derived from prevalent B', B'/C and AE recombinant subtypes of HIV-1 in China. Methods Two DNA vaccines were constructed by inserting the codon optimized tat-revintegrase(c-half)-vif-nef fusion genes derived from B' and B'/C subtype of HIV-1 into mammalian expression vector pSVI. 0. DNA vaccine containing tat-rev-integrase (c-half)-vif-nef fusion gene derived from HIV-1AE2f has been constructed previously. In vitro expression efficiencies of three DNA vaccines were determined by Western blot and their immunogenicities were compared by immunizing female BALB/c mice. IFN-γ ELISPOT assay was used to read out the specific T cell immunity. Results The constructed DNA vaccines were validated by restriction enzyme digestion and DNA sequencing. Western blot assay showed three constructed DNA vaccines could be expressed at a comparable level in vitro. After vaccination, AE-TRIVN mounted T cell immune responses at (948.0 ± 330.0) SFCs/106 splenocytes, followed by the mixed DNA vaccine[ (500.0 ± 155.0) SFCs/106 splenocytes ], RL-TRIVN r[ ( 195. 1 ± 44.0) SFCs/106 splenocytes ]and CN-TRIVN [ (89.5 ± 17.0) SFCs/106 splenocytes]. Interestingly, we observed that single DNA vaccination induced specific T cell responses predominantly targeting Integrase (C-half) and Vif, whereas the mixed DNA could significantly improve T cell responses against Nef. Conclusion AE-TRIVN was the most immunogenic among the three DNA vaccines and the mixed DNA vaccination could change the immunogenic hierarchy of T cell epitopes across the fusion genes vaccine.

Objective To elucidate the influences of epitope competition on the frequency and average intensity of specific T cell response.Methods C57BL/6 mice were immunized with either single epitope DNA vaccines (pSV-gag92 or pSV-env203) or fusion gene DNA vaccine (pSV-gag/env).Gag92and Env203 epitope-specific CD8 T cell responses were analyzed by intracellular cytokine staining assay.Results Gag92-specific IFN-γ+CD8 T cells that were induced by pSV-gag92 accounted for 0.415 00％ ±0.045 88％ of the total CD8 T cells,which was much more than that induced by pSV-gag/env of 0.058 67％ + 0.019 64％.Moreover,the mean fluorescence intensity of Gag92-specific TNF-α-IFN-γ+CD8 T cells (296.70+14.08) elicited by pSV-gag/env was significantly lower than that of Env203-specific TNF-α-IFN-γ+CD8 T cells (818.00+49.34).Conclusion Epitope competition could significantly decrease both the frequency and the average intensity of specific T cell response to subdominant epitopes.

Objective To construct two DNA vaccines encoding Gag-Env fusion protein and Tat-Rev-Integrase(C-half)-Vif-Nef fusion protein derived from the first HIV-1 CRF01_AE isolate(AE2f) in Chi-na and to evaluate the immunogenicity in mice. Methods Two DNA vaccines were constructed by inserting the codon optimized and synthesized gag-env fusion gene and tat-rev-integrase(c-half)-vif-nef fusion gene de-rived from AE2f into mammalian expression vector pDRVISV1. 0, the generated DNA vaccines were desig-nated as pSVAE/GE and pSVAE/TRIVN, respectively, and their in vitro expression were determined by Western blot with transfected 293T cells. Mice were i. m. immunized with either pDRVI1.0 as mock control, pSVAE/GE or pSYAE/TRIVN for 4 times at two-week interval. Two weeks following the final im-munization, cellular responses to pool of HIV-1 Env, Gag, Tat, Rev, Intergrase, Vif and Nef peptides were evaluated by ELISPOT assay. Results The construction of DNA vaccine pSVAE/GE and pSVAE/TRIVN was validated by restriction enzyme digestion and bidirectional sequencing. Western blot showed a specific band at molecular mass 220×10~3 in lane of pSVAE/GE transfeeted 293T cell and a specific band at 95×10~3 in the lane of pSVAE/TRIVN. Both DNA vaccines mounted significant specific T cell responses with (3010 ± 566) SFC/10~6 splenocytes for DNA vaccine pSV AE/GE and (948 ± 737) SFC/10~6 spleno-cytes for DNA vaccine pSVAE/TRIVN, whereas the mock control of pDRVISV1.0 only raised marginal T cell responses. Conclusion Both pSVAE/GE and pSVAE/TRIVN were capable of expressing the inserted fusion immunogen genes and able to elicit vigorous cellular immune responses, therefore, these DNA vac-cines are highly immunogenic.

Objective To investigate and compare the features of the HIV-1-specific CTL responses among three HIV-infected groups with varied infection history. Methods Three HIV-infeeted groups were enrolled in this study, including two groups infected by blood transmission (one group has been infected for more than 10 years and the other for 1-2 years) and one group of the man who have sex with man. The HIV-1-specific CTL responses were quantified by an IFN-γ based ELISPot assay with a peptide matrix system containing overlapping peptides spanning the entire HIV-1 Clade B genomic consensus sequences. Results The responding rate of CTL responses against all 17 peptide pools among the group that infected 1-2 years,the group infected more than 10 years and the group of MSM were 40% ,65% ,23%. One way ANOVO analysis showed that the responding rate of CTL responses against all 17 peptide pools were statistical significant among the three groups (F=19.96, P＜0.01);the magnitude of CTL responses of the three groups were 0-5 835 SFCs/106 PBMC, 0-7 225 SFCs/106PBMC, 0-9 740SFCs/106pBMC, Kruskal-Wallis test showed that the magnitude of CTL responses were statistical significant among the three groups( H = 101.90 , P ＜0.01);the breadth of CTL were 7 ( 2-11 ), 11(9-14) and 4 (2-6) respectively and Kruskal- Wallis test showed that the breadth of CTL had no statistical significant among the three groups( H = 34. 75 ,P ＜0. 01 ). The sequence of responding rate, magnitude and breadth of CTL from high to low was the group that had been infected for more than 10 years, the group infected 1-2 years and the sex transmission group. The common characteristics of the CTL response among the three groups were that the responding rate and the magnitude of the peptide Nef and Gag was higher than other peptide's. The magnitude of CTL responses among three different CD4count groups (CD4 ＜ 200/μl, CD4 200-500/μl, CD4 ≥500/μl,) was 0-18 475 SFCs/106pBMC, 350-34 095 SFCs/106pBMC, 490-21 550 SFCs/106 PBMC and had no statistic difference among the three different CD4 groups(H=2.93, P=0.23) while the breadth of CTL was 3(0-8), 10(2-17), 10 (1-17)respoctively and the breadth of CTL was lower in the group of CD4 count less than 200/μl than the other two groups( H = 14. 72, P ＜ 0. 01 ). The magnitude of CTL responses among three different viral load (VL)groups (VL＜ LDL, LDL ＜ VL ＜ 1 × 104 copys/ml, VL≥1 ×104 copys/ml) was 490-18 475 SFCs/106pBMC, 0-24 115 SFCs/106pBMC, 770-34 095 SFCs/106 pBMC and had no statistic difference among the three different viral load groups ( H = 0.79, P=0.67) and the breadth of the three different viral load groups CTL was 8( 1-17), 11 (0-17), 8 (1-16) and Kruskal-Wallis test showed that there was no statistic difference among the three different viral load groups (H =5.27, P =0. 07). Conclusions All groups predominantly develope T cell immune responses against Nef and Gag proteins. With the elapse of HIV infection, the CTL responses are increased in both magnitude and responding rate. This information is important for vaccine development.

BACKGROUND:Biomechanical compatibility is the necessary condition to ensure the stable osseointegration with implants that then can function over a long period; therefore, it is especialy important to get knowledge about distribution of stress and strain between the maxilary central incisor and its surrounding bone tissue. OBJECTIVE: Based on five different anatomical types of natural teeth, to study the regularity of stress distribution between the maxilary central incisor root and implant.METHODS: According to the five different anatomical types of natural maxilary central incisors, UGNX and ANSYS were used to set up three-dimensional finite element models (B1, B2, M1, M2, P1) for the implant and surrounding structures, which were under 100 N static load at angles of 0o, 30o, 45o, 60o, 90o with the long axis of teeth. Then, the stress distribution between the five kinds of maxilary central incisor roots and implants was analyzed. RESULTS AND CONCLUSION:Among the five different anatomical types, the equivalent stress for both the natural central incisor and implant were increased with the increasing of angles, and the implant had a higher raising trend. The equivalent stress for the natural tooth concentrated upon B1 for the maximum value and M1 for the minimum value; while the equivalent stress for the implant focused on the maximum value at M1 and the minimum value at M2. There was a gap of 2%-31% between the equivalent stresses for the natural tooth roots and a gap of 4%-21% for the implants. The stress distribution range for the implant was just smaler than that for the natural tooth roots. It implies that the bit force of implant and natural tooth is in positive proportion to the bite angles, and the bite force that implant can burden is smaler than that the central incisor can.

Objective:To develop a nursing information system effectiveness evaluation scale based on the new D&M model and verify its reliability and validity.Methods:Six dimensions of the scale were constructed based on the framework of the new D&M model,through the methods including literature reading,expert discussion to determine the specific indicators of the questionnaire, and then forming the initial questionnaire. The dimensions and items of the test scale were modified by discriminant analysis method, correlation coefficient analysis method and Cronbach's αcoefficient method. The construct validity of the scale was analyzed by exploratory factor analysis method, and the dimensions and items of the test scale were optimized. Internal consistency and retest reliability were used to analyze the reliability of the scale.Results:Five common factors were extracted by exploratory factor analysis to explain the total variation of 57.462%. The final version of the scale consists of 5 dimensions and 23 items. The total Cronbachα coefficient of the scale was 0.768, and the total correlation coefficient was 0.849.Conclusions:The 5 dimensions retained by the scale have good construction validity, which can effectively explain the psychological characteristics of the subjects, and the results measured by the scale have good stability and consistency. This scale can be used to evaluate the effectiveness of nursing information system.

Objective To investigate the number and distribution of N-linked glycosylation sites of simian/human immunodeficiency virus envelope proteins (SHIVSF162P3) and SHIV transmission. Methods Two female adult Chinese rhesus macaques (4 years old) were intravenously inoculated with 300 TCID50 SHIVSF162P3. The macaques weighed 4 and 5 kg and were identified as Rh1 and Rh2. We collected plasma samples at days 3, 7, 10, 14, 17, 21, 24, 28, 35, 42, 49, 56, 63, 70 and 77 post-challenge. Subsequently, we monitored plasma viral load by real-time PCR after viral RNA isolation and cDNA synthesis. We amplified the full-length envelope gene by single genome amplification (SGA) at days 7, 14, 28 and 77. BioEdit, MEGA, and the HIV Databases were used to analyze envelope sequences. Sequence diversity and N-linked glycosylation sites were compared between virus stock and plasma viruses of the two macaques. Results A total of 55 env sequences were obtained from virus stock and their average pairwise distances were (0.166 6± 0.096 3)%. Viral loads peaked at 7.68 and 7.49 log10 copies/ml at day 10 and reached the set point at day 42 (4.27 and 4.81 log10 copies/ml). The percentages of envelope sequences containing 25 potential N-linked glycosylation sites (PNGSs) were 83%(20/24) and 94%(29/31) in Rh1 and Rh2, respectively, at day 7;these were significantly higher than the proportion in SHIVSF162P3 stock (49%(27/55)). Viral diversity after infection increased with time whereas the proportion of sequences containing 25 PNGSs decreased and sequences containing 27 PNGSs gradually increased. In Rh1, the percentage of sequences containing 27 PNGSs increased to 29%at day 28 and reached 35%at day 77 in Rh2. By analyzing the number of PNGSs in the V1-V5 regions, we found that PNGS variation mainly occurred in the V4 loop. Compared with sequences containing 27 PNGSs, a seven amino acid (TWNNTIG) deletion was found in the V4 loop, which resulted in a loss of two PNGSs at positions 392 and 396. Conclusion Low glycosylation of the SHIVSF162P3 V4 loop may facilitate spread of the SHIV virus whereas viruses with highly glycosylated V4 loops showed replication advantages after infection.

Objective To investigate the number and distribution of N-linked glycosylation sites of simian/human immunodeficiency virus envelope proteins (SHIVSF162P3) and SHIV transmission. Methods Two female adult Chinese rhesus macaques (4 years old) were intravenously inoculated with 300 TCID50 SHIVSF162P3. The macaques weighed 4 and 5 kg and were identified as Rh1 and Rh2. We collected plasma samples at days 3, 7, 10, 14, 17, 21, 24, 28, 35, 42, 49, 56, 63, 70 and 77 post-challenge. Subsequently, we monitored plasma viral load by real-time PCR after viral RNA isolation and cDNA synthesis. We amplified the full-length envelope gene by single genome amplification (SGA) at days 7, 14, 28 and 77. BioEdit, MEGA, and the HIV Databases were used to analyze envelope sequences. Sequence diversity and N-linked glycosylation sites were compared between virus stock and plasma viruses of the two macaques. Results A total of 55 env sequences were obtained from virus stock and their average pairwise distances were (0.166 6± 0.096 3)%. Viral loads peaked at 7.68 and 7.49 log10 copies/ml at day 10 and reached the set point at day 42 (4.27 and 4.81 log10 copies/ml). The percentages of envelope sequences containing 25 potential N-linked glycosylation sites (PNGSs) were 83%(20/24) and 94%(29/31) in Rh1 and Rh2, respectively, at day 7;these were significantly higher than the proportion in SHIVSF162P3 stock (49%(27/55)). Viral diversity after infection increased with time whereas the proportion of sequences containing 25 PNGSs decreased and sequences containing 27 PNGSs gradually increased. In Rh1, the percentage of sequences containing 27 PNGSs increased to 29%at day 28 and reached 35%at day 77 in Rh2. By analyzing the number of PNGSs in the V1-V5 regions, we found that PNGS variation mainly occurred in the V4 loop. Compared with sequences containing 27 PNGSs, a seven amino acid (TWNNTIG) deletion was found in the V4 loop, which resulted in a loss of two PNGSs at positions 392 and 396. Conclusion Low glycosylation of the SHIVSF162P3 V4 loop may facilitate spread of the SHIV virus whereas viruses with highly glycosylated V4 loops showed replication advantages after infection.