Immune protection of auxiliary liver to other allograft: report of 3 cases

OBJECTIVE: To assess the immune status of auxiliary liver transplantation and to clarify the immune protection of auxiliary liver to other allograft. METHODS: Immunological markers and pathological changes in 3 patients undergoing auxiliary liver transplantation were analysed. RESULTS: The lower the concentration of immunosuppressive agent, the less the rejection and the milder the intensity in the 3 patients. The function of allograft after auxiliary liver transplantation was excellent. CONCLUSIONS: Patients are in a low immune reaction state after auxiliary liver transplantation. Auxiliary liver can protect other allografts by related immunological mechanisms. The side-effects of low-concentration immunosuppressive agents on auxiliary liver and other allografts are mild.

New progress of novel COVID-19 variants and its effect on vaccine immune protection

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)poses a serious threat to human life and health as well as social and economic development.In order to deal with this public health event,scientific research institutions around the world have rapidly developed and put vaccines into urgent use,bringing hope to the victory over the epidemic.However,as the Novel Coronavirus continues to spread throughout the world,the virus genome has mutated to form a variety of variants.Among them,the Alpha,Beta,Gamma,Delta and Omicron variants show higher infectivity and higher resistance to vaccines and neutralizing antibodies,posing new challenges to the prevention and treatment of COVID-19.At present,the effect of variants on the effectiveness of developed vaccines has become a hot topic of global discussion.In this paper,we briefly review the new progress of novel Coronavirus variants and their effects on vaccine immune protection.

In vivo anti-tumor effect of hybrid vaccine of dendritic cells and esophageal carcinoma cells on esophageal carcinoma cell line 109 in mice with severe combined immune deficiency

AIM： To develop a fusion vaccine of esophageal carcinoma cells and dendritic cells （DC） and observe its protective and therapeutic effect against esophageal carcinoma cell line 109 （EC109）. METHODS： The fusion vaccine was produced by fusing traditional polyethyleneglycol （PEG）, inducing cytokine, sorting CD34＋ magnetic microbead marker and magnetic cell system （MACS）. The liver, spleen and lung were pathologically tested after injection of the fusion vaccine. To study the therapeutic and protective effect of the fusion vaccine against tumor EC109, mice were divided immune group and therapeutic group. The immune group was divided into P, E, D and ED subgroups, immunized by phosphate buffered solution （PBS）, inactivated EC109, DC and the fusion vaccine respectively, and attacked by EC109 cells. The tumor size, weight, latent period and mouse survival period were recorded and statistically analyzed. The therapeutic group was divided into four subgroups： P, inactivated EC109, D and ED subgroups, which were attacked by EC109 and then treated with PBS, inactivated EC109, DC, and EC109-DC respectively. Pathology and flow cytometry were also used to study the therapeutic effect of the fusion vaccine against EC109 cells.RESULTS： Flow cytometry showed that the expression of folate receptor （FR）, EC109 （C）, Des （D） in human nasopharyngeal carcinoma cell line （HNE1） （B） was 78.21%, 89.50%, and 0.18%, respectively. The fusion cells （C） were highly expressed. No tumor was found in the spleen, lung and liver after injection of the fusion vaccine. Human IgG was tested in peripheral blood lymphocytes （PBL）. In the immune group, the latent period was longer in EC109-DC subgroup than in other subgroups, while the tumor size and weight were also smaller than those in ED subgroup. In the therapeutic group, the tumor size and weight were smaller in ED subgroup than in P, inactivated EC109 and DC subgroups. CONCLUSION： Fusion cells are highly expressed not only in FR but also in CD80. The fusion vaccine has a distinctive protective effect against tumor EC109 and can inhibit the growth of tumor in mice, and its immune protection against tumor attack is more significant.

Construction of Salmonella Pullorum ghost by co-expression of lysis gene E and the antimicrobial peptide SMAP29 and evaluation of its immune efficacy in specific-pathogen-free chicks

In this study, a safety enhanced Salmonella Pullorum （S. Pullorum） ghost was constructed using an antimicrobial peptide gene, and evaluated for its potential as a Pullorum disease （PD） vaccine candidate. The antimicrobial peptide SMAP29 was co-expressed with lysis gene E to generate S. Pullorum ghosts. No viable bacteria were detectable either in the fermentation culture after induction of gene E- and SMAP29-mediated lysis for 24 h or in the lyophilized ghost products. Specific-pathogen- free （SPF） chicks were intraperitoneally immunized with ghosts at day 7 of age and no mortality, clinical symptoms or signs of PD such as anorexia, depression and diarrhea were observed. On challenge with a virulent S. Pullorum strain at 4 wk post-immunization, a comparatively higher level of protection was observed in the S. Pullorum ghost immunized chickens with a minimum of pathological lesions and bacterial loads compared to the birds in inactivated vaccine groups. In addition, immunization with the S. Pullorum ghosts induced a potent systemic IgG response and was associated with significantly increased levels of cytokine IFN-y and IL-4 and relative percentages of CD4＋ and CD8＋ T lymphocytes. Our results indicate that SMAP29 can be employed as a new secondary lethal protein to enhance the safety of bacterial ghosts, and to prepare a non-living bacterial vaccine candidate that can prevent PD in chickens.

Insights into the protective role of immunity in neurodegenerative disease

The immune system（IS）is set to provide protection against pathogens,surveillance against tumor cells and promotion of healing.Such functions can be efficiently performed thanks to the presence of a large network of cells with variable degrees of specialization.

Phage displaying peptides mimic schistosoma antigenic epitopes selected by rat natural antibodies and protective immunity induced by their immunization in mice

AIM: To obtain the short peptides mimic antigenic epitopes selected by rat natural antibodies to schistosomes, and to explore their immunoprotection against schistosomiasis in mice.METHODS: Adults worm antigens (AWA) were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and enzyme-linked transferred immunoblotting methods with normal SD rat sera (NRS). The killing effects on schistosomula with fresh and heat-inactivated sera from SD rats were observed. Then the purified IgG from sera of SD rats was used to biopan a phage random peptide library and 20 randomly selected positive clones were detected by ELISA and 2 of them were sequenced.Sixty female mice were immunized thrice with positive phage clones (0, 2nd, 4th wk). Each mouse was challenged with 40 cercariae, and all mice were killed 42 d after challenge. The worms and the liver eggs were counted. RESULTS: NRS could specifically react to the molecules of 75 000, 47 000, 34 500 and 23 000 of AWA. Sera from SD rats showed that the mortality rate of schistosomula was 76.2%, and when the sera were heat-inactivated in vitro, the mortality rate was decreased to 41.0% after being cultured for 48 h. The specific phages bound to IgG were enriched about 300-folds after three rounds of biopanning. Twenty clones were detected by ELISA, 19 of them bound to the specific IgG of rat sera. Immunization with these epitopes was carried out in mice. Compared with the control groups, the mixture of two mimic peptides could induce 34.9% (P = 0.000) worm reduction and 67.6% (P = 0.000) total liver egg reduction in mice. Two different mimic peptides could respectively induce 31.0% (P = 0.001), 14.5% (P = 0.074) worm reduction and 61.2% (P = 0.000), 35.7% (P = 0.000) total liver egg reduction. The specific antibody could be induced by immunization of the mimic peptides, and the antibody titer in immunized mice reached more than 1:6 400 as detected by ELISA.CONCLUSION: Specific peptides mimic antigenic molecules can be obtained by biopanning the phage random peptide library and a partially protective immunity against schistosome infection can be stimulated by these phage epitopes in mice.

Eukaryocytic Expression of Human B7. 1 （CD80） and its Antileukemia Effect

Objective: To construct the human B7. 1 (CD80) eukaryocytic expressing vector and its expression on HL60 cells to investigate the immunotherapeutic and immunoprotective effects of B7. 1 molecule on acute leukemia. Methods: ①B7. 1 gene was subcloned from the cloning vector using PCR. Both of tlie PCR products and eukaryocytic expressing vector pHook were digested with Apa I , Sal 1 and linked using T4 DNA ligase. Tlie ligased products were transduced into DH5a. B7. 1 gene containing clones were selected by digestion with Apa I and Sal I which were further conformed by sequencing. ②HL60 cells were transformed by B7. 1 with lipofectamine and detected by FACS. ③Tumor formation, mice survival time and the immunotherapeutic and immunoprotective effects by immunization with B7. 1+ cells were evaluated. Results: ①The PCR products were about 620 bp. Six clones were all digested by Apa I and Sal I to produce 620 bp gene fragment which was in tlie same way as 67. 1. It demonstrated t/iat t/ie recombinant vector had been constructed successfully. Further sequencing confirmed the validity of the construction. There was no nucleotide mutation. ② B7. 1 was availably expressed on HL60 cells. ③ B7. 1+ HL60 cells delayed the growth of tumor and prolonged the survival time of leukemic mice, distinctively. So did tlie immunoprotection of B7. 1 + HL60 cells. Conclusion: The human B7. 1(CD80) eukaryocytic expressing vector can be successfully constructed by molecular cloned methods and can be stably and availably expressed on tlie membrane of B7. 1 negative acute myelocytic leukemia (AML) cell line HL60. Furthermore, the costimulatory molecular vaccine has significant effection of immunotherapy and immunoprotection and gives the rationale for clinical application.

Seeking "protective" and "harmful" immune genes during chronic HIV-1 infection by transcriptome analysis

Human immunodeficiency virus(HIV)-infected individuals exhibit remarkable transcriptomic variation.Transcriptome analyses of antiretroviral therapy(ART)-free chronically infected HIV-1 patients with different clinical outcomes are likely to aid the development of vaccine and immune therapies.Here,we performed microarray analyses on whole-blood derived RNA from 89 ART-free HIV-1-infected individuals from 2 cohorts.The differentially expressed genes were analyzed between long-term non-progressors,viremic non-progressors and typical progressors,and between elite controllers and non-elite controllers among the long-term nonprogressors.Several genes related to T-cell growth,proliferation and differentiation and antiapoptosis were upregulated,whereas interferon-stimulated genes and inflammatory genes were significantly downregulated in long-term non-progressors and viremic non-progressors.The observations above were further confirmed in the set of 261 genes that correlated with disease progression during a 5-year follow-up,which included 51 genes significantly associated with slower disease progression,and 210 genes associated with aggressive disease progression.Overall,our data suggest that it is vital to maintain the homeostasis of the immune system when mounting antiviral immune responses.Immune therapeutics able to reconstruct immune homeostasis are likely to be required for immune reconstitution in the context of ART,such as the administration of interleukin-7,healthy allogenic CD4^(+)T cells(providing CD4^(+)T-cell growth factors),or Tregs.

HIV Vaccine-Challenges and Opportunities

The need for an efficacious HIV/AIDS vaccine remains the highest priority of the world HIV/AIDS agenda. The generation of an efficacious HIV/AIDS vaccine proves an enormous scientific challenge. This article reviews the neutralizing antibody problem,elusive immune protection,im-munogen design,pre-existing anti-vector immunity and design of phase 3 vaccine trials and the challenges and opportunities in development of HIV/AIDS vaccine are discussed.

The replicase protein nsp2 of Chinese highly pathogenic porcine reproductive and respiratory virus is involved in protective immunity by promoting viral clearance

The genome segment for replicase protein nsp2 represents the fastest evolving region of porcine reproductive and respiratory syndrome virus(PRRSV),and our previous studies have shown that the PRRSV nsp2 genetic variation contributes to poor cross-neutralization.By using in vitro antibody absorption assay,here we show that the papainlike protease 2(PLP2)domain of nsp2 is a target of neutralizing antibodies.This was further verified by cross-neutralization assay with a series of inter-lineage chimeric mutants between the Chinese highly pathogenic PRRSV(HP-PRRSV)strain JXwn06 and the low virulent NADC30-like strain CHsx1401(lineage 1).The role of nsp2 in protective immunity was subsequently tested in a one-month SPF piglet model by immunizing the piglets with CHsx1401 or its derivatives carrying JXwn06 structural protein region(SP)alone(CHsx1401-SPJX)or in combination with PLP2 region(CHsx1401-SPplp2JX),or the whole nsp2 region(CHsx1401-SPnsp2JX),followed by challenge with JXwn06 at 42 days post immunization,a time point when the viremia was undetectable.All chimera groups were protected from the challenge by JXwn06,whereas the group CHsx1401 failed to provide beneficial protection.Interestingly,the group CHsx1401-SPnsp2JX,but not CHsx1401-SPplp2JX,showed the lowest lung microscopic lesions and viral tissue load.Significantly,the vaccine virus CHsx1401-SPnsp2JX was undetectable in the examined tissues,and so was for the challenge virus except for one piglet,highlighting an important role of HP-PRRSV nsp2 in promoting viral clearance.The findings provide insight into the mechanisms underlying the protective immunity against PRRSV and have important implications in PRRSV vaccine development.

Trichosanthin enhances anti-tumor immune response in a murine Lewis lung cancer model by boosting the interaction between TSLC1 and CRTAM

Trichosanthin(TCS),extracted from the Chinese medicinal herb Trichosanthes kirilowi,has shown promise for the inhibition of tumor growth.However,its immunomodulatory effect on tumor–host interaction remains unknown.In this study,we focused on the effect of TCS on murine anti-tumor immune response in the 3LL Lewis lung carcinoma tumor model and explored the possible molecular pathways involved.In addition to inhibiting cell proliferation and inducing apoptosis in the 3LL tumor,TCS retarded tumor growth and prolonged mouse survival more significantly in C57BL/6 immunocompetent mice than in nude mice.This reflected the fact that the host immune system was involved in tumor eradication.Using FACS analysis,we found that TCS increased the percentage of effector T cells,particularly Interferon-gamma(IFN-c)producing CD41 and CD81 T cells from tumor-bearing mice.TCS also promoted the vigorous proliferation of antigen-specific effector T cells,markedly increased Th1 cytokine secretion and elicited more memory T cells in tumor-bearing mice,consequently enhancing the anti-tumor response and inducing immune protection.Furthermore,we found that TCS upregulated the expression of tumor suppressor in lung cancer 1(TSLC1)in 3LL tumor cells and the expression of its ligand,class I-restricted T cell-associated molecule(CRTAM),in effector T cells.Blocking TSLC1 expression with small interfering RNA(siRNA)significantly eliminated the effects of TCS on the proliferation and cytokine secretion of effector T cells,suggesting that TCS enhances anti-tumor immune response at least partially by boosting the interaction between TSLC1 and CRTAM.Collectively,our data demonstrate that TCS not only affects tumor cells directly,but also enhances anti-tumor immunity via the interaction between TSLC1 and CRTAM.These findings may lead to the development of a novel approach for tumor regression.

Protective Effect of Neonatal Hepatitis B Vaccine Against HBV Breakthrough Infection in Children with Leukemia:A Real-world Study

Background and Aims:Hepatitis B vaccine is the most effective preventive measure against hepatitis B virus(HBV)infection.However,the risk of HBV breakthrough infection in fully immunized children(neonatal hepatitis B immunization)who receive immunosuppressive therapy and transfusion of blood components is not well characterized.In this real-world study,we aimed to investigate the immune protection conferred by neonatal hepatitis B vaccine in children with acute lymphoblastic leukemia(ALL)who were treated with immunosuppressive therapy and blood component transfusions.Methods:Children with ALL who had received all three doses of neonatal hepatitis B vaccine were included in this study.HBV seromarkers were detected before and after the initiation of immunosuppressive therapy.Results:A total of 1,011 children with ALL who were fully vaccinated against hepatitis B in infancy before the initiation of immunosuppressive therapy were eligible for inclusion.HBV infection was detected in four of 410 children(0.98%)with an HBsAg test after the initiation of immunosuppressive therapy.The median interval from treatment initiation was 19 months.Conclusions:Three doses of neonatal hepatitis B vaccine conferred adequate protection.In endemic regions,there is a low risk of HBV breakthrough infection in fully immunized children with immunosuppressive therapy.

Immunomodulation and liver protection of Yinchenhao decoction against concanavalin A-induced chronic liver injury in mice

OBJECTIVE：This study investigated the immunoregulatory and protective roles of Yinchenhao decoction,a compound of Chinese herbal medicine,in a mouse model of concanavalin A（Con A）-induced chronic liver injury.METHODS：Female Bal B/c mice were randomly divided into 4 groups：normal control,Con A model,Con A model treated with Yinchenhao decoction（400 mg/kg,orally）,and Con A model treated with dexamethasone（0.5 mg/kg,orally）.All treatments were given once a day for 28 d.Except of the normal control,mice received tail vein injection of Con A（10 mg/kg）on days 7,14,21,and 28,at 1 h after treatment with Yinchenhao decoction or dexamethasone or saline to induce chronic liver injury.RESULTS：Repeated Con A injection induced chronic liver injury,which was evidenced by infl ammatory cell infi ltration and necrosis,increased serum alanine aminotranferease activities,decreased albumin levels,and an imbalanced expression of immunoregulatory genes in the liver tissues including signifi cantly enhanced interferon-γ,interleukin-4,monocyte chemotactic protein-1,and cluster of differentiation 163 m RNA levels,and reduced tumor necrosis factor-αand interleukin-6 m RNA levels.Treatment with Yinchenhao decoction signifi cantly reversed the Con A-induced changes in immunoregulatory gene expression in the liver tissues,reduced serum alanine aminotranferease activity,enhanced serum albumin level,and attenuated the extent of liver infl ammation and necrosis.Furthermore,Yinchenhao decoction did not result in hepatocyte degeneration and spleen weight loss that were observed in mice received long-term treatment with dexamethasone.CONCLUSION：Yinchenhao decoction treatment protected liver against the Con A-induced chronic liver damage and improved liver function,which were associated with the modulation of gene expression related to immune/infl ammatory response.

Th1 cytokines, true functional signatures for protective immunity against TB?

The lack of an effective preventative vaccine against tuberculosis(TB)presents a great challenge to TB control.Since it takes an extremely long time to accurately determine the protective efficacy of TB vaccines,there is a great need to identify the surrogate signatures of protection to facilitate vaccine development.Unfortunately,antigen-specific Th1 cytokines that are currently used to evaluate the protective efficacy of the TB vaccine,do not align with the protection and failure of TB vaccine candidates in clinical trials.In this review,we discuss the limitation of current Th1 cytokines as surrogates of protection and address the potential elements that should be considered to finalize the true functional signatures of protective immunity against TB.

Priming with FLO8-deficient Candida albicans induces Th1-biased protective immunity against lethal polymicrobial sepsis

The morphological switch between yeast and hyphae of Candida albicans is essential for its interaction with the host defense system.However,the lack of understanding of host-pathogen interactions during C.albicans infection greatly hampers the development of effective immunotherapies.Here,we found that priming with the C.albicans FLO8-deficient(flo8)mutant,locked in yeast form,protected mice from subsequent lethal C.albicans infection.Deficiency of Dectin-2,a fungus-derivedα-mannan recognition receptor,completely blocked flo8 mutant-induced protection.Mechanistically,the flo8 mutant-induced Dectin-2/CARD9-mediated IL-10 production in DCs and macrophages to block thymus atrophy by inhibiting the C.albicans-induced apoptosis of thymic T cells,which facilitated the continuous output of naive T cells from the thymus to the spleen.Continuous recruitment of naive T cells to the spleen enhanced Th1-biased antifungal immune responses.Consequently,depletion of CD4^(+)T cells or blockade of IL-10 receptor function using specific antibodies in mice completely blocked the protective effects of flo8 mutant priming against C.albicans infection.Moreover,mannans exposed on the surface of the flo8 mutant were responsible for eliciting protective immunity by inhibiting the C.albicans-induced apoptosis of thymic T cells to sustain the number of naive T cells in the spleen.Importantly,priming with the flo8 mutant extensively protected mice from polymicrobial infection caused by cecal ligation and puncture(CLP)by enhancing Th1-biased immune responses.Together,our findings imply that targeting FLO8 in C.albicans elicits protective immune responses against polymicrobial infections and that mannans extracted from the flo8 mutant are potential immunotherapeutic candidate(s)for controlling infectious diseases.

DNA vaccine pCD-Sj32 and its efficacy of protective immunity against infection of Schistosoma japonicum

Objective To study protective immunity afforded by murine immunization with DNA vaccine of Schistosoma japonicum (S. japonicum) as measured by reduction in worm burden and host antibody, cytokines.Methods DNA vaccine pCD Sj32 was constructed. identificated and expressed. pCD Sj32 could induce substantial protective immunity against infection of S. japonicum in BALB/c mice. The best efficacy can be produced with one injection of 100?μg DNA into the quadriceps muscle, combined with challenge for 8 weeks after immunization. T lymphocyte subsets of CD 8 +, IL 2. TNF and IFN γ of experimental animal could play important roles in regulating immune functions of schistosomiasis. Results High titre of specific antibody IgG could be induced by vaccinated with pCD Sj32, and antibody can mediate macrophage to produce ADCC effects in vitro. Conclusion pCD Sj32 may represent a new approach to developing subunit vaccine.

Protective immunity against Rickettsia heilongjiangensis in a C3H/HeN mouse model mediated by outer membrane protein B-pulsed dendritic cells

Rickettsia heilongjiangensis is an obligate intracellular bacterium that causes Far-Eastern tick-borne spotted fever. Outer membrane protein B(Omp B) is an important surface protein antigen of rickettsiae. In the present study, the omp B gene of R. heilongjiangensis was divided into four fragments, resulting in four recombinant proteins(OmpB-p1, Omp B-p2, Omp B-p3, and Omp B-p4). Each Omp B was used in vitro to stimulate murine bone marrow-derived dendritic cells(BMDCs) of C3H/He N mice, and the Omp B-pulsed BMDCs were transferred to naive C3H/He N mice. On day 14 post-transfer of BMDCs, the mice were challenged with R. heilongjiangensis and the rickettsial loads in the mice were quantitatively determined on day 7 post-challenge. Mice receiving BMDCs pulsed with Omp B-p2, Omp B-p3, or Omp B-p4 exhibited significantly lower bacterial load compared with mice receiving Omp B-p1-pulsed BMDCs. CD4+ and CD8+ T cells isolated from the spleen of C3H/He N mice receiving BMDCs pulsed with each OmpB were co-cultured with BMDCs pulsed with the respective cognate protein. In flow cytometric analysis, the expression level of CD69 on CD4+ or CD8+ T cells from mice receiving BMDCs pulsed with Omp B-p2, OmpB-p3, or Omp B-p4 was higher than that on cells from mice receiving Omp B-p1-pulsed BMDCs, while the expression level of tumor necrosis factor(TNF)-α on CD8+ T cells and interferon(IFN)-γ on the CD4+ and CD8+ T cells from mice receiving Omp B-p2,-p3, or-p4 was significantly higher than on cells from mice receiving Omp B-p1-pulsed BMDCs. Our results suggest that the protective Omp Bs could activate CD4+ and CD8+ T cells and drive their differentiation toward CD4+ Th1 and CD8+ Tcl cells, respectively, which produce greater amounts of TNF-α and, in particular, IFN-γ, to enhance rickettsicidal activity of host cells.

Immune responses against Schistosoma japonicum after vaccinating mice with a multivalent DNA vaccine encoding integrated membrane protein Sj23 and cytokine interleukin-12

Background The vaccination of mice with DNA encoding single candidate antigens has failed to induce significant protection against Schistosoma japonicum (S. japonicum) challenge infections In this study, we evaluated the feasibility of using a multivalent DNA vaccine which co expressed S japonicum integral membrane protein Sj23 and murine cytokine IL 12 to induce protective immune responses Methods The plasmid pVIVO2 IL12 Sj23, a eukaryotic expression vector expressing Sj23 and murine IL 12 simultaneously, was constructed, identified, and tested for expression in vitro Its ability to protect against S japonicum challenge infections was analyed according to worm reduction rate and egg reduction rate after vaccination of BALB/c mice The serum levels of specific IgG antibody were determined by enzyme linked immuno sorbent assay (ELISA) and Western blot analysis Using cultured spleen cells, IFN γ and IL 4 post stimulation were quantified by ELISA The phenotypes of splenocyte populations were analyzed by flow cytometry (FCM) Results The plasmid DNA pVIVO2 IL12 Sj23 was proven to express well in vitro by transient transfection of HEK 293 cells Immunization resulted in a worm reduction rate of 45 53% and egg reduction rate of 58 35% ELISA and Western blot analysis indicated that immunized mice generated specific IgG against Sj23 Spleen cells showed significant increases in IFN γ but decreases in IL 4 No significant differences in CD4 + and CD8 + subgroup ratios were observed after the challenges Conclusions The multivalent DNA vaccine pVIVO2 IL12 Sj23 is sufficient to elicit moderate but highly significant levels of protective immunity against challenge infections Cytokine IL 12, as a gene adjuvant, was able to enhance the Th1 responses and, hence, the protective immunity

Evaluation of the Safety and Immune Efficacy of Recombinant Human Respiratory Syncytial Virus Strain Long Live Attenuated Vaccine Candidates

Human respiratory syncytial virus(RSV)infection is the leading cause of lower respiratory tract illness(LRTI),and no vaccine against LRTI has proven to be safe and effective in infants.Our study assessed attenuated recombinant RSVs as vaccine candidates to prevent RSV infection in mice.The constructed recombinant plasmids harbored(5′to 3′)a T7 promoter,hammerhead ribozyme,RSV Long strain antigenomic cDNA with cold-passaged(cp)mutations or cp combined with temperature-sensitive attenuated mutations from the A2 strain(A2cpts)or further combined with SH gene deletion(A2cptsΔSH),HDV ribozyme(δ),and a T7 terminator.These vectors were subsequently co-transfected with four helper plasmids encoding N,P,L,and M2-1 viral proteins into BHK/T7-9 cells,and the recovered viruses were then passaged in Vero cells.The rescued recombinant RSVs(rRSVs)were named rRSV-Long/A2cp,rRSV-Long/A2cpts,and rRSV-Long/A2cptsΔSH,respectively,and stably passaged in vitro,without reversion to wild type(wt)at sites containing introduced mutations or deletion.Although rRSV-Long/A2cpts and rRSV-Long/A2cptsΔSH displayed temperature-sensitive(ts)phenotype in vitro and in vivo,all rRSVs were significantly attenuated in vivo.Furthermore,BALB/c mice immunized with rRSVs produced Th1-biased immune response,resisted wtRSV infection,and were free from enhanced respiratory disease.We showed that the combination ofΔSH with attenuation(att)mutations of cpts contributed to improving att phenotype,efficacy,and gene stability of rRSV.By successfully introducing att mutations and SH gene deletion into the RSV Long parent and producing three rRSV strains,we have laid an important foundation for the development of RSV live attenuated vaccines.

Microparticles released by Listeria monocytogenes-infected macrophages are required for dendritic cell-elicited protective immunity

Interplay between macrophages and dendritic cells in the processing and presentation of bacterial antigens for T-cell immune responses remains poorly understood. Using a Listeria monocytogenes （Lm） infection model, we demonstrate that dendritic cells （DCs） require the support of macrophages to elicit protective immunity against Lm infection. DCs themselves were inefficient at taking up Lm but capable of taking up microparticles （MPs） released by Lm-infected macrophages. These MPs transferred Lm antigens to DCs, allowing DCs to present Lm antigen to effector T cells. MP-mediated Lm antigen transfer required M HC class I participation, since M HC class I deficiency in macrophages resulted in a significant reduction of T-cell activation. Moreover, the vaccination of mice with MPs from Lm-infected macrophages produced strong protective immunity against Lm infection. We here identify an intrinsic antigen transfer program between macrophages and DCs during Lm infection, and emphasize that macrophages also play an essential role in DC-elicited Lm-specific T-cell responses.