Host defenses in murine malaria: analysis of the mechanisms of immunity to Plasmodium berghei generated in response to immunization with formalin-killed blood-stage parasites.

Syngeneic B6D2F1 (C57Bl/6 x DBA/2) mice were immunized with a nonliving antigen prepared from mixed blood forms of Plasmodium berghei strain NYU-2. Consistently greater than 80% of the vaccinated mice survived virulent challenge, and protective immunity was demonstrable from 1 week through at least 4 months after immunization. However, vaccination did not prevent the development of patient infection after challenge. Instead, infections in vaccinated mice progressed to about 10% parasitemia and were then subsequently cleared. In contrast, infections initiated in nonvaccinated mice progressed beyond 10% parasitemia and were uniformly fatal within 4 weeks. Sera collected from normal mice, nonvaccinated mice infected with P. berghei, or vaccinated mice before challenge failed to passively protect recipients against virulent infection. On the other hand, sera collected from vaccinated mice after recovery from a challenge infection conferred upon passively immunized recipients protection from homologous virulent challenge, which was manifest as a delay in the onset of overt infection. It was concluded, therefore, that vaccination altered the immunological potential of the host in such a way as to allow the production of a protective humoral factor, probably specific antibody, in response to infection with the virulent parasites.     

Host defenses in murine malaria: nonspecific resistance to Plasmodium berghei generated in response to Mycobacterium bovis infection or Corynebacterium parvum stimulation.

Infection with Mycobacterium bovis (BCG) or injection of killed Corynebacterium parvum protected some strain B6D2 F1 (C57BL/6xDBA/2) mice but did not protect strain ICR or A mice from lethal challenge with Plasmodium berghei strain NYU-2. B6D2 mice were not protected against challenges delivered immediately after intravenous injection of these materials, but rather protection developed by day 7 and persisted through at least day 84. Infections in protected mice progressed to about 10% parasitemia in parallel with infections initiated with the same inoculum in untreated controls. However, infections in most of the protected mice were cleared subsequently, whereas infections in untreated controls were uniformly fatal. A small number of treated mice developed protracted high-level erythrocytic infections, which led to markedly delayed death. BCG-infected mice which survived P. berghei infections had a factor in their sera which protected passively immunized recipients from P. berghei. BCG-infected mice passively immunized with protective serum controlled P. berghei infections better than normal mice given the same amount of the same serum and challenged with the same P. berghei inoculum. The capacity of BCG-infected B6D2 mice to resist P. berghei infection was not directly related to the pattern of growth of BCG, to the degree of splenomegaly, or to the level of activation of macrophages (measured as microbicidal capacity) caused by BCG infection. Therefore, I concluded that (i) BCG infection or injection of killed C. parvum altered the immunological potential of B6D2 mice in such a way as to allow the production of measurable levels of a protective humoral factor in response to infection with P. berghei; (ii) BCG infection caused the generation of a capacity which, when expressed in the presence of immune serum, provided an anti-P. berghei capacity which was superior to that provided by BCG infection alone or immune serum in the absence of BCG infection; and (iii) not all strains of mice could be protected from P. berghei by BCG or C. parvum injection.     

Glucan-enhanced immunogenicity of killed erythrocyte stages of Plasmodium berghei.

Intravenous injections of glucan simultaneously with Formalin-killed erythrocytic stages of Plasmodium berghei elicited a greater degree of resistance in mice against subsequent infection with viable parasites than injections of killed erythrocytic stages alone. In two experiments with P. berghei strain NK 65, 100% of mice immunized with the glucan-dead parasite preparation survived challenge, whereas only 28.6% of mice receiving dead parasites alone survived. In the third experiment, using P. berghei strain NYU-2, the same proportion of mice survived after immunization with glucan and dead parasites as with dead parasites alone (i.e., 10 of 11 in each group), but mice immunized with the glucan-dead parasite preparation experienced parasitemias of significantly less intensity and shorter duration than mice which received only dead parasites before infection. Inoculation of glucan alone or with normal erythrocytes conferred no protection against challenge.     

Subcutaneous vaccination with attenuated Salmonella enterica serovar Choleraesuis C500 expressing recombinant filamentous hemagglutinin and pertactin antigens protects mice against fatal infections with both S. enterica serovar Choleraesuis and Bordetella bronchiseptica

Salmonella enterica serovar Choleraesuis strain C500 is a live, attenuated vaccine that has been used in China for over 40 years to prevent piglet paratyphoid. We compared the protective efficacies of subcutaneous (s.c.) and oral vaccination of BALB/c mice with C500 expressing the recombinant filamentous hemagglutinin type I domain and pertactin region 2 domain antigen (rF1P2) of Bordetella bronchiseptica. Protective efficacy against both S. enterica serovar Choleraesuis infection in an oral fatal challenge model and B. bronchiseptica infection in a model of fatal acute pneumonia was evaluated. Both the s.c. and oral vaccines conferred complete protection against fatal infection with the virulent parent S. enterica serovar Choleraesuis strain (C78-1). All 20 mice vaccinated s.c. survived intranasal challenge with four times the 50% lethal dose of virulent B. bronchiseptica (HH0809) compared with 4 of 20 vector-treated controls and 1 of 18 phosphate-buffered saline-treated controls that survived, but no significant protection against HH0809 was observed in orally vaccinated animals. Both the s.c. and oral vaccines elicited rF1P2-specific serum immunoglobulin G (IgG) and IgA antibodies. However, lung homogenates from s.c. vaccinated animals had detectably high levels of rF1P2-specific IgG and IgA; a much lower level of rF1P2-specific IgG was detected in samples from orally vaccinated mice, and the latter showed no evidence of local IgA. Furthermore, a more abundant and longer persistence of vaccine organisms was observed in the lungs of mice immunized s.c. than in those of mice immunized orally. Our results suggest that s.c. rather than oral vaccination is more efficacious in protecting mice from fatal challenge with B. bronchiseptica.     

Protective immunity against Plasmodium berghei malaria after administration of interleukin-12

Interleukin-12 (IL-12) has been shown to induce protection in mice against Plasmodium cyanomolgi and in rhesus monkey against Plasmodium yeolii. This study is to investigate whether recombinant IL-12 can induce protection in BALB/c mice against Plasmodium berghei. Five mice were given intraperitoneal injection of 7.5 micrograms/kg body weight recombinant mouse IL-12 two days prior to challenge with 5 x 10(4) of P. berghei, while mice in the control group were injected with 0.5 ml of normal saline prior to challenge. In both groups, the parasitaemia appeared on the fourth day after the infection. There was a slight reduction in the parasite burden in mice given IL-12 and the mice also survived longer compared to controls. Statistical significance of the difference could not be determined due to the small sample size. Nevertheless, the results of the study suggested that IL-12 may be able to protect mice against P. berghei infection.     

Cell-mediated immunity in mice vaccinated against malaria.

Mice vaccinated with a formalin-fixed preparation of either Plasmodium berghei or P. yoelli exhibited delayed type hypersensitivity (DTH) to the homologous antigen. This manifested itself in increased delayed thickening of antigen-challenged pinnae of the vaccinated mice as compared to the non-vaccinated controls. DTH was also evident in the vaccinated mice using the homing of radio-labelled bone marrow cells (BMC) to the delayed lesion as a criterion of reactivity. When P. yoelii vaccinated mice were given a live infection P. yoelii, a marked migration of BMC into the spleen occurred, with a peak at 48 hr, and it is suggested that this was a systemic response of DTH. The splenic T-cells of P. yoelii-vaccinated animals transformed in vitro with a soluble extract of the homologous parasite. The potential function of cell-mediated mechanisms in immunity to malarial infections is discussed.     

The effect of T and B lymphocyte depletion on the protection of mice vaccinated with a Gal E mutant of Salmonella typhimurium.

Immunosuppressive agents were used to determine the relative importance of T and B lymphocytes in conferring protection to mice vaccinated with a live gal E mutant of Salmonella typhimurium, strain G30D. Lymphocyte transformation and serum agglutination tests showed that while cyclophosphamide (CPA) suppressed B lymphocytes, antilymphocyte sea (ALS) suppressed both T and B cells. The humoral response of vaccinated animals treated with ALS was therefore supplemented by the i.v. injection of serum from untreated vaccinated mice. CPA-treated mice could not control multiplication of the vaccinal strain which eventually killed them. There was little multiplication of the vaccinal strain in the controls and ALS-treated mice, all of which survived to challenge. The vaccinated controls and vaccinated ALS treated groups each survived infection with the challenge strain which was gradually eliminated. It was concluded that humoral immunity was of greater importance than cellular immunity in mice vaccinated i.p. with strain G30D.     

Deficient Humoral Responses Underlie Susceptibility to Toxoplasma gondii in CD4-Deficient Mice

Resistance to infection with Toxoplasma gondii was studied in mice lacking CD4 expression. Such mice developed more brain cysts and survived for a shorter time than did wild-type controls after peroral infection with ME49 cysts. After immunization with the ts-4 strain of T. gondii, CD4-deficient mice exhibited impaired resistance to a challenge infection with virulent RH tachyzoites. Thus, deficient CD4 expression increases the susceptibility of mice to a primary peroral T. gondii infection with cysts and impairs their ability to be successfully vaccinated. CD8(+) T cells from blood or spleens of Toxoplasma-infected, CD4-deficient mice expressed markers of activation at frequencies similar to those of infected wild-type mice. Production of IFN-gamma in vitro was moderately depressed, and levels of Toxoplasma-specific immunoglobulin G2a in serum were substantially lower than in wild-type mice. Administration of Toxoplasma-immune serum to ts-4-vaccinated CD4-deficient mice significantly improved their resistance to RH challenge. Also, the survival of CD4-deficient mice chronically infected with ME49 was significantly prolonged by administration of immune serum. These results demonstrate that in addition to CD8(+) T cells and IFN-gamma, which are known to be critical for resistance, CD4(+) cells also contribute significantly to protection against chronic T. gondii infections and against challenge infections with highly virulent tachyzoites in immunized mice via their role as helper cells for production of isotype-switched antibodies.     

Two distinct types of non-specific immunosuppression in murine malaria.

A comparative study of non-specific immunosuppression by malaria has been carried out in five situations: in both unvaccinated and vaccinated mice infected with the lethal Plasmodium yoelii or the lethal Plasmodium berghei, and in the unvaccinated non-lethal P. yoelii infection. Spleen cells showed a suppressive effect on the normal blastogenic response to mitogens. This suppression was strongest in the mice vaccinated before infection with the lethal P. yoelii and in those infected with non-lethal P. yoelii, suggesting that the suppressive effect did not interfere with recovery. Silica, anti-Thy-1, and indomethacin treatment suggested that this suppression was caused by macrophages. However, the plaque-forming cell response to sheep RBC in vivo was suppressed equally in every case at the peak of the parasitaemia, whereas the suppression of contact sensitivity to oxazolone was strongest in mice with fatal infections. We suggest that different suppressor mechanisms operate in malaria, some being harmful to the host and others possibly beneficial.     

Effect of selenium and dimethyl dioctadecyl ammonium bromide on the vaccine-induced immunity of Swiss-Webster mice against malaria (Plasmodium berghei).

The results of the study described in this paper demonstrate that selenium, administered in drinking water, potentiates the protective effect of a killed Plasmodium berghei vaccine for Swiss-Webster mice. We also report that a vaccine consisting of P. berghei antigen combined with the adjuvant dimethyl dioctadecyl ammonium bromide conferred a significantly high level of protective immunity. An additive effect was shown in that the greatest degree of protection was afforded to the group of mice maintained on selenium and vaccinated with antigen-dimethyl dioctadecyl ammonium bromide. Almost all of the animals treated in this manner survived the challenging infection, the course of which was typically of a transitory parasitemia not exceeding 10% at the peak.     

Infection with Plasmodium berghei boosts antibody responses primed by a DNA vaccine encoding gametocyte antigen Pbs48/45

An important consideration in the development of a malaria vaccine for individuals living in areas of endemicity is whether vaccine-elicited immune responses can be boosted by natural infection. To investigate this question, we used Plasmodium berghei ANKA blood-stage parasites for the infection of mice that were previously immunized with a DNA vaccine encoding the P. berghei sexual-stage antigen Pbs48/45. Intramuscular immunization in mice with one or two doses of DNA-Pbs48/45 or of empty DNA vaccine as control did not elicit detectable anti-Pbs48/45 antibodies as determined by enzyme-linked immunosorbent assay. An infection with P. berghei ANKA 6 weeks after DNA vaccination elicited comparable anti-Pbs48/45 antibody levels in mice which had been primed with DNA-Pbs48/45 or with empty DNA vaccine. However, a repeat infection with P. berghei ANKA resulted in significantly higher anti-Pbs48/45 antibody levels in mice which had been primed with the DNA-Pbs48/45 vaccine than the levels in the mock DNA-vaccinated mice. In parallel and as an additional control to distinguish the boosting of Pbs48/45 antibodies exclusively by gametocytes during infection, a separate group of mice primed with DNA-Pbs48/45 received an infection with P. berghei ANKA clone 2.33, which was previously described as a "nongametocyte producer." To our surprise, this parasite clone too elicited antibody levels comparable to those induced by the P. berghei gametocyte producer clone. We further demonstrate that the nongametocyte producer P. berghei clone is in fact a defective gametocyte producer that expresses Pbs48/45, much like the gametocyte producer clone, and is therefore capable of boosting antibody levels to Pbs48/45. Taken together, these results indicate that vaccine-primed antibodies can be boosted during repeat infections and warrant further investigation with additional malaria antigens.     

Nematode-induced interference with the anti-Plasmodium CD8+ T-cell response can be overcome by optimizing antigen administration

Malaria is still responsible for up to 1 million deaths per year worldwide, highlighting the need for protective malaria vaccines. Helminth infections that are prevalent in malaria endemic areas can modulate immune responses of the host. Here we show that Strongy-Ioides ratti, a gut-dwelling nematode that causes transient infections, did not change the efficacy of vaccination against Plasmodium berghei. An ongoing infection with Litomosoides sigmodontis, a tissue-dwelling filaria that induces chronic infections in BALB/c mice, significantly interfered with vaccination efficacy. The induction of P. berghei circumspor-ozoite protein (CSP)-specific CD8(+) T cells, achieved by a single immunization with a CSP fusion protein, was diminished in L. sigmodontis-infected mice. This modulation was reflected by reduced frequencies of CSP-specific CD8(+) T cells, reduced CSP-specific IFN-y and TNF-a production, reduced CSP-specific cytotoxicity, and reduced protection against P. berghei challenge infection. Implementation of a more potent vaccine regime, by first priming with CSP-expressing recombinant live Salmonella prior to CSP fusion protein immunization, restored induction of CSP-specific CD8(+) T cells and conferred almost sterile immunity to P. berghei challenge infection also in L. sigmodontis-infected mice. In summary, we show that appropriate vaccination regimes can overcome helminth-induced interference with vaccination efficacy.     

Anti-lymphocyte antibodies in lethal mouse malaria. II. Induction of an autoantibody specific suppressor T cell by non-lethal P. yoelii

The anti-lymphocyte autoantibody response to irradiated lethal Plasmodium berghei malaria parasites in normal mice was significantly reduced when recipients were pre-treated with splenic T cells from mice recovered from a non-lethal Plasmodium yoelii infection. Suppression was specific for the autoantibody and did not affect the antibody response to the parasite. Experiments involving sequential P. yoelii-P. berghei infections in situ revealed that recovery from P. berghei was possible when the interval between the two infections was 14 days or more. This ability to recover from P. berghei correlated with a progressive reduction of anti-lymphocyte autoantibody suggesting a useful role for the suppressor cell. The possible link between suppressor cells and anti-lymphocyte autoantibodies in malaria is discussed.     

The role of the liver in immunity to blood-stage murine malaria.

Mice vaccinated with fixed parasitized red blood cells and Bordetella pertussis can clear an otherwise lethal Plasmodium yoelii infection in 7 days; this protection is abolished by splenectomy before vaccination. Most mice splenectomized following vaccination were able to clear their infections, although their recovery was delayed. When labelled parasitized red cells were injected into mice during an infection, splenic uptake fell from day 3 onwards while uptake by the liver increased. Lymphocytes (mainly T cells) formed the majority of the live cells extracted from livers 7 days after infection, although blasts and myeloid cells were also present. Infected livers from vaccinated mice contained most cells. Less marked increases were observed 7 days after P. berghei infection of vaccinated mice. Examination of liver tissue showed that the sinusoids contained increased numbers of cells and suggested that activation of Kupffer cells was occurring, particularly in vaccinated mice infected with P. yoelii. Homing experiments confirmed the increased trapping of various cells in livers of vaccinated mice infected with P. yoelii. These results suggest an important role for the liver in recovery from blood-stage malaria infection.     

Increased influenza pneumonia mortality of mice adoptively immunized with node and spleen cells sensitized by inactivated but not live virus.

Syngeneic mice adoptively immunized intravenously with 25 million washed node and spleen cells from donors vaccinated subcutaneously with formolized influenza A PR8 had a higher mortality with influenza pneumonia after challenge with homologous virus than occurred in recipients of similar cells from unsensitized donors, and this increased mortality was prevented by treatment of the sensitized cells with antithymocyte serum. Mice adoptively immunized with cells from donors vaccinated with formolized influenza A PR8 also had a higher mortality than recipients of unsensitized cells after challenge with heterologous influenza B Lee. Mice who received PR8-sensitized cells and survived challenge with influenza B Lee developed antibody only to the challenge virus, and serum antibody titers to the challenge virus in surviving recipients of sensitized cells were similar to those of recipients of unsensitized cells in all studies. Influenza mortality of recipients of antibody-containing mouse serum after homologous virus challenge was similar to that of recipients of antibody-free mouse serum in this model. Washed node and spleen cells from donor mice who had survived respiratory infection or received subcutaneous vaccination with live influenza A PR8 and those from donor mice given typhoid vaccine subcutaneously all failed to alter mortality from that observed in recipients of unsensitized cells after challenge with influenza A PR8. These results suggest that subcutaneous vaccination with inactivated influenza establishes a reactivity of the cell-mediated immunologic system which can increase the severity of influenza infection of the respiratory tract under certain conditions, and that sensitization by live influenza fails to produce this effect.     

Oral vaccination of BALB/c mice with Salmonella enterica serovar Typhimurium expressing Pseudomonas aeruginosa O antigen promotes increased survival in an acute fatal pneumonia model

Pseudomonas aeruginosa is a leading cause of nosocomial pneumonia. We compared the efficacies of oral and intraperitoneal (i.p.) vaccinations of BALB/c mice with attenuated Salmonella enterica serovar Typhimurium SL3261 expressing P. aeruginosa serogroup O11 O antigen to protect against P. aeruginosa infection in an acute fatal pneumonia model. Oral and i.p. vaccines elicited O11-specific serum immunoglobulin G (IgG) antibodies, but IgA was observed only after oral immunization. Challenge of orally vaccinated mice with an O11 strain (9882-80) at 6 and 12 times the 50% lethal dose showed increased survival in mice that received the vaccine compared to phosphate-buffered saline (PBS)- and vector-treated controls; no difference in survival was seen with a heterologous strain, 6294 (serogroup O6). In addition, significant protection against 9882-80 was not observed in i.p. vaccinated animals. Bronchoalveolar lavage fluid taken from immunized mice harbored O11-specific IgA and IgG in orally immunized mice but only modest levels of IgG in i.p. vaccinated mice. To correlate protection, opsonophagocytosis assays were performed with pooled sera from orally immunized animals. Efficient killing of five O11 clinical isolates was observed, while no killing was noted with 6294, indicating that the recombinant SL3261 oral vaccine induces an O11-specific reaction. We next determined the ability of orally vaccinated animals to clear bacteria from their lungs. Following P. aeruginosa challenge, the numbers of viable bacteria were significantly fewer in orally vaccinated animals than in PBS- and vector-treated controls. Our results suggest that oral immunization with recombinant SL3261 is efficacious in protection against pneumonia caused by P. aeruginosa.     

Macrophage cytotoxicity in lethal and non-lethal murine malaria and the effect of vaccination.

We investigated the development of cell-mediated immunity in lethal and non-lethal malarial infections by assaying the cytotoxic activity of spleen cells for L929 tumour cells at different times after infection of mice with the lethal P. berghei, a lethal variant of Plasmodium yoelii and the non-lethal P. yoelii and P. chabaudi. In all cases the cytotoxicity increased to a peak during the first week and then diminished but the time of the peak varied with the infection; its activity was lowest with P. berghei. A second peak occurred in the non-lethal infections at the time of recovery. A protective vaccine accelerated and enhanced the early peak of cytotoxicity. The activity was mediated by adherent phagocytic cells, probably through the release of tumour necrosis factor (TNF) by macrophages since it was inhibited by antiserum against recombinant mouse TNF and did not destroy TNF-resistant L929 cells. Its induction was not dependent on T cells since it occurred in T cell-deficient mice infected with non-lethal P. yoelii. However, the accelerated increase associated with vaccination could be adoptively transferred by spleen lymphocytes from vaccinated mice.     

Alpha C protein as a carrier for type III capsular polysaccharide and as a protective protein in group B streptococcal vaccines

The alpha C protein, a protective surface protein of group B streptococci (GBS), is present in most non-type III GBS strains. Conjugate vaccines composed of the alpha C protein and type III capsular polysaccharide (CPS) might be protective against most GBS infections. In this study, the type III CPS was covalently coupled to full-length, nine-repeat alpha C protein (resulting in III-alpha9r conjugate vaccine) or to two-repeat alpha C protein (resulting in III-alpha2r conjugate vaccine) by reductive amination. Initial experiments with the III-alpha9r vaccine showed that it was poorly immunogenic in mice with respect to both vaccine antigens and was suboptimally efficacious in providing protection in mice against challenge with GBS. Therefore, modified vaccination protocols were used with the III-alpha2r vaccine. Female mice were immunized three times with 0.5, 5, or 20 microgram of the III-alpha2r vaccine with an aluminum hydroxide adjuvant and bred. Ninety-five percent of neonatal mice born to dams immunized with the III-alpha2r vaccine survived challenge with GBS expressing type III CPS, and 60% survived challenge with GBS expressing wild-type (nine-repeat) alpha C protein; 18 and 17%, respectively, of mice in the negative control groups survived (P, <0.0001). These protection levels did not differ significantly from those obtained with the type III CPS-tetanus toxoid conjugate vaccine and the unconjugated two-repeat alpha C protein, which protected 98 and 58% of neonates from infection with GBS expressing type III CPS or the alpha C protein, respectively. Thus, the two-repeat alpha C protein in the vaccine was immunogenic and simultaneously enhanced the immunogenicity of type III CPS. III-alpha vaccines may be alternatives to GBS polysaccharide-tetanus toxoid vaccines, eliciting additional antibodies protective against GBS infection.     

Immunogenicity and protection against genital Chlamydia infection and its complications by a multisubunit candidate vaccine.

BACKGROUND AND PURPOSE: Genital infections due to Chlamydia trachomatis pose a considerable public health challenge worldwide and a vaccine is urgently needed to protect against these infections. We examined whether a vaccine composed of a combination of the major outer membrane protein (MOMP) and porin B protein (PorB) of C. trachomatis would have a protective advantage over a single subunit construct. METHODS: Single and multisubunit vaccines expressing MOMP and PorB were constructed and evaluated in the mouse model of genital infection. Thus, groups of female C57BL/6 mice were immunized intramuscularly with recombinant Vibrio cholerae ghosts (VCG) expressing the vaccine antigens or VCG alone and humoral and cell-mediated immune responses were evaluated. RESULTS: Significant levels of Chlamydia-specific secretory immunoglobulin A and immunoglobulin G2a were detected in vaginal washes and serum of immunized mice. The multisubunit construct induced a significantly higher level of T-helper Type 1 response than the single subunits as measured by the amount of interferon-gamma produced by immune T cells in response to re-stimulation with ultraviolet-irradiated elementary bodies in vitro. Three weeks after the last immunization, animals were challenged intravaginally with 10(7) inclusion-forming units of C. trachomatis serovar D. There was a significant difference in the intensity and duration of vaginal shedding between the vaccine-immunized mice and controls. All the animals immunized with the multisubunit vaccine had completely resolved the infection 2 weeks post-challenge. Higher numbers of embryos were observed in vaccinated animals than in controls, indicating protection against infertility. CONCLUSION: These results underscore the potential, albeit moderate, vaccine advantage of the multisubunit formulation.     

结核分枝杆菌Ag85B基因疫苗免疫保护作用的初步研究

目的:研究编码结核分枝杆菌分泌蛋白Ag85B的基因疫苗pTB30m和pTB30s对免疫动物的保护作用。方法:以基因疫苗pTB30m和pTB30s肌注免疫BALB/c小鼠。免疫完成6 wk后,用5×105 CFU的MTB H37Rv毒株经小鼠尾静脉攻击感染。同时用尼龙毛柱分离基因免疫BALB/c小鼠的T细胞,并以5×106 T细胞/只小鼠过继免疫正常BALB/c小鼠,立即用105 CFU的MTB毒株经小鼠尾静脉攻击感染。4 wk后分别计数脾脏中的细菌负荷。结果:与生理盐水对照组相比较,pTB30m及pTB30s质粒免疫组BALB/c小鼠脾脏中的细菌负荷均减少,分别为0.645(log10 CFU,P<0.01)和0.839(log10CFU,P<0.001);而空质粒对照组小鼠脾脏中的细菌负荷减少较少。经质粒pTB30m和pTB30s免疫的BALB/c小鼠的T细胞,过继免疫的正常BALB/c小鼠,对攻击感染的MTB H37Rv毒株在脾脏中的增殖具有部分抑制作用。结论:pTB30s免疫的BALB/c小鼠,对MTB H37 Rv毒株攻击的保护作用优于pTB30m质粒免疫,有望进一步用于结核病的防治研究。