Induction of protective immunity against Schistosoma mansoni by a nonliving vaccine. II. Response of mouse strains with selective immune defects

The efficacy of a new vaccination procedure against Schistosoma mansoni, involving intradermal injection of nonliving antigen combined with the bacterial adjuvant Mycobacterium bovis strain bacillus Calmette Guérin, was tested in several strains of mice. Development of protection against subsequent infection was compared with in vivo skin test reactivity and in vitro humoral reactivity to soluble and surface-associated schistosome antigens. Significant levels of resistance and immune response were displayed by many inbred mouse strains, including C57BL/6J, C3H/HeN, and CBA/J, as well as outbred Swiss-Webster mice. However, no definite correlation was observed between the level of any particular immune response and the level of resistance to challenge S. mansoni infection. Development of protective immunity was also examined in mice with various immune defects, to determine whether these responses are relevant to resistance in this model. Animals with defective specific immediate hypersensitivity response due to deficiencies in IgE (SJL/J) or mast cell (W/Wv) production displayed strong resistance as a result of immunization. Likewise, mice bearing the lpsd (C3H/HeJ) or xid (CBA/N) mutations, affecting cellular or humoral response to certain thymus-independent antigens, developed significant levels of resistance after immunization. A/J mice, with defects in cellular recognition of bacterial endotoxin as well as deficiencies in natural killer cell activity and complement function, also showed significant protective immunity. Thus, these reactivities do not appear to be essential to the resistance against S. mansoni induced by the nonliving vaccine. Two nonresponder strains were identified, P and BALB/c. P mice were defective in specific delayed hypersensitivity response as well as resistance to infection. However, BALB/c mice showed no obvious immune deficiencies at the time of challenge. These results agreed with previous findings in mice immunized by exposure to radiation-attenuated cercariae with one exception; BALB/c mice were protected by vaccination with irradiated cercariae but not by the nonliving vaccine. Thus, further examination of immune response in mice identified in this study as high and low responder strains should allow characterization of critical immune resistance mechanisms induced by the nonliving vaccine, as well as immune mechanisms operating in common between these two models of resistance to S. mansoni.     

Mucosal Application of gp140 Encoding DNA Polyplexes to Different Tissues Results in Altered Immunological Outcomes in Mice

Increasing evidence suggests that mucosally targeted vaccines will enhance local humoral and cellular responses whilst still eliciting systemic immunity. We therefore investigated the capacity of nasal, sublingual or vaginal delivery of DNA-PEI polyplexes to prime immune responses prior to mucosal protein boost vaccination. Using a plasmid expressing the model antigen HIV CN54gp140 we show that each of these mucosal surfaces were permissive for DNA priming and production of antigen-specific antibody responses. The elicitation of systemic immune responses using nasally delivered polyplexed DNA followed by recombinant protein boost vaccination was equivalent to a systemic prime-boost regimen, but the mucosally applied modality had the advantage in that significant levels of antigen-specific IgA were detected in vaginal mucosal secretions. Moreover, mucosal vaccination elicited both local and systemic antigen-specific IgG⁺ and IgA⁺ antibody secreting cells. Finally, using an Influenza challenge model we found that a nasal or sublingual, but not vaginal, DNA prime/protein boost regimen protected against infectious challenge. These data demonstrate that mucosally applied plasmid DNA complexed to PEI followed by a mucosal protein boost generates sufficient antigen-specific humoral antibody production to protect from mucosal viral challenge.     

Ascaris suum: homocytotropic antibody responses in mice.

Homocytotropic antibodies in the sera of CD-1 and DBA/1 mice infected with larval A. suum were titered by PCA reactions. IgG₁ and reaginic antibody responses were similar in both strains of mice. With a dose of 8000 to 10,000 embryonated eggs, reaginic antibody was detected during the second week and IgG₁ antibody during the third week of infection. Doses of 1500 to 5000 eggs gave delayed antibody responses or did not induce a detectable response, although an anamnestic response followed a challenge inoculation even when no detectable antibody was observed in initial infection. Larval A. suum infections in two strains of mice did not potentiate a reaginic response to ovalbumin.     

Heligmosomoides polygrus (equals nematospiroides dubius): humoral and intestinal immunologic responses to infection in mice

Measurements of serum IgG₁, IgG_2a, IgM, and IgA levels and antibody titers in these immunoglobulin classes were made at intervals after initial infection and challenge infection of mice immunized by two or three previous infections. Identical measurements were made on the content of the small intestine in mice which had been exposed to the same infection schedule. Sections of small intestine taken after initial infection and challenge infection were examined by the fluorescent antibody technique for changes in populations of immunoglobulin-containing cells and by routine histologic procedures for histopathologic changes.In serum, only IgG₁ was consistently increased after initial infection, and antibody in IgG₁ was detected within the first 2 wk of infection. In immunized animals, only IgG₁ and antibody of this class always responded to challenge infection, although antibody in other immunoglobulin classes was detected.IgA concentration of the intestinal content did not differ significantly after initial infection or challenge infection of immunized mice. Immunized mice had about twice the IgG₁ concentration in intestinal content as singly infected animals. No intestinal antibody was detected after initial infection; only IgG₁ antibody was detected in the intestinal content of immunized and challenged mice.Cell infiltrates in the intestinal mucosa and submucosa of immunized animals contained numerous IgG₁-containing cells. Mast cells and globular leukocytes were observed in the intestine of immunized animals.     

Defective vaccine-induced immunity to Schistosoma mansoni in P strain mice. I. Analysis of antibody responses

Inbred P4 strain mice have previously been shown to be uniquely defective in their resistance to challenge infection induced by irradiated cercariae of Schistosoma mansoni. To assess whether the low levels of resistance developed by vaccinated P mice could be due to a defective antibody response, we compared the anti-schistosomulum antibody responses in vaccinated P animals with those occurring in vaccinated C57BL/6J (B6) mice, a strain that consistently develops high levels of resistance to challenge infection. Our results indicate that vaccinated P mice develop levels of total anti-schistosomulum antibodies that are significantly lower than those occurring in B6 mice for at least 15 wk after immunization, with the exception of the fifth week, at which time the responses are indistinguishable. Further analysis revealed that the defect in P strain antibody response occurs specifically in the IgM isotype and that specific IgM levels in P mice are less than one-half the levels in B6 mice at every time point examined. In contrast, no differences in total IgM immunoglobulins were evident when sera from normal (nonvaccinated) P and B6 mice were compared. P mouse anti-schistosomulum IgG antibody responses reached the same levels as those observed in B6 mice by 5 wk after vaccination. However, a much faster decay in IgG antibody levels occurred after this time point in P animals. No differences were observed when the levels of anti-schistosomulum antibodies occurring in each of the major IgG isotypes (IgG1, IgG2a, IgG2b, IgG3) were compared in sera from P and B6 mice vaccinated 4 wk previously. Similarly, vaccinated P and B6 mice were found to mount indistinguishable IgG anamnestic responses after challenge infection. Finally, no differences between vaccinated P and B6 mice were observed when immediate (30 min) skin test and mast cell degranulation responses to a soluble schistosome antigenic preparation were compared. The above findings suggest that P strain mice have a specific defect in their ability to mount IgM antibody responses after immunization with irradiated cercariae. The possible contribution of this defect in IgM response to the decreased resistance of vaccinated P mice to challenge infection is discussed.     

The effect of aging on the induction of humoral and cellular immunity and tolerance in two long-lived mouse strains.

Aging is a complex process that adversely affects most if not all components of the immune system. In this report, two long-lived mouse strains have been compared in ability to generate both antigen-specific immunity and tolerance. Although CBA/CaJ mice produced high levels of antibody following injection of aqueous preparations of aggregated human gamma-globulin (AHGG), C57BL/6 mice made only meager antibody responses to such preparations. Age dramatically affects the humoral anti-HGG response to aqueous AHGG in both strains, but the meager response of young C57BL/6 mice was at insignificant levels in aged C57BL/6 mice. Conversely, both mouse strains generated good responses following injection of HGG in complete Freund's adjuvant at both the T and B cell level as evidenced by in vitro antigen-specific T cell proliferation and anti-HGG antibody production. Aged mice of both strains showed a marked decrease in the production of serum anti-HGG antibody in comparison to young mice. Although the antigen-specific T cell proliferative response was significantly decreased in aged CBA/CaJ mice, such proliferation was not affected in aged mice of the C57BL/6 strain. Removal of CD8+ cells from lymph node T cells of either young or aged C57BL/6 mice did not increase the antigen-specific proliferative response, suggesting that loss of CD8+ suppressors during the aging process is not responsible for the high level of antigen-specific T cell proliferation in aged C57BL/6 mice. Tolerance to HGG was readily induced in both young and aged C57BL/6 and CBA/CaJ mice although aged mice demonstrate a modest resistance to tolerance induction when compared to their young counterparts. This resistance was observed in both antibody production and antigen-specific T cell proliferation.     

Identification of a genetic locus, Rsm-1, controlling protective immunity against Schistosoma mansoni

Mice of most inbred strains develop moderate to high levels of resistance to challenge infection on vaccination with radiation-attenuated cercariae of Schistosoma mansoni. P strain mice, however, fail to display significant protective immunity after exposure to the same vaccine. To examine the genetic basis of this polymorphism in host immunity, vaccine-induced resistance was examined in (C57/BL6J X P/N)F1, F2, and reciprocal backcross generations. The defective immunity which characterizes the P strain parent was found to be inherited in a fully recessive manner and to be controlled by a single genetic locus, which we have designated Rsm-1. Linkage analyses revealed that Rsm-1 is not genetically associated with the major histocompatibility complex (chromosome 17), the immunoglobulin heavy chain locus (chromosome 12), or a single locus influencing defective anti-schistosomulum IgM antibody responses in the P parental stock. These data provide the first example of single gene control of vaccine-induced immunity against a helminth infection. Because P mice are also defective in their capacity to develop tumoricidal macrophages and in their immunity to Leishmania major, genes encoded by the Rsm-1 locus may play a general role in resistance to infection and malignancy.     

Trichinella spiralis: anaphylactic antibody formation and susceptibility in strains of inbred mice.

The anaphylactic antibody response of various strains of inbred mice of different H-2 specificities was investigated using the passive cutaneous anaphylactic technique (PCA) for the detection of the antibody response. Neither IgC₁ nor reaginic antibody were detected in serum samples obtained at the end of the first week of infection with Trichinella spiralis. Subsequently, all animals had detectable IgG₁ antibodies, although in some strains the titers were very low. Reaginic antibody was detected in relatively high titers in C57L, A, and DBA/1 mice. Two other strains were very poor responders (SJL and AKR). In most strains, reagin and IgG₁ remained detectable for 14 wk or longer. The pattern of response of all strains was very reproducible, indicating genetic control of the anaphylactic antibody production to the infection. In F₁ hybrids obtained from crosses between good and poor anaphylactic antibody responders, intermediate levels of both antibody classes were detected.Adult worm recovery rates were established at various points during the intestinal phase of infection, and no correlation between worm numbers and reaginic antibody titers in the various strains of mice could be demonstrated. There were noticeable differences in larval yields obtained after muscle digestion of mice belonging to the different inbred strains. In fact, we generally observed an inverse relationship between the number of larvae recovered from a given strain and their reaginic antibody titer.The intravenous injection of newborn larvae (NBL), obtained upon in vitro incubation of adult worms, produced detectable antibodies only in mice of the DBA/1 strain. These antibodies were consistently of low titer and became detectable only after the administration of two additional injections of NBL. This contrasted with the results observed after “per os” infection of DBA/1 mice, where high titers of these antibodies were always obtained, in spite of comparable ratios of muscle larval yield.     

Plasmodium berghei: antibody response and protective immunity induced by vaccination

The authors have studied the behaviour of Swiss mice and of 5 inbred strains of mice in order to investigate: the protective effect, in the homologous infection test, of six vaccine inoculations of irradiated parasites belonging to two strains of Plasmodium berghei: ISTISAN and K173; the capacity to produce humoral antibodies after vaccine treatments and during infection; the probable correlation between the high antibody titre and the protection against infection. The results of the present study show that the antibody response plays a precise role in the immunity induced by vaccination. There is a certain degree of correlation, which is more evident for K173 vaccine, between the level of antibody response during infection and the protective efficacy of vaccination.     

Subcutaneous administration CpG-ODNs acts as a potent adjuvant for an HIV-1-<Emphasis Type="Italic">tat</Emphasis>-based vaccine candidate to elicit cellular immunity in BALB/c mice

Objective

To evaluate the combined effects of CpG oligodeoxynucleotides (CpG-ODNs) adjuvant and subcutaneous injection route on efficacy of a HIV-1-tat DNA vaccine candidate using BALB/c mice as an animal model.

Results

Evaluation of cellular and humoral immunity of mice injected subcutaneously with HIV-1-tat gene cloned into a pcDNA3.1 vector indicated that significant levels of IFN-γ cytokine secretion (900 pg/ml), lymphocyte proliferation (2.5 stimulation index) and IgG_2a (1.45 absorbance 450 nm) production could be achieved. These indicators of stimulated cellular immunity were elicited 2 weeks after the last injection (P < 0.05).

Conclusions

Formulation of HIV-1-tat DNA vaccine candidate with CpG-ODNs as an adjuvant while administrated subcutaneously are a promising approach to induce effective cellular immunity responses against HIV-1 infection.

     

Immunological dynamics in response to two anthrax vaccines in mice

In order to understand the variation of humoral and cellular immune responses to A16R live spore and AVA vaccine and to identify efficient immunological parameters for the early evaluation of post immunization in mice, we dynamically monitored the antibody production and cellular responses after the vaccination of Balb/C mice with the anthrax vaccines. The results show that both anti-AVA and anti-Spore antibodies were detectable in the A16R live spore vaccinated group while high titers of anti-AVA antibodies but not anti-Spore antibodies existed in the AVA-immunized group. IgG1 and IgG2 were the major subtypes of IgG in both of the two groups. However, the IgG2a level was significantly higher in the A16R group than in the AVA group. At the cellular level, responses of antigen-specific TH2, TH1 and plasma cells were detected. The peripheral T_H2 responses could be seen on day 5 after vaccination, and remained at a high level throughout the experiment (from day 5 post primary immunization to day 60 post the tertiary immunization); the T_H1 responses to A16R vaccine appeared on day 5, while the responses to AVA could only be detected by day 7 after the secondary immunization; a low level of T_H1 responses could be observed at the end of the experiment. Antigen-specific plasma cells could be found in the peripheral blood of both the immunized groups, however, the responses in the A16R group appeared earlier, lasted longer, and shown an ascending tendency until the end of the experiment when the plasma cell responses in the AVA group were reduced to a very low level. The results suggest that the multiple antigen containing A16R live spore vaccine induces better immune responses than AVA. Combined with serum antibody titers, T_H2, T_H1 and plasma cell responses could be used as immunological parameters for the evaluation of vaccine efficacy. These findings may afford new insight into the early evaluation of vaccination as well as being a powerful strategy for vaccine development.     

Duration of antiviral immunity after smallpox vaccination

Although naturally occurring smallpox was eliminated through the efforts of the World Health Organization Global Eradication Program, it remains possible that smallpox could be intentionally released. Here we examine the magnitude and duration of antiviral immunity induced by one or more smallpox vaccinations. We found that more than 90% of volunteers vaccinated 25-75 years ago still maintain substantial humoral or cellular immunity (or both) against vaccinia, the virus used to vaccinate against smallpox. Antiviral antibody responses remained stable between 1-75 years after vaccination, whereas antiviral T-cell responses declined slowly, with a half-life of 8-15 years. If these levels of immunity are considered to be at least partially protective, then the morbidity and mortality associated with an intentional smallpox outbreak would be substantially reduced because of pre-existing immunity in a large number of previously vaccinated individuals.     

Specific Humoral Immunity versus Polyclonal B Cell Activation in Trypanosoma cruzi Infection of Susceptible and Resistant Mice

Background

The etiologic agent of Chagas Disease is Trypanosoma cruzi. Acute infection results in patent parasitemia and polyclonal lymphocyte activation. Polyclonal B cell activation associated with hypergammaglobulinemia and delayed specific humoral immunity has been reported during T. cruzi infection in experimental mouse models. Based on preliminary data from our laboratory we hypothesized that variances in susceptibility to T. cruzi infections in murine strains is related to differences in the ability to mount parasite-specific humoral responses rather than polyclonal B cell activation during acute infection.

Methodology/Principal Findings

Relatively susceptible Balb/c and resistant C57Bl/6 mice were inoculated with doses of parasite that led to similar timing and magnitude of initial parasitemia. Longitudinal analysis of parasite-specific and total circulating antibody levels during acute infection demonstrated that C57Bl/6 mice developed parasite-specific antibody responses by 2 weeks post-infection with little evidence of polyclonal B cell activation. The humoral response in C57Bl/6 mice was associated with differential activation of B cells and expansion of splenic CD21^highCD23^low Marginal Zone (MZ) like B cells that coincided with parasite-specific antibody secreting cell (ASC) development in the spleen. In contrast, susceptible Balb/c mice demonstrated early activation of B cells and early expansion of MZ B cells that preceded high levels of ASC without apparent parasite-specific ASC formation. Cytokine analysis demonstrated that the specific humoral response in the resistant C57Bl/6 mice was associated with early T-cell helper type 1 (Th1) cytokine response, whereas polyclonal B cell activation in the susceptible Balb/c mice was associated with sustained Th2 responses and delayed Th1 cytokine production. The effect of Th cell bias was further demonstrated by differential total and parasite-specific antibody isotype responses in susceptible versus resistant mice. T cell activation and expansion were associated with parasite-specific humoral responses in the resistant C57Bl/6 mice.

Conclusions/Significance

The results of this study indicate that resistant C57Bl/6 mice had improved parasite-specific humoral responses that were associated with decreased polyclonal B cell activation. In general, Th2 cytokine responses are associated with improved antibody response. But in the context of parasite infection, this study shows that Th2 cytokine responses were associated with amplified polyclonal B cell activation and diminished specific humoral immunity. These results demonstrate that polyclonal B cell activation during acute experimental Chagas disease is not a generalized response and suggest that the nature of humoral immunity during T. cruzi infection contributes to host susceptibility.     

The absence of VPAC2 leads to aberrant antibody production in Aspergillus fumigatus sensitized and challenged mice

Vasoactive intestinal peptide (VIP) facilitates a “pro-allergy” phenotype when signaling through its G protein-coupled receptor, VPAC₂. We have shown that VPAC₂ knock-out (KO) mice developed an allergic phenotype marked by eosinophilia and elevated serum IgE. Therefore, we hypothesized that the humoral response to allergen challenge in these mice was T_H2 dominant similar to wild-type (WT) C57BL/6 mice. Antibody responses in WT and KO mice were measured after Aspergillus fumigatus conidia inhalation. In contrast to previous reports, basal levels of serum IgG_2a and IgA were significantly higher in naïve VPAC₂ KO animals. Antibody availability in the serum as well as the bronchoalveolar lavage fluid after fungal challenge was dominated by the pro-inflammatory isotype IgG_2a and the mucosal isotype, IgA. IgA localizing cells dominated in the peribronchovascular areas of allergic KO mice while IgE immune complexes were found in WT allergic lungs. This research shows for the first time that VPAC₂ has a significant effect on antibody regulation, in the context of allergy.     

Improvement of adaptive immunity by antigen-carrying biodegradable nanoparticles

One of the most important aspects in vaccine development is to induce potent antigen-specific immune responses. In this study, we examined the immunological activities of antigen-carrying biodegradable poly(γ-glutamic acid) (γ-PGA) nanoparticles (NPs) in mice. The immunization with ovalbumin (OVA)-carrying γ-PGA NPs (OVA-NPs) could induce significant expansion of antigen-specific CD8⁺ T cells. Unlike complete Freund’s adjuvant, subcutaneous (s.c.) inoculation of OVA-NPs to footpad did not generate injection site swelling. Although OVA-NPs could induce both antigen-specific cellular and humoral immune responses, the dominant induction of either cellular or humoral immunity was found to depend on their administration routes. Strong antibody production was observed by s.c. immunization, yet no antibody was identified by intranasal immunization. Thus, γ-PGA NPs are a safe and efficient antigen carrier with unique immunological properties.     

Induction of Th1-type immunity and tumor protection with a prostate-specific antigen DNA vaccine

Prostate specific antigen (PSA) is a serum marker that is widely used in the detection and monitoring of prostate cancer. Though PSA is a self-antigen, T cell responses to PSA epitopes have been detected in healthy men and prostate cancer patients, suggesting it may be used as a target for active immunotherapy of prostate cancer. A PSA DNA vaccine (pPSA) was evaluated in mice and monkeys for its ability to induce antigen-specific immune responses. Mice immunized intradermally with pPSA demonstrated strong PSA-specific humoral and cellular immunity. The anti-PSA immune responses were skewed toward Th1, as shown by high IFN and IL-2 production. The immune response was sufficient to protect mice from challenge with PSA-expressing tumor cells. Tumor protection was durable in the absence of additional vaccination, as demonstrated by protection of vaccinated mice from tumor rechallenge. Furthermore, pPSA vaccination induced PSA-specific antibody titers in male cynomolgus monkeys, which express a closely related PSA gene. These results demonstrate that vaccination with pPSA may be able to break tolerance and can induce an immune response that mediates tumor protection.     

乙型肝炎病毒全S基因疫苗诱导小鼠的特异性免疫应答

乙型肝炎病毒 (ＨＢＶ)感染是我国常见病及多发病。ＨＢＶ难以清除的原因之一就是机体的免疫功能障碍。目前虽然基因重组ＨＢＶ表面抗原 (ＨＢｓＡｇ)疫苗预防ＨＢＶ感染取得了较好的效果 ,但基因重组ＨＢｓＡｇ疫苗主要能诱导特异性体液免疫 ,不能刺激机体的细胞免疫应答。近年来发现基因疫苗可诱导机体产生细胞及体液免疫反应 ,特别是诱导细胞免疫反应的能力优于蛋白、多肽类疫苗 ,更适应于慢性病毒感染的预防与治疗[1,2 ] 。为了探讨应用ＨＢＶ基因疫苗预防ＨＢＶ感染的可能性 ,本文构建了ＨＢＶ全Ｓ基因和ＨＢｓＡｇ基因疫苗 ,观察和比…     

Effects of testosterone on cell-mediated and humoral immunity in non-breeding adult European starlings

One of the primary assumptions of the immunocompetence hypothesisis that testosterone is immunosuppressive. Although many studiesin birds and mammals have supported this assumption, conflictingresults have been reported in a variety of species. We investigatedthe effects of testosterone manipulation on both cell-mediatedand humoral immunity in adult songbirds, European starlings(Sturnus vulgaris). Male and female starlings were wild-caught,housed in the laboratory, and implanted with either empty silasticcapsules or capsules containing testosterone. Six weeks after implantation, humoral immunity was assessed by injecting thebirds with a novel antigen, keyhole limpet hemocyanin, andmeasuring specific antibody responses 10 and 15 days latervia an enzyme-linked immunosorbant assay. Cell-mediated immunitywas assessed 7 weeks after implantation via intradermal injectionof the T-cell mitogen phytohemagglutinin into the wing web and measuring the degree of swelling 24 h later. Antibody responsesto antigenic challenge were significantly suppressed in testosterone-treatedfemales 10 days post-injection and in both sexes 15 days post-injection.Furthermore, there was a significant inverse relationship betweenindividual variability in antibody responsiveness and plasmatestosterone concentrations. Cell-mediated responses to phytohemagglutininstimulation were also significantly suppressed in testosterone-treatedmales compared to same-sex controls. Testosterone treatmentsignificantly increased plasma corticosterone concentrations compared to controls, and the possibility of this effect mediatingthe immunosuppressive effects of testosterone is discussed.The present study is among the first to demonstrate testosterone-inducedsuppression of both cell-mediated and humoral immunity in aspecies of songbird.     

Combination of CpG-oligodeoxynucleotides with recombinant ROP2 or GRA4 proteins induces protective immunity against Toxoplasma gondii infection

Synthetic oligodeoxynucleotides containing unmethylated CpG motifs (CpG-ODN) have been characterized as Th1-promoting immunopotentiators, an adjuvant activity desirable for vaccination against intracellular parasites like Toxoplasma gondii. In an attempt to find new antigen–adjuvant combinations that enhance the immunogenicity of antigen candidates for toxoplasma vaccines, we analyzed the extent of protection in mice immunized with ROP2 and GRA4 recombinant proteins when co-administered with CpG-ODN. Both GRA4 + CpG-ODN and ROP2 + CpG-ODN formulations were shown to induce a strong humoral Th1-biased response characterized by a high IgG_2a to IgG₁ antibody ratio. Both vaccination regimens led to increased secretion of IFN-γ and IL-10, and negligible amounts of IL-4, upon specific re-stimulation of spleen cells from these groups of mice. After a non-lethal challenge with tissue cysts of a moderately virulent strain, only the brains from mice vaccinated with ROP2 or GRA4 in combination with CpG-ODN showed a significant reduction (63% and 62%, respectively) in their parasite load compared to the controls. The rate of protection obtained with GRA4 + ROP2 + CpG-ODN resulted equivalent (66%) to those achieved with the single antigens plus CpG-ODN. Taken together, these results indicate that CpG-ODN is an important candidate adjuvant for use in potential multicomponent anti-T. gondii vaccines for animals and humans.     

Influence of serum donor and recipient mouse genotype on the passive transfer of protective immunity with serum against Nematospiroides dubius

Dobson C., Brindley P. J. and Sitepu P. 1982. Influence of serum donor and recipient mouse genotype on the passive transfer of protective immunity with serum against Nematospiroides dubius. International Journal for Parasitology12: 567–572. Different strains of serum donor mice showed variations in innate immunity to primary infections with Nematospiroides dubius. Different levels of anti-N, dubius antibodies were detected in sera from these mouse strains; there was no correlation between antibody titre and numbers of worms recovered. Serum from donor wild and six laboratory strains of mice protected female Quackenbush (Q) recipients against N. dubius infections; donor mouse strain influenced the degree of protection conferred and donor serum antibody titre related to the degree of stunting of worm growth in recipient mice. Five laboratory strains of mice developed different levels of protective immunity following multiple experimental infections with N. dubius. Antibody titres in these mice were strongly correlated with the percentage protection observed after 1–4 infections: Q and CBA mice produced more anti-N. dubius antibody and were better protected than DBA/2, BALB/c and C3H mice. However BALB/c, C3H and CBA mice attained similar anti-N. dubius antibody titres after a single infection with N. dubius but serum from BALB/c gave better protection when transferred to female Q recipients than that from the other two strains. This suggested qualitative differences in the protective antibodies in sera between mouse strains. Five mouse strains were passively immunized with a uniform dose of serum from female Q donors: DBA/2 female recipients showed the least, BALB/c and C3H females were intermediate, and Q and CBA female mice attained the greatest level of passive protection against N. dubius. A close positive correlation existed between the degree of actively acquired and the level of passively acquired protection between the five strains of mice.