DNA immunization with HIV-1 tat mutated in the trans activation domain induces humoral and cellular immune responses against wild-type Tat

Intramuscular immunization of mice with plasmids encoding two transdominant negative mutants of the HIV-1 Tat protein (Tat22 and Tat22/37) elicited a humoral response to wild-type Tat that is comparable to that induced by inoculation of wild-type tat DNA or Tat protein. The percentage of the responders and the Ab titers continued to increase after three additional DNA boosts and pretreatment with bupivacaine at the site of inoculation, without a significant difference (p > 0.05) among the three groups of mice immunized with mutant and wild-type tat genes. By utilizing synthetic peptides representing the amino acid sequence of Tat, one major B cell epitope was defined within the cysteine-rich domain of Tat. Anti-Tat IgG Abs directed against this epitope were found in mice immunized with all tat DNA constructs, whereas different Tat epitopes were detected in mice immunized with the Tat protein. Similarly, IgG2a was the predominant isotype in DNA-immunized mice, with both mutants and wild-type tat genes, as compared with protein immunization, which induced mostly IgG1 and IgG3. Sera from most immunized mice neutralized the effect of extracellular Tat in activating HIV-1 replication. A cellular response was also elicited as indicated by the proliferation of splenocytes when stimulated with wild-type Tat. These results indicate that the wild-type Tat Ag is recognized by Abs and T cells induced by DNA immunization with mutated tat genes, suggesting the possible use of these Tat transdominant mutants, lacking viral trans activation activity and capable of blocking wild-type Tat activity, in the development of an anti-HIV-1 vaccine.     

Intranasal immunization with recombinant vesicular stomatitis virus expressing murine cytomegalovirus glycoprotein B induces humoral and cellular immunity

Cytomegalovirus is a leading cause of morbidity and mortality among neonatal and immunocompromised patients. The use of vaccine prophylaxis continues to be an effective approach to reducing viral infections and their associated diseases. Murine cytomegalovirus (mCMV) has proven to be a valuable animal model in determining the efficacy of newly developed vaccine strategies in vivo. Live recombinant vesicular stomatitis viruses (rVSV) have successfully been used as vaccine vectors for several viruses to induce strong humoral and cellular immunity. We tested the ability of intranasal immunization with an rVSV expressing the major envelope protein of mCMV, glycoprotein B (gB), to protect against challenge with mCMV in a mouse model. rVSV-gB-infected cells showed strong cytoplasmic and cell surface expression of gB, and neutralizing antibodies to gB were present in mice after a single intranasal vaccination of VSV-gB. After challenge with mCMV, recovery of live virus and viral DNA was significantly reduced in immunized mice. In addition, primed splenocytes produced a CD8+ IFNgamma response to gB. The ability to induce an immune response to a gene product through mucosal vaccination with rVSV-gB represents a potentially effective approach to limiting CMV-induced disease.     

Recent insights into humoral and cellular immune responses against malaria

Effective immunity to malaria has been clearly demonstrated among individuals naturally exposed to malaria, and can be induced by experimental infections in animals and humans. The large number of malaria antigens has presented a major challenge to identifying protective responses and their targets, and it is likely that robust immunity is mediated by responses to multiple antigens. These include merozoite surface antigens and invasion ligands, variant antigens on the surface of parasitized red blood cells, in addition to sporozoite and liver-stage antigens. Immunity seems to require humoral and cellular immune components, probably in co-operation, although the relative importance of each remains unclear. This review summarizes recent progress towards understanding the targets and mechanisms that are important for mediating immunity to malaria.     

Immunostimulant adjuvant patch enhances humoral and cellular immune responses to DNA immunization

The focus of this report is on the development of an improved DNA immunization protocol, which takes advantage of the strengths of DNA immunization, as well as those associated with adjuvant delivered by transcutaneous immunostimulatory (IS) patches. Because transcutaneous delivery of adjuvants to the skin at the vaccination site has been shown to amplify the immune response to protein antigens, we hypothesized that the same IS patch when placed on the skin at the site of DNA injection could further enhance the immune response to a DNA influenza vaccine. We have combined an influenza DNA vaccine, hemagglutinin fused with three copies of complement C3d, to enhance uptake and antigen presentation, with an IS patch containing heat-labile enterotoxin from Escherichia coli. Coadministration of a potent adjuvant in IS patches placed on the skin at the site of DNA vaccination dramatically amplifies anti-influenza antibody immune response. Supplementing DNA vaccines with IS patches may be a particularly valuable strategy because DNA vaccines can be rapidly modified in response to mutations in pathogens, and individuals with compromised immune systems such as transplant patients and the elderly will benefit from the enhanced antibody response induced by the IS patches.     

A recombinant measles virus expressing hepatitis B virus surface antigen induces humoral immune responses in genetically modified mice

It has been shown previously that measles virus (MV) can be successfully used to express foreign proteins (M. Singh and M. A. Billeter, J. Gen. Virol. 80:101-106, 1998). To develop an inexpensive MV-based vaccine, we generated recombinant MVs that produce structural proteins of hepatitis B virus (HBV). A recombinant virus that expressed the HBV small surface antigen (HBsAg) was analyzed in terms of its replication characteristics, its genetic stability in cell culture, and its immunogenic potential in genetically modified mice. Although this virus showed a progression of replication slightly slower than that of the parental MV, it appeared to stably maintain the added genetic information; it uniformly expressed the appropriately glycosylated HBsAg after 10 serial passages. Genetically modified mice inoculated with this recombinant MV produced humoral immune responses against both HBsAg and MV proteins.     

Rectal immunization with rotavirus virus-like particles induces systemic and mucosal humoral immune responses and protects mice against rotavirus infection

To evaluate whether the rectal route of immunization may be used to provide appropriate protection against enteric pathogens such as rotaviruses (RV), we studied the antibody response and the protection induced by rectal immunization of mice with RV virus-like particles (VLP). For this purpose, 6-week-old BALBc mice were rectally immunized twice with RV 8-2/6/7-VLP derived from the bovine RV RF81 strain either alone or combined with various adjuvants including four toxins [cholera toxin (CT) and three attenuated Escherichia coli-derived heat-labile toxins (LTs), LT(R192G), LT(R72), and LT(K63)] and two Toll-like receptor-targeting adjuvants (CpG and resiquimod). Six weeks after the second immunization, mice were challenged with murine RV strain ECw. RV VLP administered alone were not immunogenic and did not protect mice against RV challenge. By contrast, RV VLP combined with any of the toxin adjuvants were immunogenic (mice developed significant titers of anti-RV immunoglobulin A [IgA] in both serum and feces and of anti-RV IgG in serum) and either efficiently induced complete protection of the mice (no detectable fecal virus shedding) or, for LT(K63), reduced the amount of fecal virus shedding after RV challenge. When combined with RV VLP, CpG and resiquimod failed to achieve protection, although CpG efficiently induced an antibody response to RV. These results support the consideration of the rectal route for the development of new immunization strategies against RV infection. Rectal delivery of a VLP-based vaccine might allow the use of adjuvants less toxic than, but as efficient as, CT.     

Trehalose-6-phosphate Phosphatase from Mycobacterium tuberculosis induces humoral and cellular immune responses

Trehalose-6-phosphate phosphatase is an enzyme strictly essential for the growth of mycobacteria. Subcellular fractionation of Mycobacterium tuberculosis and M. bovis bacillus Calmette-Guérin (BCG) located the trehalose-6-phosphate phosphatase in the cell wall and membrane fractions. Trehalose-6-phosphate phosphatase induced an increased Th1-type immune response in mice, characterized by an elevated level of interferon-gamma in antigen-stimulated splenocyte culture and a strong IgG2a antibody response. The trehalose-6-phosphate phosphatase was recognized by the sera of tuberculosis patients and BCG-vaccinated donors. The mycobacterial trehalose-6-phosphate phosphatase is an immunodominant antigen, and it may be a candidate for vaccine development for the control of tuberculosis.     

Interplay of cellular and humoral immune responses against BK virus in kidney transplant recipients with polyomavirus nephropathy

Reactivation of the polyomavirus BK (BKV) causes polyomavirus nephropathy (PVN) in kidney transplant (KTx) recipients and may lead to loss of the renal allograft. We have identified two HLA-A*0201-restricted nine-amino-acid cytotoxic T lymphocyte (CTL) epitopes of the BKV major capsid protein VP1, VP1(p44), and VP1(p108). Using tetramer staining assays, we showed that these epitopes were recognized by CTLs in 8 of 10 (VP1(p44)) and 5 of 10 (VP1(p108)) HLA-A*0201+ healthy individuals, while both epitopes elicited a CTL response in 10 of 10 KTx recipients with biopsy-proven PVN, although at variable levels. After in vitro stimulation with the respective peptides, CTLs directed against VP1(p44) were more abundant than against VP1(p108) in most healthy individuals, while the converse was true in KTx recipients with PVN, suggesting a shift in epitope immunodominance in the setting of active BKV infection. A strong CTL response in KTx recipients with PVN appeared to be associated with decreased BK viral load in blood and urine and low anti-BKV antibody titers, while a low or undetectable CTL response correlated with viral persistence and high anti-BKV antibody titers. These results suggest that this cellular immune response is present in most BKV-seropositive healthy individuals and plays an important role in the containment of BKV in KTx recipients with PVN. Interestingly, the BKV CTL epitopes bear striking homology with the recently described CTL epitopes of the other human polyomavirus JC (JCV), JCV VP1(p36) and VP1(p100). A high degree of epitope cross-recognition was present between BKV and corresponding JCV-specific CTLs, which indicates that the same population of cells is functionally effective against these two closely related viruses.     

Neonatal exposure to idiotype induces Schistosoma mansoni egg antigen-specific cellular and humoral immune responses.

Exposure of neonatal mice to appropriate, cross-reactive Id (CRI) preparations alters immune responsiveness, ameliorates pathology, and prolongs survival of animals upon subsequent Schistosoma mansoni infection. However, because schistosome infections profoundly affect host immunobiology, which responses are effected by neonatal Id exposure alone and which responses are influenced by infection is unclear. To directly examine the schistosome soluble egg Ag (SEA)-specific immune responses altered by CRI exposure, neonatal mice were injected with CRI-expressing (CRI+) SEA-specific Ab preparations, SEA-specific Abs that did not express CRI (CRI-), or normal mouse Ig. At 9 wk of age, only mice that were neonatally exposed to CRI+ anti-SEA Abs displayed significant SEA-specific IgG serum levels and spleen cell proliferative responses. SEA-stimulated spleen cells from these CRI+-exposed mice also produced IFN-gamma, although not at significantly higher levels than mice receiving CRI- Id or normal mouse Ig. If CRI+-exposed mice were also injected with SEA at 8 wk of age, the 9-wk IFN-gamma responses were significantly higher than those of the other neonatal injection groups. The presence of both CRI and anti-CRI in the sera of animals neonatally injected with CRI, but receiving no exposure to S. mansoni Ags or infection, suggested a functional idiotypic network led to these responses. These data demonstrate that appropriate idiotypic exposure induces B and T cell responsiveness to the Ag recognized by the Id and support the hypothesis that neonatal idiotypic exposure can be an important immunoregulatory factor in schistosomiasis.     

Immunization with hepatitis C virus-like particles induces humoral and cellular immune responses in nonhuman primates

We have previously reported the production of hepatitis C virus-like particles (HCV-LP) using a recombinant baculovirus containing the cDNA of the HCV structural proteins (core, E1, and E2). These particles resemble the putative HCV virions and are capable of inducing strong and broad humoral and cellular immune responses in mice. Here we present evidence on the immunogenicity of HCV-LP and the effects of novel adjuvant systems in a nonhuman primate model, the baboon. Three groups of four baboons were immunized with HCV-LP, HCV-LP and adjuvant AS01B (monophosphoryl lipid A and QS21), or HCV-LP and the combination of AS01B and CpG oligodeoxynucleotides 10105. After four immunizations over an 8-month period, all animals developed HCV-specific humoral and cellular immune responses including antibodies to HCV structural proteins and gamma interferon(+) (IFN-gamma(+))CD4(+) and IFN-gamma(+)CD8(+) T-cell responses. The immunogenicity of HCV-LP was only marginally enhanced by the use of adjuvants. The overall HCV-specific immune responses were broad and long lasting. Our results suggest that HCV-LP is a potent immunogen to induce HCV-specific humoral and cellular immune responses in primates and may be a promising approach to develop novel preventive and therapeutic modalities.     

Interactions between the cellular and humoral immune responses in Drosophila

Drosophila has highly efficient defenses against infection. These include both cellular immune responses, such as the phagocytosis of invading microorganisms, and humoral immune responses, such as the secretion of antimicrobial peptides into the hemolymph [1] [2]. These defense systems are thought to interact, but the nature and extent of these interactions is not known. Here we describe a method for inhibiting phagocytosis in Drosophila blood cells (hemocytes) by injecting polystyrene beads into the body cavity. This treatment does not in itself make a fly susceptible to Escherichia coli infection. However, when performed on flies carrying the mutation immune deficiency (imd), which affects the humoral immune response [3], the treatment results in a striking decrease in resistance to infection. We therefore carried out a sensitized genetic screen to identify immunocompromised mutants by co-injecting beads and E. coli. From this screen, we identified a new gene we have named red shirt and identified the caspase Dredd as a regulator of the Drosophila immune response. The observation that mutants with defects in the humoral immune response are further immunocompromised by blocking phagocytosis, and thus inhibiting the cellular immune response, shows that the Drosophila cellular and humoral immune responses act in concert to fight infection.     

Delivery of antigen to CD40 induces protective immune responses against tumors

Ligation of CD40 induces maturation of dendritic cells (DC) and could be a useful target for vaccines. In this study, we have constructed two types of Ab-based vaccine constructs that target mouse CD40. One type is a recombinant Ab with V regions specific for CD40 and has defined T cell epitopes inserted into its C region. The other type is a homodimer, each chain of which is composed of a targeting unit (single-chain fragment variable targeting CD40), a dimerization motif, and an antigenic unit. Such proteins bound CD40, stimulated maturation of DC, and enhanced primary and memory T cell responses. When delivered i.m. as naked DNA followed by electroporation, the vaccines induced T cell responses against MHC class II-restricted epitopes, Ab responses, and protection in two tumor models (myeloma and lymphoma). Two factors apparently contributed to these results: 1) agonistic ligation of CD40 and induction of DC maturation, and 2) delivery of Ag to APC and presentation on MHC class II molecules. These results highlight the importance of agonistic targeting of Ag to CD40 for induction of long-lasting and protective immune responses.     

Effect of ivermectin on the cellular and humoral immune responses of rabbits

The objective of this paper is to determine the effect of ivermectin administration on cell mediated (CMI) and humoral immunity (HI) of rabbits. CMI against dinitrochlorobenzene (DNCB) and sheep red blood cells (SRBC) in rabbits was determined by delayed-type hypersensitivity and macrophage engulfment assay (MEA), respectively; whereas, HI to Pasteurella multocida B2 vaccine and SRBC was determined by indirect haemagglutination assay (IHA) and Jerne hemolytic plaque formation assay (JHPFA), respectively. The rabbits were divided into four major groups (A through D) each subdivided into four sub-groups (1 through 4). Rabbits of group A served as vehicle control while those of groups B, C and D were treated with ivermectin at the dose rates of 200 microg/kg, 400 microg/kg and 600 microg/kg b.w., respectively. Cellular immunity was determined in sub-groups 1 and 2 through DNCB and MEA, respectively while HI was determined in sub-groups 3 and 4 through IHA and JHPFA, respectively. The skin sensitivity to DNCB at 24 and 48 h and macrophage engulfment of SRBC were highest (P>0.05) in rabbits administered with 600 microg/kg b.w. The highest geometric mean titers (14.00+/-0.31) and number of plaque forming units (1860+/-0.75) were found in rabbits that received ivermectin at a dose of 600 microg/kg b.w. followed, in order by the groups that received 400 microg/kg, 200 microg/kg b.w. and controls. Leukocyte counts were significantly higher in ivermectin-treated groups (C and D) than group A (vehicle control) and B (ivermectin at the rate of 200 microg/kg). A graded dose immune response suggested an immunopotentiating effect of ivermectin at higher doses.     

The porcine humoral immune response against pseudorabies virus specifically targets attachment sites on glycoprotein gC

High titers of virus-neutralizing antibodies directed against glycoprotein gC of Pseudorabies virus (PRV) (Suid herpesvirus 1) are generally observed in the serum of immunized pigs. A known function of the glycoprotein gC is to mediate attachment of PRV to target cells through distinct viral heparin-binding domains (HBDs). Therefore, it was suggested that the virus-neutralizing activity of anti-PRV sera is directed against HBDs on gC. To address this issue, sera with high virus-neutralizing activity against gC were used to characterize the anti-gC response. Epitope mapping demonstrated that amino acids of HBDs are part of an antigenic antibody binding domain which is located in the N-terminal part of gC. Binding of antibodies to this antigenic domain of gC was further shown to interfere with the viral attachment. Therefore, these results show that the viral HBDs are accessible targets for the humoral anti-PRV response even after tolerance induction against self-proteins, which utilize similar HBDs to promote host protein-protein interactions. The findings indicate that the host's immune system can specifically block the attachment function of PRV gC. Since HBDs promote the attachment of a number of herpesviruses, the design of future antiherpesvirus vaccines should aim to induce a humoral immune response that prevents HBD-mediated viral attachment.     

The enhancement of humoral and cellular immune responses by dimethyldioctadecylammonium bromide

Dimethyldioctadecylammonium bromide (DDA) produced marked enhancement of both cellular and humoral immune responses to SRBC when administered to mice intraperitoneally, or of cellular immunity when given subcutaneously. Stimulated cellular responses were seen as increased footpad swelling as a measure of delayed hypersensitivity and increased antigen-induced blastogenesis. Elevation of humoral response was reflected in increased numbers of splenic plaque-forming cells (PFC) and in circulating anti-SRBC antibody. Adjuvancy did not depend on addition of the lipid of DDA to antigen, as both humoral and cellular responses were enhanced whether DDA and SRBC were admixed or injected separately 4 hr apart intraperitoneally. DDA also enhanced the PFC response to the T-cell independent antigen TNP-LPS. The DDA effects are accompanied by macrophage activation, which may mediate at least in part the observed responses. DDA-activated macrophages exhibit fast spreading, are highly phagocytic, and elaborate significantly greater amounts of thymocyte mitogenic factor(s) than do normal resident peritoneal macrophages. This activation may effect the stimulation of antigen-specific primary lymphocyte responses by adjuvant and expansion of memory-cell populations which lead to the observed enhancement of secondary responses.     

表达EB病毒主要膜蛋白的非复制型重组痘苗病毒毒力及体液免疫反应

利用表达EBV GP350/220的非复制型重组痘苗病毒VMA△CK及复制性重组痘苗病毒VMA,注射乳鼠脑内,观察毒力。同时,用VMA△CK及VMA免疫Bal/c小鼠,经ELISA测定其特异性抗体水平。免疫血清用抗体中和EBV感染Raji细胞抑制产生早期抗原（NEA）法测定其中和抗体滴度。将免疫血清与P3HR-1细胞共同孵育后,测上清中EBV滴度以观察抗体体制EBV从P3HR-1细胞中释放效应。结果发现,VMA△CK毒力明显低于VMA,其LD50为4.5PFU/0.02ml,而VMA△CK的LD50大于10^6PFU/0.02ml。VMA△CK与VAM免疫血清中抗GP350/220抗体水平无明显差异,而初兔后抗痘苗病毒抗体水平VMA免疫组较VMA△CK免疫组高5倍左右。VMA△CK免疫组血清中和抗体水平没有明显差异。VMA△CK免疫血清稀释度与P3HR-1细胞培养上清中EBV滴度有剂量依赖关系。     

Human immune responses to synthetic peptides from the Epstein-Barr nuclear antigen

Humans infected with Epstein-Barr virus (EBV), the causative agent of infectious mononucleosis, develop antibodies against a nuclear antigen (EBNA) that is present in virally transformed B lymphocytes. The EBNA protein contains a unique glycine-alanine repeating sequence. We have synthesized peptides corresponding to various regions of the EBNA molecule within and near this sequence. Rabbit antibodies against the peptides within the sequence reacted directly with the EBNA protein, as detected by Western blotting. The sera of individuals with antibodies against Epstein-Barr virus contained abundant antibodies also reactive with one or several of the synthetic peptides within the sequence. Moreover, human antibodies against these simple peptides were induced specifically early in the course of infectious mononucleosis. When compared with normal controls, antibody levels to the glycine-alanine peptides were significantly higher in patients with rheumatoid arthritis and progressive systemic sclerosis, but not in patients with two other autoimmune diseases. These results document that i) antibodies against the peptides detect the EBNA protein, ii) humans infected with EBV produce high titers of antibodies reactive with these synthetic antigens, and iii) antibody titers against the peptides are abnormally elevated in certain autoimmune diseases.