Toxoplasma gondii rhomboid protein 1 (TgROM1) is a potential vaccine candidate against toxoplasmosis

Infection with the intracellular protozoan parasite Toxoplasma gondii causes serious public health problems and is of great economic importance worldwide. The rhomboid proteins which are responsible for adhesion and invasion of host cells have been suggested as vaccine candidates against toxoplasmosis. A DNA vaccine (pVAX-ROM1) encoding T. gondii rhomboid protein 1 (TgROM1) gene was constructed and the immune response and protective efficacy of this vaccine against lethal challenge in BALB/c mice were evaluated. The results indicated that specific antibody and lymphocyte proliferative responses were elicited in mice receiving pVAX-ROM1. The production levels of IFN-γ, IL-2, IL-4, and IL-10, as well as the percentage of CD4(+) cells in mice vaccinated with pVAX-ROM1 were significantly increased respectively, compared to controls receiving either pVAX1 alone or PBS. After lethal challenge, the mice immunized with pVAX-ROM1 showed an increased survival time compared with the mice in the controls. Our data suggested that a DNA vaccine pVAX-ROM1 encoding T. gondii rhomboid protein 1 triggered strong humoral and cellular responses, and prolonged survival time against T. gondii infection in BALB/c mice.     

共表达与牛疱疹病毒1型VP22融合的猪繁殖与呼吸综合征病毒E及M蛋白的重组伪狂犬病毒的构建及其免疫原性观察

为了研制猪繁殖与呼吸综合征病毒（PRRSV）基因工程疫苗，以伪狂犬病毒（PRV）gE基因缺失标志疫苗株TK^-／gE^-／LacZ^＋为病毒载体，通过同源重组，构建了共表达与牛疱疹病毒1型VP22（BHV-1 VP22）融合的PRRSV E及M蛋白的重组伪狂犬病毒（rPRV）TK^-／gE^-／VP22E^＋／VP22M^＋。经PCR、Southern blot、Western blot证实rPRV构建正确，并能表达与BHV-1 VP22融合的PRRSV E及M蛋白。rPRV在IBRS-2、PK-15细胞中的增殖滴度与PRV亲本株相比无显著差异，表明外源基因的插入不影响rPRV增殖。用该rPRV免疫BALB／c小鼠,检测免疫小鼠抗PRRSV中和抗体及脾淋巴细胞增殖反应，并与未融合VP22的单表达PRRSV E蛋白及共表达E及M蛋白的rPRV TK^-／gE^-／E^＋与TK^-／gE^-／E^＋／M^＋进行比较。结果显示TK^-／gE^-／VP22E^＋／VP22M^＋可诱导小鼠产生更好的体液与细胞免疫反应，BHV-1 VP22发挥了佐剂效应。本研究为研制安全、有效的猪繁殖与呼吸综合征-伪狂犬病二价基因工程疫苗奠定了基础。     

Evaluation of immune responses induced by SAG1 and MIC3 vaccine cocktails against Toxoplasma gondii

The aim of this study was to evaluate the immune responses of a SAG1 and MIC3 vaccine cocktail in BALB/c mice. Ninety-six BALB/c mice were randomly divided into eight groups, including three plasmid DNA vaccine groups (pcDNA-MIC3, pcDNA-SAG1, pcDNA-MIC3+pcDNA-SAG1), three recombinant pseudotype baculovirus vaccine groups (BV-G-MIC3, BV-G-SAG1, BV-G-SAG1+BV-G-MIC3) and two control groups (PBS and BV-G-EGFP). All groups were immunized intramuscularly twice at three-week intervals. The production of anti-Toxoplasma gondii lysate antigen (TLA) antibodies, lymphoproliferation, levels of IFN-γ, IL-4 and IL-10 and the survival time were monitored after vaccination. The results showed that immunization of BALB/c mice with MIC3 and SAG1 vaccines stimulated both the cellular and humoral immune responses with the production of anti-T. gondii TLA antibodies. The vaccine cocktails of pcDNA-MIC3+pcDNA-SAG1 or BV-G-SAG1+BV-G-MIC3 induced significantly higher immunogenicity than a single-gene vaccine (P<0.05). Splenocytes from the immunized mice significantly proliferated in response to the TLA and released interferon (IFN)-γ (P<0.05). However, the levels of IL-4 and IL-10 in the sera of the immunized mice were not significantly different from those of the controls (P>0.05). Immunization with the vaccine cocktail (BV-G-SAG1+BV-G-MIC3) in mice significantly prolonged survival (50%; P<0.05) against a lethal challenge of T. gondii (RH tachyzoites), while all mice in the other immunized groups and control groups died within 20 and 4 days post-infection, respectively. Furthermore, the recombinant pseudotype baculovirus vaccines induced better immunogenicity than the plasmid DNA vaccines (P<0.05). These results suggest that an excellent vector-mediated vaccine cocktail strategy might be used to develop a new generation of vaccines against T. gondii infection.     

以小鼠为模型评价重组伪狂犬病病毒rPRV-HA的免疫效力

以小鼠为动物模型，对此前构建的表达H3N2亚型猪流感病毒（SIV）血凝素（HA）基因的重组伪狂犬病病毒（rPRV-HA）进行了免疫效力评价。按每只10^5.0 TCID50 rPRV-HA的剂量通过滴鼻接种8周龄雌性BALB／c小鼠（n=60），同时设Bartha-K61免疫对照组（n=60）、非免疫攻毒对照组（n=20）和非免疫不攻毒对照组（n=10）。于免疫后不同时间分别从rPRV-HA免疫组和Bartha—K61免疫对照组随机剖杀一定数量的小鼠，其余小鼠于免疫后第28天用10^5.0 TCID50同亚型SIV毒株A／Swine／Heilongjiang／74／2000（H3N2）进行强毒攻击。攻毒后第4、7、14天分别剖杀小鼠，进行间接免疫荧光、病毒分离、血清学和病理组织学检测。结果表明，重组病毒主要分布于肺脏；免疫后14d起，从rPRV—HA免疫组及Bartha—K61免疫对照组均可检测到针对PRV的荧光抗体；从rPRV—HA免疫组可以检测到针对SIV的荧光抗体和血凝抑制抗体，而各对照组均呈阴性。攻毒后从rPRV—HA免疫组小鼠未分离到攻击病毒，血凝抑制抗体显著升高，病理变化显著轻于对照组，表明rPRV—HA免疫小鼠可以抵抗同亚型SIV的攻击，可以作为rPRV—HA免疫效力评价模型。     

Immune response and protective efficacy against homologous challenge in BALB/c mice vaccinated with DNA vaccine encoding Toxoplasma gondii actin depolymerizing factor gene

A DNA vaccine (pVAX1-TgADF) encoding Toxoplasma gondii actin depolymerizing factor (ADF) gene was constructed and the immune response and protective efficacy of this vaccine against homologous challenge in BALB/c mice were evaluated. High titers of specific antibody and increases in the percentage of CD4(+) and CD8(+) T lymphocyte cells were observed from BALB/c mice vaccinated with pVAX1-TgADF (P<0.05), when PBS group was used as control. The survival time of BALB/c mice in pVAX1-TgADF group was longer than those in control groups. The numbers of brain cysts in the experimental BALB/c mice immunized with pVAX1-TgADF reduced significantly compared with those in PBS group (P<0.05), and the rate of reduction could reach to around 42.8%. These results suggested that the DNA vaccine pVAX1-TgADF could generate specific humoral and cellular immune responses, prolong survival times, and reduce brain cysts load against T. gondii infection in BALB/c mice.     

乙型脑炎重组伪狂犬病病毒TK-/gG-/NS+1的安全性及免疫性

用含有日本乙型脑炎病毒 (SA14 - 14 - 2株 )非结构蛋白 NS1基因的重组伪狂犬病病毒 TK- / g G- / NS 1 免疫BAL B/ c小鼠和断奶仔猪。结果表明 ,该重组病毒对 BAL B/ c小鼠和断奶仔猪是安全的 ,免疫的 BAL B/ c小鼠能抵抗伪狂犬病病毒 (PRV )强毒 (Ea株 )的致死性攻击 ,免疫的断奶仔猪能产生乙型脑炎病毒 (JEV)特异性抗体和 JEV特异性 CTL 活性。     

Immunogenicity of a recombinant pseudorabies virus expressing ORF1-ORF2 fusion protein of porcine circovirus type 2

Porcine circovirus type 2 (PCV2) is associated with post-weaning multisystemic wasting syndrome (PMWS). Pseudorabies (PR) is also an important infectious disease in swine and sometimes co-infect with PCV2. An attenuated pseudorabies virus (PRV) has been successfully used as a vector for live viral vaccines. In this study, a recombinant PRV expressing ORF1-ORF2 fusion protein of PCV2 was constructed and its immunogenicity was tested in mice and pigs. The ORF1 and partial ORF2 gene of PCV2 Yu-A strain were amplified by PCR and inserted into a transfer vector. The recombinant transfer plasmid was co-transfected with the EcoRI digested genome of vector virus (PRV TK-/gE-/LacZ+) into IBRS-2 cells. The recombinant pseudorabies virus PRV-PCV2 was purified by plaque purification and identified by PCR and Southern blotting. Expression of the ORF1-ORF2 fusion protein by the recombinant PRV-PCV2 virus was demonstrated by Western blotting analysis. The growth properties of the recombinant virus in cells were similar to that of the parent vector virus. In animal experiments, PRV-PCV2 elicited strong anti-PRV and anti-PCV2 antibodies in Balb/c mice as indicated by PRV-neutralizing assay, anti-PCV2 ELISA and PCV2 specific lymphocyte proliferation assay, respectively. And PRV-PCV2 immunization protected mice against a lethal challenge of a virulent PRV Ea strain. In pigs, PRV-PCV2 elicited significant immune response towards PRV and PCV2 as indicated by PRV-ELISA, PRV neutralizing assay and PCV2 specific lymphocyte proliferation assay, respectively. This is a first step toward the development of a potential candidate divalent vaccine against PRV and PCV2 infections.     

A fusion protein of IgG fc and mouse-derived antigen on the surface of pseudorabies virus particles does not accelerate production of harmful auto-reactive antibodies

Previously we reported that immunization with pseudorabies virus (PRV), harboring chimeric Fc on the surface of the virus particles (PRV/Fc), induced higher immune responses than normal PRV particles. The chimeric Fc was fused with mouse transferrin receptor of transmembrane domain (mTR) and the Fc region of immunoglobulin G1. Since it has been reported that some chimeric protein of Fc and self-antigen induce auto-reactive antibodies, in this present study, we examined whether PRV/Fc induces auto-reactive antibodies that react with mTR. PRV/Fc immunized mice produced higher levels of anti-PRV antibodies and antibodies that reacted with mouse-derived 3T3/A31 cells (A31 cell), compared to normal PRV immunized mice. However, antibodies that reacted with mTR in A31 cells were not detected in both Western blot analyses and indirect immunofluorescence assay. The antibodies reacted with an antigen of approximately 16 kDa in A31 cells, but this antigen has a different molecular mass from that of mTR. The antibody also reacted with the antigen of approximately 16 kDa in RK13 cells in which the virus had been propagated. In addition, antibodies induced by immunization with normal PRV also reacted with the same antigen in A31 and RK13 cells. Moreover, neither kidney disorders, in which high levels of mTR were expressed, nor clinical symptoms of autoimmune diseases were observed in mice immunized with either PRV or PRV/Fc. These results indicated that the antibodies were not induced by mTR-Fc, but were instead induced by trace amounts of RK13 derived antigens contained in PRV or PRV/Fc preparations, and cross-reacted with equivalent molecules in mouse derived A31 cells. Therefore, this study confirmed that immunization with PRV/Fc did not induce harmful auto-reactive antibodies.     

Vaccine-induced T cell-mediated immunity plays a critical role in early protection against pseudorabies virus (suid herpes virus type 1) infection in pigs

The aim of our study was to evaluate the relative importance of antibody and T cell-mediated immunity in protection against pseudorabies virus (suid herpes virus type 1) infection in pigs. We induced different levels of immune responses by using: (1) a modified live vaccine; (2) the same modified live vaccine with an oil-in-water (o/w) adjuvant; (3) an inactivated vaccine; and (4) the same inactivated vaccine with an o/w adjuvant. Subsequently, we challenged pigs with virulent pseudorabies virus (PRV). We demonstrated that best-protected pigs stood out by maintaining strong T cell-mediated immune (CMI) responses after challenge. Of the immune parameters tested, protection against virus shedding was correlated best with the magnitude of the IFN-gamma response of in vitro re-stimulated peripheral blood mononuclear cells (PBMC) with an additional role for PRV-specific IgG2 antibodies. The use of an o/w adjuvant resulted in higher antibody and CMI responses, in particular with an increased frequency of memory T helper blast cells of in vitro re-stimulated PBMC. However, this adjuvant-induced enhancement of the immune response had a limited additional effect on the efficacy of inactivated vaccines. This study suggests a major contribution of the CMI response in early protection against PRV infection and that PRV-induced IFN-gamma responses may serve as a suitable indicator for assessing the immune status of vaccinated pigs.     

Prime-boost immunization using alphavirus replicon and adenovirus vectored vaccines induces enhanced immune responses against classical swine fever virus in mice

This study was designed to evaluate the prime-boost vaccination regimens as a novel immunization strategy for DNA vaccine against classical swine fever virus (CSFV). BALB/c mice were primed with the alphavirus replicon-vectored DNA vaccine pSFV1CS-E2-UL49 encoding the E2 protein of CSFV fused with the UL49 gene encoding the transduction protein VP22 of pseudorabies virus, followed by either homologous boosting with pSFV1CS-E2-UL49 or heterologous boosting with the recombinant adenovirus rAdV-E2 expressing the E2 protein or with the baculovirus-produced recombinant E2 protein (rE2) in adjuvant. The humoral and cell-mediated immune responses following prime-boost vaccination were assessed. The results showed that: (1) boosting with either rAdV-E2 or rE2 elicited high-level antibodies, whereas homologous boosting with pSFV1CS-E2-UL49 elicited low-level antibodies (below positive threshold); (2) heterologous boosting with rAdV-E2 resulted in stronger CD8⁺ and CD4⁺ T cells proliferation responses and higher stimulation indexes; and (3) heterologous boosting with rAdV-E2 induced more IFN-γ production. These results support the notion that a regimen of DNA prime-recombinant adenovirus boost enhances humoral and cell-mediated immune responses, and the DNA prime-protein boost regimen enhances humoral immune responses.     

A recombinant pseudorabies virus encoding the HA gene from H3N2 subtype swine influenza virus protects mice from virulent challenge

The hemagglutinin (HA) gene of A/Swine/Inner Mogolian/547/2001 (H3N2) swine influenza virus (SIV) was recombined into the genome of pseudorabies virus (PRV) Bartha-K61 vaccine strain, generating a recombinant PRV expressing the HA gene, designated as rPRV-HA. One group of 15 mice was inoculated intranasally (i.n.) with 10(5.0) PFU of rPRV-HA, and another two control groups of mice (15 mice per group) were mock-inoculated or inoculated with Bartha-K61. Mice inoculated with rPRV-HA developed hemagglutination inhibition antibodies 3 weeks post-inoculation. Twenty-eight days post-inoculation, all mice were challenged i.n. with 10(5.0) TCID50 of A/Swine/Heilongjiang/74/2000 (H3N2). No challenge virus was isolated from vaccinated mice, and mild pathological lesions were observed only in lungs following challenge. The results demonstrate that the recombinant rPRV-HA expressing the HA gene from H3N2 SIV can protect mice from heterologous virulent challenge, and may represent a candidate vaccine against SIV.     

Gene immunization of mice with plasmid DNA expressing rabies virus glycoprotein

Gene immunization can be an effective vaccine strategy eliciting both humoral and cell-mediated immune responses. We constructed plasmid vectors expressing the full-length Vnukovo-32 rabies virus glycoprotein G under the control of CMV IE promoter and enhancer, adenovirus tripartite leader sequences and poly A signal of SV40. The gene vaccines were evaluated for the ability to elicit neutralizing antibodies and to protect BALB/c mice against lethal rabies virus challenge. First, mice were injected intramuscularly (i.m.) into the left hind leg and by the intradermoplantar (i.d.p.) route with equal amounts of plasmid DNA (0.25-0.1 mg). Two weeks later, immunization was boosted with an additional dose of the DNA. The immunized mice were challenged by intracerebral (i.c.) inoculation of CVS-27 (10-50 LD50) rabies virus. All mice produced anti-rabies virus neutralizing antibodies with a titre of > or = 1:45 after immunization with 0.1-0.4 mg of DNA. In challenge experiments, 83 to 91.6% protection was observed. These results confirm that a DNA vaccine could be a simple and effective solution for preventing the spread of rabies.     

Preparation and Identification of Monoclonal Antibody against Min-A Strain of Pseudorabies Virus (PRV)

With purified pseudorabies virus (PRV) to immune BALB/c mice, spleen cells from imunized mice were fused with SP2/0 myeloma cells by application of lymphocyte hybridoma technique, followed by double antibody sandwich ELISA screening, four times cloning by limiting dilution method to obtain two stable secreting anti-PRV monoclonal antibody hybridoma cell lines, 2C6E6 and 3D5F1.After identification, these two monoclonal antibodies belonged to IgG1 and IgG2a subtypes, respectively, the average number of chromosomes of hybridoma cells was 84, ELISA titers of these two hybridoma cell culture supernatants and mouse ascites monoclonal antibodies were 1:512 and 1:1 638 400, 1:1 024 and 1:819 200.These two monoclonal antibodies showed no cross-reaction with classical swine fever virus, porcine reproductive and respiratory syhdrome virus and porcine parvovirus, which indicated that they had high specificity.The hydridoma cells could passage for 30 generations which could still secrete monoclonal antibody against PRV, which indicated that these two monoclonal antibodies had good stability.The results in the assay laid the foundation for establishing rapid diagnostic methods of PRV.     

猪伪狂犬病灭活疫苗(HB-J株)对兔与猪免疫攻毒保护平行关系的研究试验

用研制的连续3批猪伪狂犬病灭活疫苗(HB-J株)分别以不同剂量免疫健康兔和断奶仔猪,检测其免疫28 d后的血清抗体,采用血清中和试验法测定血清中和指数,并对免疫28 d后的兔和断奶仔猪分别进行攻毒,统计各组兔和断奶仔猪免疫后攻毒保护率。结果表明,兔免疫28 d后的血清抗体中和指数为794～1258时保护率为60%～80%,血清抗体中和指数≥1479时可获得100%保护;仔猪免疫28 d后的血清抗体中和指数为229～269时保护率为60%～80%,血清抗体中和指数≥331时可获得100%保护。兔与仔猪对猪伪狂犬病灭活疫苗(HB-J株)均产生良好的免疫应答反应,抗体值较高者获得保护率相对较高,兔与猪免疫与攻毒保护呈现平行关系。     

Ginsenoside Rg1 enhances immune response induced by recombinant Toxoplasma gondii SAG1 antigen

Ginsenoside, the most important component isolated from Panax ginseng, exhibits a variety of biological activities. Particularly, ginsenoside Rg1 is known to have immune-modulating activities such as increase of immune activity of T helper (Th) cells. In the present study, we evaluated the immunomodulatory potentials of the Rg1 at three dose levels on the cellular and humoral immune responses of ICR mice against T. gondii recombinant surface antigen 1 (rSAG1). ICR mice were immunized subcutaneously with 50 μg Rg1 alone, 100 μg rSAG1 alone or with 100 μg rSAG1 dissolved in saline containing ginsenoside Rg1 (10 μg, 50 μg or 100 μg). After immunization, we evaluated the immune response using lymphoproliferative assay, cytokine and antibody measurements, and the survival times of mice challenged lethally. The results showed that the groups immunized with rSAG1 and Rg1 (50 μg, 100 μg) developed a high level of specific antibody responses against T. gondii rSAG1, a strong lymphoproliferative response, and significant levels of cytokine production, compared with the other groups. After lethal challenge, the mice immunized with the rSAG1 and Rg1 (50 μg, 100 μg) showed a significantly increased survival time compared with control mice which died within 6 days of challenge. Our data demonstrate that by addition of ginsenoside Rg1, the rSAG1 triggered a stronger humoral and cellular response against T. gondii, and that Rg1 is a promising vaccine adjuvant against toxoplasmosis, worth further development.     

Evaluation in swine of a subunit vaccine against pseudorabies

A subunit vaccine against pseudorabies virus (PRV) was prepared by treating a mixture of pelleted virions and infected cells with the nonionic detergent Nonidet P-40 and emulsifying the extracted proteins incomplete Freund's adjuvant. Three 7-week-old pigs without antibodies against PRV were given 2 IM doses of this vaccine 3 weeks apart. Thirty days after the 2nd vaccination, 10(6) median tissue culture infective doses (TCID50) of a virulent strain of PRV were administered intranasally. Tonsillar and nasal swabs were collected daily between 2 and 10 days after challenge exposure. The pigs vaccinated with the subunit vaccine were not found to shed virulent PRV. Two groups of five 7-week-old pigs vaccinated with commercially available vaccines, either live-modified or inactivated virus, and subsequently exposed to 10(6) TCID50 of virulent PRV, shed virulent virus for up to 8 days. The subunit vaccine induced significantly higher virus-neutralizing antibody titers than either the live-modified or inactivated virus vaccine.     

Survival and immunization of raccoons after exposure to pseudorabies (Aujeszky's disease) virus gene-deleted vaccines

In a controlled experiment, 16 wild-trapped raccoons were exposed to 1 of 2 genetically modified live pseudorabies virus (PRV) vaccines used in swine. One vaccine had genes deleted for thymidine kinase (TK(-)) and glycoprotein G (gG(-)); the other had an additional deletion for glycoprotein E (gE(-)). These vaccines were administered orally and intranasally at four dose levels: 10(3), 10(4), 10(5), and 10(6) TCID(50). The 21 days survival rate was 37.5% for the gG(-)TK(-) vaccine; all of the survivors developed antibodies to PRV. All animals receiving the gG(-)gE(-)TK(-) vaccine survived; 75% (all except the lowest dose) developed anti-PRV antibodies. Survivors were challenged intranasally with a 3.2x10(3) TCID(50) dose of the virulent wildtype PRV Shope strain. Two of the remaining three gG(-)TK(-) vaccinated raccoons survived the challenge; for the gG(-)gE(-)TK(-) vaccine, the survival rate was 50% (4/8). The raccoons with higher vaccine-induced antibody titers were more likely to survive the challenge with the virulent PRV; there was a 100% mortality rate for raccoons lacking detectable anti-PRV antibodies. This experiment indicates that exposure of raccoons to modified live gene-deleted PRV vaccines may result in an immune response, and that this immunity provides some protection against exposure to virulent virus.     

Immunogenic properties of a bovine herpesvirus-1 (BHV-1) recombinant expressing major pseudorabies virus (PrV) glycoproteins in combination

A recombinant bovine herpesvirus type 1 (BHV-1), designated BHV-1/TF17-1, which expresses pseudorabies virus (PrV) glycoproteins gB, gC, gD, gE and gI in combination was constructed. To test the protective immunity, 10 mice were inoculated with BHV-1/TF17-1 and three weeks later 10 mice were intraperitoneally (i.p.) challenged with 20 LD50 virulent PrV (YS-81). BHV-1/TF17-1 protected all the mice from the PrV lethal challenge while all the control mice died in around 3 days. Mice vaccinated with BHV-1/TF17-1 acquired high PrV-neutralizing antibody titers and demonstrated strong delayed type hypersensitivity responses and moderate in vitro lymphocyte proliferative responses to PrV antigen. Since the major PrV glycoproteins were integrated into virions (probably into viral envelope), BHV-1/17-1 was neutralized with anti-PrV antiserum. However, the susceptibility of BHV-1/TF17-1 to anti-PrV antiserum is 2- to 4-fold lower than that of PrV vaccine lines. Our results demonstrated the possibility of BHV-1/17-1 as a vaccine to protect piglets from Audjesky's disease where maternal antibodies against PrV interfere attenuated live PrV vaccines.     

Protection of mice against Brucella abortus infection by inoculation with monoclonal antibodies recognizing Brucella O-antigen

Monoclonal antibodies recognizing the O-polysaccharide portion of Brucella abortus strain 2308 provided BALB/c mice with passive protection against challenge exposure with the homologous strain. Numbers of colony-forming organisms in the spleen were reduced by IgM and IgG monoclonal antibodies. Active immunization of mice, using B abortus 2308S lipopolysaccharide, resulted in production of IgM antibody at 14 days. Clearance of organisms in the actively immunized mice after challenge exposure at 14 days was nearly identical to that in passively immunized mice. Mice either passively or actively immunized were effectively protected from 0 to 28 days. Bacterial colonization of the spleen was observed to increase in both groups of mice at 56 days and indicated that humoral responses were effective in eliminating the organism in the early stages of infection, but other immune mechanisms were necessary for protection of mice in the later stage of infection with virulent strains of B abortus.     

人参茎叶总皂苷联合亚硒酸钠对猪伪狂犬病灭活疫苗免疫的增强作用

为了探讨人参茎叶总皂苷(ginseng stem-leaf saponins,GSLS)联合亚硒酸钠(Na2SeO3,简称Se)对伪狂犬病病毒(PRV)灭活疫苗免疫的增强作用,本试验给小鼠口服GSLS后,接种添加了Se的PRV灭活疫苗,并检测免疫后小鼠血清中PRV gB抗体及其亚类(IgG1和IgG2a)水平、淋巴细胞...