Modulation by colostrum-acquired maternal antibodies of systemic and mucosal antibody responses to rotavirus in calves experimentally challenged with bovine rotavirus

The effect of colostral maternal antibodies (Abs), acquired via colostrum, on passive protection and development of systemic and mucosal immune responses against rotavirus was evaluated in neonatal calves. Colostrum-deprived (CD) calves, or calves receiving one dose of pooled control colostrum (CC) or immune colostrum (IC), containing an IgG1 titer to bovine rotavirus (BRV) of 1:16,384 or 1:262,144, respectively, were orally inoculated with 105.5 FFU of IND (P[5]G6) BRV at 2 days of age. Calves were monitored daily for diarrhea, virus shedding and anti-BRV Abs in feces by ELISA. Anti-rotavirus Ab titers in serum were evaluated weekly by isotype-specific ELISA and virus neutralization (VN). At 21 days post-inoculation (dpi), all animals were euthanized and the number of anti-BRV antibody secreting cells (ASC) in intestinal and systemic lymphoid tissues were evaluated by ELISPOT. After colostrum intake, IC calves had significantly higher IgG1 serum titers (GMT=28,526) than CC (GMT=1195) or CD calves (GMT<4). After BRV inoculation, all animals became infected with a mean duration of virus shedding between 6 and 10 days. However, IC calves had significantly fewer days of diarrhea (0.8 days) compared to CD and CC calves (11 and 7 days, respectively). In both groups receiving colostrum there was a delay in the onset of diarrhea and virus shedding associated with IgG1 in feces. In serum and feces, CD and CC calves had peak anti-BRV IgM titers at 7 dpi, but IgA and IgG1 responses were significantly lower in CC calves. Antibody titers detected in serum and feces were associated with circulation of ASC of the same isotype in blood. The IC calves had only an IgM response in feces. At 21 dpi, anti-BRV ASC responses were observed in all analyzed tissues of the three groups, except bone marrow. The intestine was the main site of ASC response against BRV and highest IgA ASC numbers. There was an inverse relationship between passive IgG1 titers and magnitude of ASC responses, with fewer IgG1 ASC in CC calves and significantly lower ASC numbers of all isotypes in IC calves. Thus, passive anti-BRV IgG1 negatively affects active immune responses in a dose-dependent manner. In ileal Peyer's patches, IgM ASC predominated in calves receiving colostrum; IgG1 ASC predominated in CD calves. The presence in IC calves of IgG1 in feces in the absence of an IgG1 ASC response is consistent with the transfer of serum IgG1 back into the gut contributing to the protection of the intestinal mucosa.     

Antibody isotype responses in the serum and respiratory tract to primary and secondary infections with equine influenza virus (H3N8)

Serum antibody (IgGab, IgM and IgA) responses to primary and secondary infection with influenza A/equine/Newmarket/79 (H3N8) by nebulised aerosol were compared with local (nasopharyngeal and tracheal) antibody responses in ponies. Circulating IgGab antibody was of long duration after primary infection, whereas IgM responses were short-lived after both primary and secondary infections. The antigenic stimulation of secondary infection with equine influenza was sufficient to induce elevations of serum IgM and IgA in the presence of high levels of circulating IgGab. These results support the potential of virus-specific IgM measurement for the detection of recent exposure to virus in horses which have high levels of circulating IgGab. Unlike serum IgGab, nasal and tracheal wash antibody of this isotype did not show long duration after primary infection, but local antibody memory was demonstrated by anamnestic responses on rechallenge. Nasopharyngeal IgA developed later than IgGab and IgM, and was more durable.     

Analysis of the quality of protection induced by a porcine influenza A vaccine to challenge with an H3N2 virus

Antigenic drift of swine influenza A (H3N2) viruses away from the human A/Port Chalmers/1/73 (H3N2) strain, used in current commercial swine influenza vaccines, has been demonstrated in The Netherlands and Belgium. Therefore, replacement of this human strain by a more recent swine H3N2 isolate has to be considered. In this study, the efficacy of a current commercial swine influenza vaccine to protect pigs against a recent Dutch field strain (A/Sw/Oedenrode/96) was assessed. To evaluate the level of protection induced by the vaccine it was compared with the optimal protection induced by a previous homologous infection. Development of fever, virus excretion, and viral transmission to unchallenged group mates were determined to evaluate protection. The vaccine appeared efficacious in the experiment because it was able to prevent fever and virus transmission to the unchallenged group mates. Nevertheless, the protection conferred by the vaccine was sub-optimal because vaccinated pigs excreted influenza virus for a short period of time after challenge, whereas naturally immune pigs appeared completely protected. The immune response was monitored, to investigate why the vaccine conferred a sub-optimal protection. The haemagglutination inhibiting and virus neutralising antibody responses in sera, the nucleoprotein-specific IgM, IgG, and IgA antibody responses in sera and nasal secretions and the influenza-specific lymphoproliferation responses in the blood were studied. Vaccinated pigs developed the same or higher serum haemagglutination inhibiting, virus neutralising, and nucleoprotein-specific IgG antibody titres as infected pigs but lower nasal IgA titres and lymphoproliferation responses. The lower mucosal and cell-mediated immune responses may explain why protection after vaccination was sub-optimal.     

Effects of DNA dose,route of vaccination,and coadministration of porcine interleukin-6 DNA on results of DNA vaccination against influenza virus infection in pigs

OBJECTIVE: To examine the effects of DNA dose, site of vaccination, and coadministration of a cytokine DNA adjuvant on efficacy of H1-subtype swine influenza virus hemagglutinin (HA) DNA vaccination of pigs. ANIMALS: 24 eight-week-old mixed-breed pigs. PROCEDURE: 2 doses of DNA were administered 27 days apart by use of a particle-mediated delivery system (gene gun). Different doses of HA DNA and different sites of DNA administration (skin, tongue) were studied, as was coadministration of porcine interleukin-6 (pIL-6) DNA as an adjuvant. Concentrations of virus-specific serum and nasal mucosal antibodies were measured throughout the experiment, and protective immunity was assessed after intranasal challenge with homologous H1N1 swine influenza virus. RESULTS: Increasing the dose of HA DNA, but not coadministration of pIL6 DNA, significantly enhanced virus-specific serum antibody responses. Pigs that received DNA on the ventral surface of the tongue stopped shedding virus 1 day sooner than pigs vaccinated in the skin of the ventral portion of the abdomen, but none of the vaccinated pigs developed detectable virus-specific antibodies in nasal secretions prior to challenge, nor were they protected from challenge exposure. Vaccinated pigs developed high virus-specific antibody concentrations after exposure to the challenge virus. CONCLUSIONS AND CLINICAL RELEVANCE: Co-administration of pIL-6 DNA did not significantly enhance immune responses to HA DNA vaccination or protection from challenge exposure. However, HA DNA vaccination of pigs, with or without coadministration of pIL-6 DNA, induced strong priming of the humoral immune system.     

Mucosal and systemic isotype-specific antibody responses and protection in conventional pigs exposed to virulent or attenuated porcine epidemic diarrhoea virus

Eleven-day-old conventionally reared piglets were inoculated orally with two different doses of the cell-culture adapted strain CV-777 of the porcine epidemic diarrhoea virus (PEDV) or the virulent isolate of the same strain and challenged with the same virulent PEDV 3 weeks later. Pigs inoculated with the two doses of the attenuated virus did not show any typical sign of the disease, and virus shedding was not frequent. In contrast, 31% of pigs exposed to the virulent PEDV developed diarrhoea and virus shedding was demonstrated in 100%. At different postinoculation day (PID) and postchallenge day (PCD) virus-specific antibody-secreting cells (ASC) in gut associated lymphoid tissues (duodenum and ileum lamina propria and mesenteric lymph nodes) and systemic locations (blood and spleen) were assessed by enzyme-linked immunospot (ELISPOT). Only a small response was detected in the groups inoculated with attenuated PEDV, whereas in the group previously exposed to the virulent virus on PID 21 a large number of IgG and IgA ASC was detected. Isotype-specific antibody responses in serum were investigated by ELISA. IgG responses were detected in all groups, although the highest response corresponded to the group inoculated with virulent virus and only this group showed an IgA response. The pigs exposed to virulent PEDV were completely protected against the challenge with a higher dose of the same virulent virus on PID 21 and none of them shed the virus. The pigs inoculated with the attenuated strain were partially protected against the challenge, and 25% of the low dose- and 50% of the high dose-exposed pigs did not shed virus after challenge. All the pigs from a control group, not previously exposed to the virus, excreted the virus in faeces. A strong positive correlation was established between protection and the ASC responses detected in gut associated lymphoid tissues and blood at the challenge day and also between protection and serum isotype-specific antibody titers on that day. In addition, the IgA and IgG ASC responses detected in the blood on PID 21 also correlated with the responses found in the gut associated lymphoid tissues. The ASC and serum antibody responses after the challenge corresponded to a secondary immune response in the groups inoculated with attenuated virus, whereas a primary response was evident in the control group. No increase was seen in any of the parameters studied in the pigs inoculated with virulent PEDV.     

Antigen dose modulates the immunoglobulin isotype responses of pigs against intramuscularly administered F4-fimbriae

Parenteral immunisation normally induces a systemic antibody response characterised by high IgG and low IgA responses. In the present study, the effect of different doses of F4-fimbriae on the isotype-specific antibody response after intramuscular immunisation was studied in pigs. Pigs were injected twice with a 9 weeks interval with either 1, 0.1 or 0.01 mg of F4-ETEC fimbriae. The dose of 1mg F4 induced significantly lower primary F4-specific IgG and IgM responses than the doses of 0.1 and 0.01 mg F4, but primed for an enhanced F4-specific IgM serum antibody response after the booster immunisation. Furthermore, the dose of 0.1mg induced the highest F4-specific IgA serum response which was significantly higher than after injection with 0.01 and 1mg F4. Moreover, both lower doses (0.1 and 0.01 mg) showed a higher number of F4-specific IgA and IgG antibody secreting cells (ASC) in the local draining lymph nodes of the pigs. This study demonstrated that low doses of purified F4-ETEC fimbriae, especially the 0.1mg dose, are optimal for inducing F4-specific IgA responses after IM immunisation.     

Measurement of isotype-specific antibody responses to Aujeszky's disease virus in sera and mucosal secretions of pigs.

Enzyme-linked immunosorbent assays (ELISAs) for the detection of porcine IgM, IgA, IgG1 and IgG2 antibodies directed against Aujeszky's disease virus (ADV) are described. ADV-specific IgA and IgM were detected in an antibody capture assay, and ADV-specific IgG1 and IgG2 were detected in an indirect double antibody sandwich assay. A selected set of samples was tested in the four ELISAs and in a 24 h virus neutralization assay. Comparison of the results showed that the ELISAs were isotype-specific, sensitive, and reproducible. Samples with ADV antibody of one isotype showed that ADV-specific IgG1, IgG2 and IgM were able to neutralize the virus in vitro. In vitro neutralization of virus can be enhanced by complement. ADV-specific IgA neutralized virus only weakly. ADV-infected cells activated complement in the absence of antibody. Specific IgG2 and IgM enhanced complement activation. Analysis of the time course of antibody responses after infection or vaccination revealed that the isotype-specific ELISAs are suitable to study the humoral antibody response of pigs to the virus in mucosal secretions. Wild-type virus (strain NIA-3) and an attenuated vaccine strain (Bartha) administered intranasally induced mucosal IgM and IgA responses to the virus. In contrast, a killed vaccine (Nobivac) administered intramuscularly induced only weak mucosal IgM responses. The attenuated vaccine strain primed for a mucosal IgA memory response evoked upon challenge infection with wild-type virus.     

The use of a systemic prime/mucosal boost strategy with an equine influenza ISCOM vaccine to induce protective immunity in horses

In horses, natural infection confers long lasting protective immunity characterised by mucosal IgA and humoral IgGa and IgGb responses. In order to investigate the potential of locally administered vaccine to induce a protective IgA response, responses generated by vaccination with an immunostimulating complex (ISCOM)-based vaccine for equine influenza (EQUIP F) containing A/eq/Newmarket/77 (H7N7), A/eq/Borl?nge/91 (H3N8) and A/eq/Kentucky/98 (H3N8) using a systemic prime/mucosal boost strategy were studied. Seven ponies in the vaccine group received EQUIP F vaccine intranasally 6 weeks after an initial intramuscular immunisation. Following intranasal boosting a transient increase in virus-specific IgA was detected in nasal wash secretions. Aerosol challenge with the A/eq/Newmarket/1/93 reference strain 4 weeks after the intranasal booster resulted in clinical signs of infection and viral shedding in seven of seven influenza-naive control animals whereas the seven vaccinated ponies had statistically significantly reduced clinical signs and duration of virus excretion. Furthermore, following this challenge, significantly enhanced levels of virus-specific IgA were detected in the nasal washes from vaccinated ponies compared with the unvaccinated control animals. These data indicate that the intranasal administration of EQUIP F vaccine primes the mucosal system for an enhanced IgA response following exposure to live influenza virus.     

Brucella abortus-specific immunoglobulin in isotypes in serum and vaginal mucus from cattle vaccinated with strain 19 and challenge exposed with virulent strain 2308

The immunoglobulins (IgG1, IgG2, IgM, and IgA) of the Brucella-specific antibody response of 69 crossbred beef heifers were studied after Brucella abortus strain 19 vaccination and strain 2308 challenge exposure. The immunoglobulin isotype responses in serum and vaginal mucus were measured by use of fluorescent immunoassay. Serum antibody responses were detected also by 3 standard serologic tests (complement fixation [CF], Rivanol precipitation, and the CARD test] and 2 primary bindings assays that detect IgG antibodies. One month after vaccination, mean antibody titers for all immunoglobulin isotypes were higher for vaccinated cattle (n = 46) than for nonvaccinated controls (n = 23). After vaccination, IgA antibody responses in vaccinated cattle were only 2-fold higher than those for controls, whereas IgG1, IgG2, and IgM antibody responses were 3- to 90-fold greater than those for controls. Measurement of IgA antibody responses classified 21 of 39 vaccinates as seropositive after vaccination, whereas the other isotypes classified 28 or 34 cattle as seropositive. Three months after challenge exposure, the mean antibody responses for each isotype were higher in cattle that aborted or were culture positive than in cattle that did not abort and were culture negative. Although IgG1, IgG2, and IgM antibody titers were each of benefit in identifying B abortus-infected cattle, it did not appear that the magnitude of the antibody responses provided sufficient discrimination between S19-vaccinated cattle and S2308 challenge-exposed cattle. Serum IgA antibody responses were 10-fold higher after challenge exposure than after vaccination and may be a response to mucosal infection with the virulent organism.(ABSTRACT TRUNCATED AT 250 WORDS)     

Detection of antibodies against African swine fever virus using infected monolayers and monoclonal antibodies

Three monoclonal antibodies, specific for porcine IgG, IgM and IgA, were used to develop isotype-specific immunoperoxidase monolayer assays for the detection of antibodies against African swine fever virus. A mixture of anti-IgM and anti-IgG monoclonal antibodies was used in an assay designed for screening sera. This test was compared with a commercially available ELISA by using experimental sera and field sera obtained after an outbreak of African swine fever on two farms in the Netherlands in 1986. Although the ELISA was less sensitive than the immunoperoxidase monolayer assay on sera taken early after infection, the tests were equally useful for screening purposes. The isotype-specific assays gave epizootiological information about the stage of infection on the two farms.     

Isotype-specific antibody responses to bovine coronavirus structural proteins in serum, feces, and mucosal secretions from experimentally challenge-exposed colostrum-deprived calves.

Five newborn isolation-reared colostrum-deprived calves were inoculated orally and intranasally when they were 20 to 30 hours old and challenge exposed when they were 21 days old with a suspension of virulent bovine coronavirus (BCV). Blood, feces, nasal swabs, tears, saliva, and bronchoalveolar lavage (BAL) fluids were collected from each calf prior to inoculation and then weekly for 5 post-inoculation weeks. An ELISA was used to quantitate the immunoglobulin isotype titers of BCV antibodies in all samples. An immunoblot assay was used to determine the antibody isotype responses to BCV structural proteins in all the samples, except saliva. At postinoculation days 2 to 3, all calves had severe watery diarrhea, shed BCV in their feces, and had evidence of BCV replication in their upper respiratory tract. After challenge exposure, no calves became ill and no evidence of BCV replication in the respiratory or intestinal tracts was detected. At postinoculation week 1, IgM responses to the N protein were seen in mucosal secretions (except nasal fluid) and feces. At postinoculation weeks 2 and 3, IgA was predominant in mucosal secretions and feces directed toward all the BCV proteins (except the E2 protein in BAL fluid). After challenge exposure, an increase (or failure to decrease) in most IgA and some IgG1 titers to BCV proteins was seen. The increases in IgA titers were to all viral proteins in all mucosal secretions and feces, except to the N and E1 viral proteins in feces. The IgG1 titer increases were to the E2 proteins in tears and BAL fluid and to the E3 protein in BAL fluid.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isotype-specific antibody responses of cattle to Salmonella Dublin lipopolysaccharide and porin following Salmonella Dublin vaccination and acute and chronic infection.

Stimulation of different T-cell subsets during antigen presentation influences the antibody isotype response to an antigen. Salmonella infection and Salmonella bacterin vaccination are likely to stimulate different T-cell subtypes. The objective of this study was to determine whether there are differences in the isotype response of cattle to Salmonella antigens following Salmonella infection and Salmonella bacterin vaccination. Sera from Salmonella bacterin-vaccinated, experimentally infected, and chronically infected (carrier) adult cattle collected during previous studies was used to evaluate the IgG1, IgG2, and IgM isotype responses of cows to Salmonella serotype Dublin lipopolysaccharide (LPS) and porin. Following vaccination and experimental oral infection, IgG1 titers to LPS and porin rose more quickly and persisted longer than did IgG2 titers. In contrast to Salmonella infection, bacterin vaccination stimulated a weak response to Salmonella porin. Salmonella infection also induced a higher IgG2:IgG1 titer ratio to LPS than did bacterin vaccination. Chronic Salmonella infection induced the highest LPS and porin IgG2:IgG1 titer ratios and the highest correlation between LPS and porin titers. Response operating characteristic curves for each isotype-specific enzyme-linked immunosorbent assay (ELISA) were determined to evaluate the effect of isotype on the sensitivity and specificity of Salmonella ELISA serology for distinguishing sera of Salmonella carriers from those of vaccinated and acutely infected cows. IgG2 titers to LPS and porin provide a more specific indicator of chronic Salmonella infection status than do IgG1 titers to the same antigens with little to no loss in sensitivity.     

Protective immunity following immunisation of pigs with aerosol of Actinobacillus pleuropneumoniae serotype 2

To introduce antigen to the respiratory mucosa, killed Actinobacillus pleuropneumoniae with quil A as adjuvant was administered to pigs as an aerosol. Immunisation by this aerosol induced a marked IgA response in the bronchoalveolar and nasal fluids, and in the serum. Following challenge with live bacteria two weeks after the last exposure to the aerosol, the immunised pigs were protected from the severe pleuropneumonia which developed in non-immunised pigs. The immunised pigs had lower antibody titres in the mucosal fluids and serum after exposure to the challenge. The immune response after experimental infection of non-immunised animals was a weak IgA antibody response in the bronchoalveolar and nasal fluids, whereas the systemic immune response after challenge included both IgA and IgG antibodies.     

牛磺脱氧胆酸钠和CpGDNA对灭活H9N2禽流感病毒鼻腔免疫鸭的呼吸道抗体分泌细胞的影响

运用牛磺脱氧胆酸钠和CpG DNA配合鸭源禽流感H9N2灭活病毒滴鼻免疫雏鸭,通过检测鸭呼吸道各组织中IgA和IgG抗体分泌细胞面积的变化对免疫效果进行评价.结果发现:应用牛磺脱氧胆酸钠和CpG DNA配合H9N2灭活病毒鼻腔免疫后3、5和7周,鼻腔、气管和气管叉组织中的IgA和IgG分泌细胞面积显著或极显著(P＜0.05或P＜0.01)高于单独H9N2灭活病毒免疫后的水平;应用CpG DNA配合H9N2灭活病毒鼻腔免疫后鼻腔和气管组织中IgA和IgG分泌细胞的面积有部分提高(P＜0.05);而单独运用H9N2灭活病毒鼻腔免疫后IgA和IgG分泌细胞面积同对照组相比没有显著差异.结果表明:在牛磺脱氧胆酸钠和CpG DNA的配合下,禽流感H9N2灭活病毒鼻腔免疫能够提高雏鸭呼吸道组织中IgA分泌细胞和IgG分泌细胞的面积,有效地增强呼吸道局部的免疫应答水平.     

Immunoglobulin isotypes in sera and nasal mucosal secretions and their neonatal transfer and distribution in horses

OBJECTIVE: To determine concentrations of IgA and IgG subclasses in serum, colostrum, milk, and nasal wash samples of adult horses and foals. ANIMALS: Seven 2-year-old Welsh ponies, 27 adult mixed-breed horses, and 5 Quarter Horse mares and their foals. PROCEDURE: Serum was obtained from ponies and adult horses. Colostrum and milk were obtained from mares and serum and nasal wash samples from their foals immediately after parturition and on days 1, 7, 14, 28, 42, and 63. Nasal wash samples were also obtained from 23 adult horses. Concentrations of immunoglobulins were determined by use of inhibition ELISA. To determine transfer of maternal isotypes to foals, concentrations in colostrum and milk were compared with those in foal serum. Serum half-lives of isotypes in foals were also determined. RESULTS: IgGb was the most abundant isotype in serum and colostrum from adult horses, whereas IgA was the predominant isotype in milk. The major isotype in nasal secretions of adult horses and foals > or = 28 days old was IgA, but IgGa and IgGb were the major isotypes in nasal secretions of foals < or = 14 days old. Serum half lives of IgGa, IgGb, IgG(T), and IgA in foals were 176, 32, 21, and 3.4 days, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The early immunoglobulin repertoire of neonatal foals comprised IgGa, IgG(T), and IgA; endogenous synthesis of IgGb could not be detected until 63 days after birth. The restricted repertoire of immunoglobulins in foals may influence humoral immune responses to vaccination.     

Comparison of three serological assays to determine the cross-reactivity of antibodies from eight genetically diverse U.S. Swine influenza viruses.

Swine influenza virus is an economically important pathogen to the U.S. swine industry. New influenza subtypes and isolates within subtypes with different genetic and antigenic makeup have recently emerged in U.S. swineherds. As a result of the emergence of these new viruses, diagnosticians' ability to accurately diagnose influenza infection in pigs and develop appropriate vaccine strategies has become increasingly difficult. The current study compares the ability of subtype-specific commercial enzyme-linked immunosorbent assays (ELISA), hemagglutination inhibition (HI), and serum neutralization (SN) assays to detect antibodies elicited by multiple isolates within different subtypes of influenza virus. Pigs were infected with genetically and antigenically different isolates of the 3 major circulating subtypes within populations of swine (H1N1, H1N2, and H3N2). Serum was collected when all pigs within a group collectively reached HI reciprocal titers >or=160 against that group's homologous challenge virus. The antibody cross-reactivity of the sera between isolates was determined using ELISA, HI, and SN assays. In addition, the correlation between the 3 assays was determined. The assays differed in their ability to detect antibodies produced by the viruses used in the study. The results provide important information to diagnostic laboratories, veterinarians, and swine producers on the ability of 3 common serological assays used in identifying infection with influenza in pigs.     

分泌IgA和IgG的浆细胞在家兔鼻腔中的分布特征

分泌IgA和IgG的浆细胞是黏膜免疫系统中两种重要的效应细胞。本研究旨在探究分泌IgA和IgG的浆细胞在家兔鼻腔中的分布特征。以20只健康成年家兔为研究对象，根据硬腭褶皱和牙齿特征，依次将家兔鼻腔分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ 5段，运用组织学、免疫组织化学、图像分析及统计学方法，对分泌IgA和IgG的浆细胞在家兔鼻腔中的分布特征进行了详细的研究。免疫组化结果显示：分泌IgA和IgG的浆细胞在家兔鼻腔每段都有分布，主要弥散分布于鼻黏膜固有层中；其形态呈圆形或卵圆形，核一般位于细胞一侧，胞质丰富呈阳性反应。统计结果显示：分泌IgA和IgG的浆细胞在鼻腔不同段的分布密度由高到低依次是：鼻腔第Ⅳ段、第Ⅴ段、第Ⅲ段、第Ⅱ段、第Ⅰ段。其中分泌IgA的浆细胞在鼻腔Ⅲ、Ⅳ、Ⅴ段的分布密度显著高于鼻腔Ⅰ、Ⅱ段（P<0.05），在上颌鼻甲、鼻中隔和筛鼻甲的分布密度显著高于上鼻甲（P<0.05）；与分泌IgA的浆细胞相比，分泌IgG的浆细胞除鼻腔第Ⅳ段的分布密度显著高于鼻腔Ⅲ、Ⅴ段（P<0.05）外，其分布变化趋势基本与分泌IgA的浆细胞类似。结果证明，分泌IgA和IgG的浆细胞弥散分布于家兔每段鼻腔的鼻黏膜固有层中，有利于SIgA和IgG分子在整个鼻黏膜形成完整的保护屏障；分泌IgA和IgG的浆细胞主要分布在家兔鼻腔Ⅲ、Ⅳ、Ⅴ段及上颌鼻甲、筛鼻甲和鼻中隔，提示这些区域是家兔鼻腔免疫的重要效应部位。本研究为家兔呼吸系统疾病的预防及进一步探讨家兔鼻腔免疫应答的机制提供重要的理论依据。     

The immunogenicity and efficacy of replication-defective and replication-competent bovine adenovirus-3 expressing bovine herpesvirus-1 glycoprotein gD in cattle

Replication-competent and replication-defective bovine adenovirus type 3 recombinants expressing the bovine herpesvirus type 1 (BHV-1) glycoprotein D (gD) were tested for induction of gD specific immune responses in calves using intratracheal (1st and 2nd immunization) and sub-cutaneous (3rd immunization) route of immunization. The replication-defective recombinant BAV501 induced systemic immune responses against gD as low titers of anti gD-IgG were detected in the serum. However, the efficacy of the replication-competent BAV3.E3gD to induce gD-specific antibodies in the serum and the nasal secretions was superior to that of replication-defective BAV501 when both viruses were given at the same dosage. Partial protection from challenge was induced in calves immunized with replication-competent BAV3.E3gD. A dramatic increase in the titers of anti-gD IgG and IgA levels, both in serum and nasal secretions, following BHV-1 challenge (anamnestic response) suggested that the animals immunized with replication-defective BAV501 had been primed for gD-specific antibody responses.     

Safety, efficacy, and immunogenicity of a modified-live equine influenza virus vaccine in ponies after induction of exercise-induced immunosuppression

OBJECTIVE: To determine safety, efficacy, and immunogenicity of an intranasal cold-adapted modified-live equine influenza virus vaccine administered to ponies following induction of exercise-induced immunosuppression. DESIGN: Prospective study. ANIMALS: Fifteen 9- to 15-month old ponies that had not had influenza. PROCEDURE: Five ponies were vaccinated after 5 days of strenuous exercise on a high-speed treadmill, 5 were vaccinated without undergoing exercise, and 5 were not vaccinated or exercised and served as controls. Three months later, all ponies were challenged by nebulization of homologous equine influenza virus. Clinical and hematologic responses and viral shedding were monitored, and serum and nasal secretions were collected for determination of influenza-virus-specific antibody isotype responses. RESULTS: Exercise caused immunosuppression, as indicated by depression of lymphocyte proliferation in response to pokeweed mitogen. Vaccination did not result in adverse clinical effects, and none of the vaccinated ponies developed clinical signs of infection following challenge exposure. In contrast, challenge exposure caused marked clinical signs of respiratory tract disease in 4 control ponies. Vaccinated and control ponies shed virus after challenge exposure. Antibody responses to vaccination were restricted to serum IgGa and IgGb responses in both vaccination groups. After challenge exposure, ponies in all groups generated serum IgGa and IgGb and nasal IgA responses. Patterns of serum hemagglutination inhibition titers were similar to patterns of IgGa and IgGb responses. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that administration of this MLV vaccine to ponies with exercise-induced immunosuppression was safe and that administration of a single dose to ponies provided clinical protection 3 months later.