Primary Antibody Response Research Articles

TRPV1+ Neurons are Required for Antigen‐Specific Immune Responses

The lung is densely innervated by sensory neurons expressing nociceptors including transient receptor potential vanilloid channel 1 (TRPV1+). Nociceptors detect and respond to pathogen-associated molecular patterns and other inflammatory mediators. However, the function of nociceptors in regulating lung antigen-specific immune responses is unknown. Here, using chemogenetic mice we reveal sensory nociceptor fibers expressing TRPV1+ are required for efficient antigen-specific immune responses. Chemogenetics enable temporal control of neuron activity using Designer Receptors Exclusively Activated by Designer Drugs (DREADD). Inhibitory G protein (Gi-DREADD) is a modified muscarinic acetylcholine receptor that binds the ligand, clozapine-N-oxide (CNO), which triggers inhibitory G protein signaling to inhibit neuronal excitability. To selectively silence TRPV1+ nociceptors, we generated TRPV1-Gi-DREADD mice to transiently inhibit neuronal activity specifically in TRPV1+ neurons. CNO or Vehicle was administered intraperitoneally to TRPV1-Gi-DREADD mice 30 minutes prior to intratracheal immunization with 4-Hydroxy-3-nitrophenylacetyl hapten coupled to ovalbumin (NP27-OVA). Chemogenetic inhibition of TRPV1+ neurons, before primary immunization, significantly diminishes NP-specific antibody responses. We observe a significant reduction in NP-specific IgG in mice receiving CNO as compared to vehicle controls at 14 days post-immunization (Anti-NP IgG1 U/mL, Mean ± SEM, D14: vehicle, 120,877 ± 29,519, n=10 versus CNO, 42,525 ± 14,641, n=11, ** p=0.0017). These results indicate TRPV1+ sensory neurons are required to initiate primary antibody responses to novel antigens. These findings offer significant new insights into the biological mechanisms of vaccination.

Antibody Responses in Cats Following Primary and Annual Vaccination against Feline Immunodeficiency Virus (FIV) with an Inactivated Whole-Virus Vaccine (Fel-O-Vax® FIV).

Although the antibody response induced by primary vaccination with Fel-O-Vax® FIV (three doses, 2–4 weeks apart) is well described, the antibody response induced by annual vaccination with Fel-O-Vax® FIV (single dose every 12 months after primary vaccination) and how it compares to the primary antibody response has not been studied. Residual blood samples from a primary FIV vaccination study (n = 11), and blood samples from cats given an annual FIV vaccination (n = 10), were utilized. Samples from all 21 cats were tested with a commercially available PCR assay (FIV RealPCRTM), an anti-p24 microsphere immunoassay (MIA), an anti-FIV transmembrane (TM; gp40) peptide ELISA, and a range of commercially available point-of-care (PoC) FIV antibody kits. PCR testing confirmed all 21 cats to be FIV-uninfected for the duration of this study. Results from MIA and ELISA testing showed that both vaccination regimes induced significant antibody responses against p24 and gp40, and both anti-p24 and anti-gp40 antibodies were variably present 12 months after FIV vaccination. The magnitude of the antibody response against both p24 and gp40 was significantly higher in the primary FIV vaccination group than in the annual FIV vaccination group. The differences in prime versus recall post-vaccinal antibody levels correlated with FIV PoC kit performance. Two FIV PoC kits that detect antibodies against gp40, namely Witness® and Anigen Rapid®, showed 100% specificity in cats recently administered an annual FIV vaccination, demonstrating that they can be used to accurately distinguish vaccination and infection in annually vaccinated cats. A third FIV PoC kit, SNAP® Combo, had 0% specificity in annually FIV-vaccinated cats, and should not be used in any cat with a possible history of FIV vaccination. This study outlines the antibody response to inactivated Fel-O-Vax® FIV whole-virus vaccine, and demonstrates how best to diagnose FIV infection in jurisdictions where FIV vaccination is practiced.

AMPKα1 in B Cells Dampens Primary Antibody Responses yet Promotes Mitochondrial Homeostasis and Persistence of B Cell Memory.

Emerging evidence indicates that metabolic programs regulate B cell activation and Ab responses. However, the metabolic mediators that support the durability of the memory B cell and long-lived plasma cell populations are not fully elucidated. Adenosine monophosphate-activated protein kinase (AMPK) is an evolutionary conserved serine/threonine kinase that integrates cellular energy status and nutrient availability to intracellular signaling and metabolic pathways. In this study, we use genetic mouse models to show that loss of ΑMPKα1 in B cells led to a weakened recall Ab response associated with a decline in the population of memory-phenotype B cells. AMPKα1-deficient memory B lymphocytes exhibited aberrant mitochondrial activity, decreased mitophagy, and increased lipid peroxidation. Moreover, loss of AMPKα1 in B lymphoblasts was associated with decreased mitochondrial spare respiratory capacity. Of note, AMPKα1 in B cells was dispensable for stability of the bone marrow-resident, long-lived plasma cell population, yet absence of this kinase led to increased rates of Ig production and elevated serum Ab concentrations elicited by primary immunization. Collectively, our findings fit a model in which AMPKα1 in B cells supports recall function of the memory B cell compartment by promoting mitochondrial homeostasis and longevity but restrains rates of Ig production.

Infant antibody levels following 10-valent pneumococcal-protein D conjugate and DTaP-Hib vaccinations in the first year of life after maternal Tdap vaccination: An open-label, parallel, randomised controlled trial

BackgroundMaternal antibody levels after Tdap vaccination during pregnancy may affect infant primary antibody responses to pertussis, Tetanus toxoid (TT), Diphtheria toxoid (DT) vaccinations and pneumococcal vaccines with diphtheria toxin mutants like CRM197 as carrier protein. MethodsMothers were recruited in an open label randomised parallel controlled trial in 2014–2016 through midwifes. They received Tdap [Boostrix] at 30–32 weeks of pregnancy (n = 58) or within 48 h after delivery (n = 60). Infants received DTaP-IPV-Hib-HepB [Infanrix Hexa] and 10-valent protein D conjugated pneumococcal conjugate vaccine (PHiD-CV10 [Synflorix]) at age 3, 5 and 11 months. We now report on infant specific IgG levels towards DT, TT, Haemophilus influenzae type b polyribosylribitol phosphate (Hib PRP) and PHiD-CV10 before and after primary- and booster vaccination as secondary study endpoints; pertussis antibodies were the primary endpoint of the study. This trial is registered in clinicaltrialsregister.eu (EudraCT 2012–004006-9) and trialregister.nl (NTR number NTR4314). FindingsPost primary vaccinations, antibody levels to DT, but not TT, were significantly lower after Tdap vaccination during pregnancy compared to controls (GMC ratio 0.4, 95% CI 0.3–0.6 and 0.9, 95% CI 0.6–1.2, respectively). Antibodies to serotype 19F were significantly lower in the maternal Tdap group, whereas there were no differences in antibody levels to Hib PRP and the other 9 pneumococcal serotypes. Post booster vaccinations, no significant differences were observed, except for DT. InterpretationMaternal Tdap vaccination results in significant interference with infants responses not only to DT but also to conjugated pneumococcal vaccines containing DT mutants as carrier proteins. These interactions after maternal Tdap vaccination need to be taken into account when designing infants’ national immunization schedules and choice of vaccines. FundingThe Dutch Ministry of Health, Welfare and Sport.

Evaluation of infection with N protein-specific Immunoglobulin M and G in naturally occurring distemper in dogs

In dogs, canine distemper has a worldwide distribution with high morbidity/mortality, despite the widespread usage of vaccines and has no specific treatment. In susceptible animals with the canine distemper virus, respiratory, gastrointestinal and nervous system disorders, immunosuppression and cutaneous lesions can also be seen. Especially puppies and unvaccinated dogs are prone to get the viral infection. IgM and IgG antibodies constitute the major component of the natural antibodies produced during the primary and secondary antibody response that have long been recognised to inhibit viral infections. In the present study, the presence of the viral N protein-specific IgM and IgG was investigated by indirect ELISA in naturally infected dogs. Moreover, the rate of outbreaks in naturally infected dogs was shown by the detection of new and re-infections. In the Western Mediterranean region, blood serum samples were collected from 50 unvaccinated dogs for the mentioned infection between 2015 and 2017. At 0–12 months, in the dogs with clinical symptoms, the indirect ELISA detected 4% acute, 54% early convalescent, 40% late convalescent and 2% no infections phases. The clinical manifestations were studied in four main groups follow as: respiratory, gastrointestinal, nervous and cutaneous symptoms. The evaluation showed that the canine distemper virus N protein-specific antibodies detection by the indirect ELISA is quick and safe in naturally infected dogs. In conclusion, the method is very useful for the pre-diagnosis of the disease when evaluated together with the clinical symptoms. It helps to distinguish acute and convalescent (early/late) phases. Distinguishing these phases of infection is important for monitoring the spread of the outbreaks and identifying the risk of severe forms of canine distemper.

Influenza-infected newborn and adult monkeys exhibit a strong primary antibody response to hemagglutinin stem.

The specificity of antibodies (Abs) generated against influenza A virus (IAV) infection can significantly alter protection and viral clearance. At present, the impact of age upon this process is relatively unexplored. Here, we evaluated the Ab response in newborn and adult African green monkeys following infection with IAV using a strain that enables us to determine the immunodominance (ID) hierarchy of the Ab response to hemagglutinin (HA), the principal target of protective Abs. This revealed altered ID patterns in the early IgM anti-HA response in newborns versus adults that converged over time. While the IgG ID profiles for HA in newborn and adult monkeys were similar, this was not the case for IgA. Importantly, HA stem-specific Abs were generated robustly and similarly in newborns and adults in terms of quality and quantity. Together, these results demonstrate that newborns and adults can differ in the Ab ID pattern established following infection and that the ID pattern can vary across isotypes. In addition, newborns have the ability to generate potent HA stem-specific Ab responses. Our findings further the understanding of the newborn response to IAV antigens and inform the development of improved vaccines for this at-risk population.

Intestinal microbial ecology, immune response, stress indicators, and gut morphology of male broiler chickens fed low-phosphorus diets supplemented with phytase, butyric acid, or Saccharomyces boulardii

Six dietary treatments were applied in a 42-d study to determine the effect of phytase, butyric acid, and S. boulardii on productive performance, intestinal microflora, immune response, stress indicators, and gut morphology in broiler chickens fed diets with reduced content of nonphytate P (nPP). On d 0, a total of 750 male broiler chickens were randomly allotted to 6 treatments with 5 pens of 25 broiler chickens for each diet: positive control (PC, adequate amounts of nPP), negative control (NC, 0.1% reduction in dietary nPP content), NC + 500 FTU phytase/kg (PHY), NC + 2 g butyric acid/kg (BA), NC + 1 × 108 cfu S. boulardii /kg (SB), and NC + butyric acid + S. boulardii (BA + SB). Considering the entire study period, body weight gain in broiler chickens fed any of the diets were greater (P < 0.05) than in broiler chickens fed the NC diet, where the broiler chickens fed diets PHY and BA + SB had the greatest value. Broiler chickens fed diets PC, PHY, SB, and BA + SB had greater (P < 0.05) relative thymus weight, primary and secondary antibody response against infectious bronchitis virus vaccine, and cutaneous basophil hypersensitivity to phytohaemagglutinin-P, but lower (P < 0.05) mortality rate and blood corticosterone concentration than those fed the NC diet at d 42. Feeding diet BA + SB increased (P < 0.05) cecal Lactobacillus spp. counts (d 35) and jejunal villus high:crypt depth (d 42), but decreased (P < 0.05) cecal Clostridium spp. counts (d 35) compared with those fed the NC diet. On d 35, the PHY, BA, SB, and BA + SB treatments had also the lower (P < 0.05) population of E. coli and Clostridium spp. in the ileum. No diets affected feed intake, relative weights of abdominal fat and liver, the population of total anaerobic bacteria, Bifidobacterium spp., and Coliforms in both ileum and ceca, serum insulin concentration, and duodenal morphology. In conclusion, the combination of butyric acid and S. boulardii may have synergistic effects on improving productive performance, immune response, intestinal microflora, and gut morphology in broiler chickens fed the low-nPP diet.

Impact of flavivirus vaccine-induced immunity on primary Zika virus antibody response in humans.

BackgroundZika virus has recently spread to South- and Central America, causing congenital birth defects and neurological complications. Many people at risk are flavivirus pre-immune due to prior infections with other flaviviruses (e.g. dengue virus) or flavivirus vaccinations. Since pre-existing cross-reactive immunity can potentially modulate antibody responses to Zika virus infection and may affect the outcome of disease, we analyzed fine-specificity as well as virus-neutralizing and infection-enhancing activities of antibodies induced by a primary Zika virus infection in flavivirus-naïve as well as yellow fever- and/or tick-borne encephalitis-vaccinated individuals.MethodologyAntibodies in sera from convalescent Zika patients with and without vaccine-induced immunity were assessed by ELISA with respect to Zika virus-specificity and flavivirus cross-reactivity. Functional analyses included virus neutralization and infection-enhancement. The contribution of IgM and cross-reactive antibodies to these properties was determined by depletion experiments.Principal findingsPre-existing flavivirus immunity had a strong influence on the antibody response in primary Zika virus infections, resulting in higher titers of broadly flavivirus cross-reactive antibodies and slightly lower levels of Zika virus-specific IgM. Antibody-dependent enhancement (ADE) of Zika virus was mediated by sub-neutralizing concentrations of specific IgG but not by cross-reactive antibodies. This effect was potently counteracted by the presence of neutralizing IgM. Broadly cross-reactive antibodies were able to both neutralize and enhance infection of dengue virus but not Zika virus, indicating a different exposure of conserved sequence elements in the two viruses.ConclusionsOur data point to an important role of flavivirus-specific IgM during the transient early stages of infection, by contributing substantially to neutralization and by counteracting ADE. In addition, our results highlight structural differences between strains of Zika and dengue viruses that are used for analyzing infection-enhancement by cross-reactive antibodies. These findings underscore the possible impact of specific antibody patterns on flavivirus disease and vaccination efficacy.

Early and later life environmental enrichment affect specific antibody responses and blood leukocyte subpopulations in pigs

This study addressed the impact of early and later life environmental enrichment, and their combination, on specific antibody responses and peripheral blood leukocyte subpopulations in pigs. Pigs were kept in either barren (B1) or enriched (E1) housing from birth, and half of the pigs switched to barren or enriched housing on day 47, resulting in four treatment combinations: B1B2, B1E2, E1B2, E1E2). Pigs were immunized with keyhole limpet hemocyanin-conjugated trinitrophenyl (KLH-TNP) on day 74 and 109 to induce primary and secondary antibody responses. Blood samples were taken weekly until day 130, and IgM and IgG antibody responses were measured. Leukocyte subpopulations were measured on day 74 and 130. Time course of the antibody responses was not affected by housing. Early life enrichment increased the IgG response to KLH, particularly the primary one. At day 74 the relative frequency of lymphocytes, DC and SLA-II expression on monocytes were higher in E1 pigs, whereas the percentage of granulocytes tended to be lower in E1 pigs at day 74. Early life enrichment increased the SLA-II expression on monocytes, the granulocyte to lymphocyte ratio, and tended to increase the percentage of granulocytes, but tended to decrease the percentage of monocytes at day 130. Later life enrichment reduced percentages of CD4+CD8α+ T cells before and after immunization and the SLA-II expression on monocytes at day 74, the percentage of granulocytes and the granulocyte to lymphocyte ratio at day 130. Notably, early and later life housing interacted in their effects on several immune parameters. KLH-IgM responses (both primary and secondary) were affected by the interaction between early and later life housing. IgM titers were higher for B1B2 than for E1E2, with the switched animals (B1E2 and E1B2) moving towards the titers of the animals kept in their later life environment from birth onwards. At day 130 the percentage of gamma delta T cells, CD8α+ cytotoxic T cells and DC were not different between pigs kept in B1B2 and E1E2, but there was a clear impact of the switch in housing conditions, particularly for the pigs that changed from barren to enriched housing. We also found effects of coping style (personality) and sex on some immune parameters. In conclusion, both early life and later life enrichment, and, notably a switch in housing conditions influenced specific antibodies and leukocyte subpopulations in pigs. The current study implies that the early life history of animals and the (mis)match with their current environment could thus be of major importance for their immune system. Further research is needed to investigate potential consequences for the pigs’ health.

Typhim vi immunization assists to discriminate primary antibody responses in hematological malignancies

Assessment of specific antibody (Ab)production to polysaccharide antigens is clinically relevant, identifying patients at risk for infection by encapsulated bacteria and thus enabling a more rigorous selection of patients that can benefit of immunoglobulin replacement therapy. Classically, the gold-standard test is the measurement of antibody production to pure polysaccharide pneumococcal (PPV)immunization. Several factors, including introduction of conjugate vaccination schedule, serotyping analysis, high baseline Ablevels, have hinderedthe evaluation of polysaccharide antigens. This is even more difficult in secondary immunodeficiencies (SID), where patients can show secondary responses despite lack of primary antibody responses and present withrecurrent or severe infections. Assessmentof specific Ab production to pure Salmonella typhi Vipolysaccharide(TV) immunizationhasbeen proposed as a complementary test to PPV, given its low seroprevalence.Toset theoptimalcut-offvalue for PPVand TVresponse in SID,we tested different biostatistical methodologies, including ROC analysis, Youden index, Union index and Closest-topleft in a cohort of 42 SID patients and 24 healthycontrols. The statistically chosen cut-offs valuepre-post TVAbratio was≥5, (sensitivity of 90%,specificity of 100%) and a postvaccination TV concentration of 28.5 U/mL (sensitivity of 90%, specificity of 95%), showing relevant clinical correlate.

ZBTB32 restrains antibody responses to murine cytomegalovirus infections, but not other repetitive challenges

ZBTB32 is a transcription factor that is highly expressed by a subset of memory B cells and restrains the magnitude and duration of recall responses against hapten-protein conjugates. To define physiological contexts in which ZBTB32 acts, we assessed responses by Zbtb32−/− mice or bone marrow chimeras against a panel of chronic and acute challenges. Mixed bone marrow chimeras were established in which all B cells were derived from either Zbtb32−/− mice or control littermates. Chronic infection of Zbtb32−/− chimeras with murine cytomegalovirus led to nearly 20-fold higher antigen-specific IgG2b levels relative to controls by week 9 post-infection, despite similar viral loads. In contrast, IgA responses and specificities in the intestine, where memory B cells are repeatedly stimulated by commensal bacteria, were similar between Zbtb32−/− mice and control littermates. Finally, an infection and heterologous booster vaccination model revealed no role for ZBTB32 in restraining primary or recall antibody responses against influenza viruses. Thus, ZBTB32 does not limit recall responses to a number of physiological acute challenges, but does restrict antibody levels during chronic viral infections that periodically engage memory B cells. This restriction might selectively prevent recall responses against chronic infections from progressively overwhelming other antibody specificities.

Neonatal T Follicular Helper Cells Are Lodged in a Pre-T Follicular Helper Stage Favoring Innate Over Adaptive Germinal Center Responses.

T follicular helper (Tfh) cells have emerged as a critical limiting factor for controlling the magnitude of neonatal germinal center (GC) reactions and primary vaccine antibody responses. We compared the functional attributes of neonatal and adult Tfh cells at the transcriptomic level and demonstrated that the Tfh cell program is well-initiated in neonates although the Tfh gene-expression pattern (i.e., CXCR5, IL-21, BCL6, TBK1, STAT4, ASCL2, and c-MAF) is largely underrepresented as compared to adult Tfh cells. Importantly, we identified a TH2-bias of neonatal Tfh cells, with preferential differentiation toward short-lived pre-Tfh effector cells. Remarkably, adjuvantation with CpG-ODNs redirect neonatal pre-Tfh cells toward committed GC-Tfh cells, as illustrated by increased expression of Tfh signature genes and reduced expression of TH2-related genes.

Bridging Vaccine-Induced HIV-1 Neutralizing and Effector Antibody Responses in Rabbit and Rhesus Macaque Animal Models.

Studies in animal models are essential prerequisites for clinical trials of candidate HIV vaccines. Small animals, such as rabbits, are used to evaluate promising strategies prior to further immunogenicity and efficacy testing in nonhuman primates. Our goal was to determine how HIV-specific vaccine-elicited antibody responses, epitope specificity, and Fc-mediated functions in the rabbit model can predict those in the rhesus macaque (RM) model. Detailed comparisons of the HIV-1-specific IgG response were performed on serum from rabbits and RM given identical modified vaccinia virus Ankara-prime/gp120-boost immunization regimens. We found that vaccine-induced neutralizing antibody, gp120-binding antibody levels and immunodominant specificities, antibody-dependent cellular phagocytosis of HIV-1 virions, and antibody-dependent cellular cytotoxicity (ADCC) responses against gp120-coated target cells were similar in rabbits and RM. However, we also identified characteristics of humoral immunity that differed across species. ADCC against HIV-infected target cells was elicited in rabbits but not in RM, and we observed differences among subdominantly targeted epitopes. Human Fc receptor binding assays and analysis of antibody-cell interactions indicated that rabbit vaccine-induced antibodies effectively recruited and activated human natural killer cells, while vaccine-elicited RM antibodies were unable to activate either human or RM NK cells. Thus, our data demonstrate that both Fc-independent and Fc-dependent functions of rabbit antibodies can be measured with commonly used in vitro assays; however, the ability of immunogenicity studies performed in rabbits to predict responses in RM will vary depending on the particular immune parameter of interest.IMPORTANCE Nonneutralizing antibody functions have been associated with reduced infection risk, or control of virus replication, for HIV-1 and related viruses. It is therefore critical to evaluate development of these responses throughout all stages of preclinical testing. Rabbits are conventionally used to evaluate the ability of vaccine candidates to safely elicit antibodies that bind and neutralize HIV-1. However, it remained unexplored how effectively rabbits model the development of nonneutralizing antibody responses in primates. We administered identical HIV-1 vaccine regimens to rabbits and rhesus macaques and performed detailed comparisons of vaccine-induced antibody responses. We demonstrated that nonneutralizing HIV-specific antibody responses can be studied in the rabbit model and have identified aspects of these responses that are common, and those that are unique, to rabbits and rhesus macaques. Our findings will help determine how to best utilize preclinical rabbit and rhesus macaque models to accelerate HIV vaccine candidate testing in human trials.

Natural gene-encoded affinity for cognate antigen facilitates vaccine-amplification of broadly neutralizing antibodies against influenza virus

Abstract B cell receptors display V gene-encoded CDRs and hypervariable CDR3, where the former may harbor innate-like antigen recognition characteristics. To test this in vivo, we deployed transgenic mice containing full human CDRH3 diversity but were constrained to single human VH genes: IGHV1-69*01, a human VH reproducibly used to generate broadly neutralizing antibodies (bnAbs) targeting hemagglutinin stalk of Group 1 influenza A viruses or irrelevant IGHV1-2*02. With this system, we could experimentally evaluate the contribution of V gene encoded CDRs to forming the antibody paratope following immune challenge. Exposure to virus or hemagglutinin vaccine-nanoparticles elicited primary antibody responses targeting the bnAb epitope, but only in IGHV1-69 animals. Repeated exposure amplified off-target responses, however, prime/boost with stalk-only nanoparticle (SS-np) refocused serum antibodies to the target-epitope, expanding the human IGHV1-69 bnAb lineage to elicit prototypic IGHV1-69 Group 1 bnAbs. The bnAb pathway was expanded from a genetically endowed but low frequency population of on target germline B cell precursors (&amp;lt;0.3% of the repertoire). IGHV1-69 therefore endows natural cognate anti-influenza targeting affinity which can be exploited through rational vaccine design to redirect antibodies against an otherwise immunologically silent ‘universal’ flu vaccine target. Remarkably, similar on-target germline B cell levels were seen in human PBMC, suggesting SS-np may elicit bnAbs in humans.

The effects of dietary vitamin C and Citrus Sinensis peel on growth, hematological characteristics, immune competence, and carcass characteristics in broilers exposed to heat stress

This study investigated the role of vitamin C and Citrus Sinensis peel (sweet orange peel (Sop)) on growth, carcass characteristics and health status in 160 one day old broiler chickens (Ross308) which were randomly divided into four equal groups consisting 4 pens. Each pen having 10 birds (5 male and 5 female) for 35 days. All chicks were exposed to heat stress (330C) during all the experimental period (35 days). Group one considered as control, groups 2, 3, 4 were given feed containing vitamin C (500ppm/ feed), sweet orange peel (Sop) (1,2 % respectively). Sop 2% significantly increased average body weight gain and feed intake during the grower period (16-28) (P<0.05). The birds fed Sop 2% during the whole experimental period had higher FI and greater feed conversion ratio (P<0.05) compared to the other groups. The mortality rate tended to be the lowest in the birds fed the feed additives (P<0.05). The relative weight of internal organs, blood profiles pictures were not affected by Sop with two tested levels (P<0.05) or vitamin C compared with the control group. Broiler fed vitamin C or Sop levels had greater primary and secondary antibody responses to sheep red blood cells (SRBC) and against phytohemagglutinin (PHA-P) antigen compared with those in the control group (P<0.05). Sop and vitamin C increased antibodies titer against Newcastle disease during the secondary antibody response (P<0.05). Overall, Sop as feed additive improved immune responses in broiler chickens under heat stress. Also the result indicate that the Sop 2 % during the grower period had a positive effect on growth performance of broiler chickens under heat stress.

Suppressive effects of IgA on IgE-enhanced primary antibody response

Suppressive effects of IgA on IgE-enhanced primary antibody response

IL-9 receptor signaling in memory B cells regulates humoral recall responses.

Memory B cells (Bmem cells) are the basis of long-lasting humoral immunity. They respond to re-encountered antigens by rapidly producing specific antibodies and forming germinal centers (GCs), a recall response that has been known for decades but remains poorly understood. We found that the receptor for the cytokine IL-9 (IL-9R) was induced selectively on Bmem cells after primary immunization and that IL-9R-deficient mice exhibited a normal primary antibody response but impaired recall antibody responses, with attenuated population expansion and plasma-cell differentiation of Bmem cells. In contrast, there was augmented GC formation, possibly due to defective downregulation of the ligand for the co-stimulatory receptor ICOS on Bmem cells. A fraction of Bmem cells produced IL-9. These findings indicate that IL-9R signaling in Bmem cells regulates humoral recall responses.

Rapid immune reconstitution of SCID-X1 canines after G-CSF/AMD3100 mobilization and in vivo gene therapy

AbstractHematopoietic stem-cell gene therapy is a promising treatment of X-linked severe combined immunodeficiency disease (SCID-X1), but currently, it requires recipient conditioning, extensive cell manipulation, and sophisticated facilities. With these limitations in mind, we explored a simpler therapeutic approach to SCID-X1 treatment by direct IV administration of foamy virus (FV) vectors in the canine model. FV vectors were used because they have a favorable integration site profile and are resistant to serum inactivation. Here, we show improved efficacy of our in vivo gene therapy platform by mobilization with granulocyte colony-stimulating factor (G-CSF) and AMD3100 before injection of an optimized FV vector incorporating the human phosphoglycerate kinase enhancerless promoter. G-CSF/AMD3100 mobilization before FV vector delivery accelerated kinetics of CD3+ lymphocyte recovery, promoted thymopoiesis, and increased immune clonal diversity. Gene-corrected T lymphocytes exhibited a normal CD4:CD8 ratio and a broad T-cell receptor repertoire and showed restored γC-dependent signaling function. Treated animals showed normal primary and secondary antibody responses to bacteriophage immunization and evidence for immunoglobulin class switching. These results demonstrate safety and efficacy of an accessible, portable, and translatable platform with no conditioning regimen for the treatment of SCID-X1 and other genetic diseases.

Induction of class-switched and somatically hypermutated primary and anamnestic antibody responses by TLR-BCR co-engagement in Tcrβ −/− Tcrδ −/−and NSG/B-cell mice

Abstract Ig gene CSR/SHM as well as plasma cell and memory B cell differentiation are central processes to the maturation of the antibody response and generally depend on T cell help. Prompted by our findings that CSR is efficiently induced by T cell-independent (TI) stimuli in vitro, e.g., dual engagement of TLR/BCR, here we have addressed the induction of TI antibody responses and underlying mechanisms in vivo using Tcrβ−/−Tcrδ−/− mice. These mice lack T cells and, as expected, failed to generate any class-switched antibodies to T-dependent antigens (e.g., NP-CGG and ovalbumin), even in the presence of adjuvants. They, however, displayed circulating IgG2b, IgG3 and IgA, at levels comparable to those in C57BL/6 mice, and to a lesser extent, IgG1 and IgG2a. Further, they generated high-affinity NP-specific IgG2b and IgG3 upon immunization with NP-LPS, but not NP-Ficoll mixed with LPS. The anti-NP-LPS response entailed a high-frequency of (replacement) mutations in the Ig variable region, a hallmark of antibody affinity maturation, CSR and generation of a high number of NP-binding IgG+B cells. Also generated at a high frequency were IgG+NP-specific plasma cells, which homed to the bone marrow, and memory B cells, which were instrumental in mounting an effective anamnestic response. These findings, together with the readily detectable NP-specific response to NP-LPS in immune-deficient NSG mice grafted with highly purified B cells, highlight a previously unsuspected but efficient TI and B cell-intrinsic mechanism, i.e., TLR/BCR co-engagement, in the generation of full-fledged antibody responses. The B cell-intrinsic nature of this mechanism was further emphasized by the failure of mice with B cell-specific Tlr4 deficiency to respond to NP-LPS.

Memory control by the B cell antigen receptor.

The generation of memory B cells (MBCs) that have undergone immunoglobulin class switching from IgM, which dominates primary antibody responses, to other immunoglobulin isoforms is a hallmark of immune memory. Hence, humoral immunological memory is characterized by the presence of serum immunoglobulins of IgG subtypes known as the γ-globulin fraction of blood plasma proteins. These antibodies reflect the antigen experience of B lymphocytes and their repeated triggering. In fact, efficient protection against a previously encountered pathogen is critically linked to the production of pathogen-specific IgG molecules even in those cases where the primary immune response required cellular immunity, for example, T cell-mediated clearance of intracellular pathogens such as viruses. Besides IgG, also IgA and IgE can provide humoral immunity depending on the microbe's nature and infection route. The molecular mechanisms underlying the preponderance of switched immunoglobulin isotypes during memory antibody responses are a matter of active and controversial debate. Here, we summarize the phenotypic characteristics of distinct MBC subpopulations and discuss the decisive roles of different B cell antigen receptor isotypes for the functional traits of class-switched B cell populations.