Serum Ab Research Articles

Evaluation of the immune response in conventionally weaned pigs infected with porcine deltacoronavirus.

Although porcine deltacoronavirus (PDCoV) is a significant pandemic threat in the swine population and has caused significant economic losses, information regarding the immune response in conventionally weaned pigs infected with PDCoV is scarce. Hence, the immune response in conventionally weaned pigs infected with PDCoV was assessed after challenge and rechallenge. After the first challenge, obvious diarrhea and viral shedding developed successively in all pigs in the four inoculation dose groups from 3 to 14 days postinfection (dpi), and all pigs recovered (no clinical symptoms or viral shedding) by 21 dpi. All pigs in the four groups exhibited significantly increased PDCoV-specific IgG, IgA and virus-neutralizing (VN) antibody (Ab) titers and IFN-γ levels in the serum after the first challenge. All pigs were completely protected against rechallenge at 21 dpi. The serum levels of PDCoV-specific IgG, IgA, and VN Abs increased further after rechallenge. Notably, the IFN-γ level declined continuously after 7 dpi. In addition, the levels of PDCoV-specific IgG, IgA and VN Abs in saliva increased significantly after rechallenge and correlated well with the serum Ab titers. Furthermore, the appearance of clinical symptoms of PDCoV infection in conventionally weaned pigs was delayed with reduced inoculation doses. In summary, the data presented here offer important reference information for future PDCoV animal infection and vaccine-induced immunoprotection experiments.

CD4+ T cells are dispensable for induction of heterologous tier 2 HIV neutralizing antibodies in rhesus macaques

Abstract Induction of a sustained and broad neutralizing antibody (Ab) response is a major goal in developing a protective HIV vaccine. Many HIV Envelope (Env)-specific broadly neutralizing antibodies isolated to date exhibit substantial somatic hypermutation, and their development in HIV infected individuals has been correlated with T follicular helper responses. This has bolstered the rational that a robust CD4+ T helper cell response will likely be required for the induction of such HIV broadly neutralizing antibody responses by vaccination. Using the VC10014 DNA-protein co-immunization vaccine platform consisting of gp160 envelope plasmids and gp140 trimeric envelope proteins derived from a clade B HIV-1 infected subject who developed broadly neutralizing serum Abs, and which has been previously shown to induce Tier 2 heterologous neutralizing Abs in rabbits and rhesus macaques, we determined the influence of CD4+ T cell depletion during the vaccination regimen on the characteristics of the Env-specific humoral response in rhesus macaques. Both CD4+ depleted and non-depleted animals developed Tier 2 heterologous neutralizing plasma antibodies, with no inferiority in titers among the CD4+ T cell depleted animals. Similarly, there was no diminishment of titers of HIV Env-specific cross-clade binding antibodies, antibody dependent cellular phagocytosis or antibody dependent complement deposition in the CD4+ depleted animals. These results suggest that HIV neutralizing antibodies can be induced in the absence of robust CD4+ T cell help, which may have implications for developing effective HIV vaccine strategies.

Abstract B38: Immunologic monitoring markers of clinical responses to anti-PD-1 therapy for non-small cell lung cancer

Abstract Background: Programmed cell death-1 (PD-1) and PD-ligand1 (PD-L1) inhibitors effectively treat advanced non-small cell lung cancer (NSCLC) and prolong patient survival, resulting in standard therapies of NSCLC. Clinical benefits of good response and long survival with anti-PD-1/L1 therapy are limited in a small population of NSCLC patients, although combinations with chemotherapy have been extensively developed. Tumor PD-L1 expression and mutation burden are well known as response biomarkers for these therapies. On the other hand, biomarkers monitoring clinical responses during anti-PD-1/L1 therapy have yet to be identified. Very recently, we reported robust biomarkers of NY-ESO-1 and XAGE1 serum antibodies (Abs) predicting clinical benefits with anti-PD-1 monotherapy for NSCLC. NY-ESO-1 and XAGE1 are major cancer-testis antigens in NSCLC and play important roles in the immune surveillance. Then, we investigated whether these Abs became monitoring markers of clinical responses to anti-PD-1 monotherapy in NSCLC. Patients and Methods: Patient sera were serially obtained during anti-PD-1 therapy (nivolumab or pembrolizumab) of the first or later line as a standard care, and serum Abs against NY-ESO-1 and XAGE1 antigens and mutant p53 (as neoantigen) were detected by ELISA. Ab-positive was defined for serum with extrapolated titers exceeding or equal to 100 (≥100). Objective responses to anti-PD-1 therapy were assessed according to the Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1. Results: In patients responding to anti-PD-1 therapy, NY-ESO-1/XAGE1 serum Ab titers were increased with several spikes within two to three months after therapy and were gradually decreased with tumor shrinkage. The increase of Ab titers showed rapid or gradual type, and the former reflected rapid tumor shrinkage and the latter did slow one. The Ab titers in patients with complete response (CR) were gradually decreased to an undetectable level, and these patients experienced no recurrence. However, the decreased titers in patients with partial response (PR) remained plateau or under 100, and some of these patients experienced recurrence or regrowth. The Ab titers in patients with progressive disease (PD) were gradually increased and not decreased. On the other hand, p53 serum Ab titers were gradually increased after the peaks of NY-ESO-1/XAGE1 serum Ab titers, suggesting antigen-spreading of neoantigens associated with tumor destruction. Conclusions: Our results suggest that NY-ESO-1 and/or XAGE1 serum Abs are robust monitoring biomarkers of clinical responses to immune checkpoint inhibitors and are useful for decision making regarding the continuation or discontinuation of therapy in clinical settings. Citation Format: Mikio Oka, Koji Kurose, Yoshihiro Ohue, Takahiro Karasaki, Junichiro Futami, Takeshi Masuda, Masaaki Fukuda, Akitoshi Kinoshita, Katsuhiko Shimizu, Masao Nakata, Noboru Hattori, Hiroyuki Yamaguchi, Minoru Fukuda, Toru Oga, Kazuhiro Kakimi. Immunologic monitoring markers of clinical responses to anti-PD-1 therapy for non-small cell lung cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr B38.

Role of Serum and Urine Biomarkers (PLA2R and THSD7A) in Diagnosis, Monitoring and Prognostication of Primary Membranous Glomerulonephritis.

Differentiating primary and secondary membranous glomerulonephritis (MGN) using biomarkers for MGN is essential in patients’ diagnosis, treatment and follow-up. Although biopsy has been the primary tool in making the diagnosis, not all patients can withstand it due to its invasive nature, and it cannot be used to monitor treatment. Hence, there is the need for less invasive or even non-invasive biomarkers for effective diagnosis, treatment monitoring and prognostication. This study aimed at providing an alternative way of differentiating primary and secondary MGN using enzyme-linked immunosorbent assay (ELISA) technique for serum and urine biomarkers (M-type phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A)) for prompt diagnosis, treatment and prognosis. A total of 125 subjects, including 81 primary and 44 secondary MGN subjects, were diagnosed from January 2012 to October 2019 at Hospital Serdang and Hospital Kuala Lumpur from which 69 subjects consisting of 47 primary and 22 secondary MGN subjects participated in the study. Of these, 13 primary MGN subjects were positive for both serum and urine anti-PLA2R antibodies (Ab) whereas only one secondary MGN subject associated with hepatitis B virus was positive for both serum and urine anti-PLA2R Ab. At the same time, anti-THSD7A Ab was found positive in four primary MGN subjects and two secondary MGN subjects with malignancy.

High Levels of Anti-GM-CSF Antibodies in Deep Infiltrating Endometriosis.

Endometriosis is a chronic hormono-dependent inflammatory gynecological disease. Endometriosis can be subdivided into three forms: superficial peritoneal implants, endometrioma, and deep infiltrating endometriosis (DIE). Inflammation is a typical feature of endometriosis with overproduction of prostaglandins, chemokines, and cytokines, like granulocyte-macrophage colony-stimulating factor (GM-CSF). GM-CSF is a hematopoietic growth factor and immune modulator which belongs to the group of cytokines that actively participate in inflammatory reactions. GM-CSF autoantibodies (Ab) are described in inflammatory diseases such as Crohn disease and ulcerative colitis where high concentrations of anti-GM-CSF Ab are correlated with severity, complications, and relapses. We have evaluated the presence of anti-GM-CSF Ab in the serum of 106 patients with endometriosis and 92 controls using a home-made enzyme-linked immunosorbent assay (ELISA) and correlated the results with the form and severity of the disease. We found that anti-GM-CSF Ab level is significantly increased in the sera of patients with endometriosis compared to controls and is associated with the severity of the disease especially in patients with deep endometriosis (p < 0.0001) with the highest number of lesions (p = 0.0034), including digestive involvement (p = 0.0041). We also found a correlation between these levels of anti-GM-CSF Ab and the number of lesions in DIE patients (r = 0.913). In this way, searching anti-GM-CSF Ab in endometriosis patient sera could be of value for patient follow-up and put further insight into the role of inflammation and of GM-CSF in endometriosis pathogenesis.

Development of Monoclonal Antibody Specific to Foot-and-Mouth Disease Virus Type A for Serodiagnosis.

Foot-and-mouth disease (FMD) is a highly contagious and economically devastating disease affecting cloven-hoofed livestock worldwide. FMD virus (FMDV) type A is one of the most common causes of FMD outbreaks among the seven FMDV serotypes, and its serological diagnosis is therefore important to confirm FMDV type A infection and to determine FMD vaccine efficacy. Here, we generated monoclonal antibodies (mAbs) specific to FMDV type A via hybridoma systems using an inactivated FMDV type A (A22/Iraq/1964) and found 4 monoclones (#29, #106, #108, and #109) with high binding reactivity to FMDV type A among 594 primary clones. In particular, the #106 mAb had a higher binding reactivity to the inactivated FMDV type A than the other mAbs and a commercial mAb. Moreover, the #106 mAb showed no cross-reactivity to inactivated FMDV type South African territories 1, 2, and 3, and low reactivity to inactivated FMDV type O (O1 Manisa). Importantly, the solid-phase competitive ELISA (SPCE) using horseradish peroxidase (HRP)-conjugated #106 mAb detected FMDV type A-specific Abs in sera from FMD type A-vaccinated cattle more effectively than a commercial SPCE. These results suggest that the newly developed FMDV type A-specific mAb might be useful for diagnostic approaches for detecting Abs against FMDV type A.

Hemagglutinin head-specific responses dominate over stem-specific responses following prime boost with mismatched vaccines.

Broadly neutralizing Abs targeting the HA stem can provide broad protection against different influenza subtypes, raising the question of how best to elicit such Abs. We have previously demonstrated that vaccination with pandemic live-attenuated influenza vaccine (pLAIV) establishes immune memory for HA head-specific Abs. Here, we determine the extent to which matched versus mismatched LAIV-inactivated subunit vaccine (IIV) prime-boost vaccination elicits stem-specific memory B cells and Abs. We vaccinated African green monkeys with H5N1 pLAIV-pIIV or H5N1 pLAIV followed by seasonal IIV (sIIV) or with H5N1 pLAIV alone and measured Abs and HA-specific B cell responses. While we observed an increase in stem-specific memory B cells, head-specific memory B cell responses were substantially higher than stem-specific responses and were dominant even following boost with mismatched IIV. Neutralizing Abs against heterologous influenza viruses were undetectable. Head-specific B cells from draining lymph nodes exhibited germinal center markers, while stem-specific B cells found in the spleen and peripheral blood did not. Thus, although mismatched prime-boost generated a pool of stem-specific memory B cells, head-specific B cells and serum Abs substantially dominated the immune response. These findings have implications for including full-length native HA in prime-boost strategies intended to induce stem-specific Abs for universal influenza vaccination.

Rotavirus C: prevalence in suckling piglets and development of virus-like particles to assess the influence of maternal immunity on the disease development

Rotavirus C (RVC) has been detected increasingly in humans and swine in different countries, including the US. It is associated with significant economic losses due to diarrheal disease in nursing piglets. In this study we aimed: (1) to determine the prevalence of RVC in healthy and diarrheic suckling piglets on US farms; and (2) to evaluate if maternal antibody (Ab) levels were associated with protection of newborn suckling piglets against RVC. There was a significantly higher prevalence (p = 0.0002) of litters with diarrhea born to gilts compared with those born to multiparous sows. Of 113 nursing piglet fecal samples tested, 76.1% were RVC RNA positive. Fecal RVC RNA was detected in significantly (p = 0.0419) higher quantities and more frequently in piglets with diarrhea compared with healthy ones (82.5 vs. 69.9%). With the exception of the historic strain Cowden (G1 genotype), field RVC strains do not replicate in cell culture, which is a major impediment for studying RVC pathogenesis and immunity. To circumvent this, we generated RVC virus-like particles (VLPs) for Cowden (G1), RV0104 (G3) and RV0143 (G6) and used them as antigens in ELISA to detect swine RVC Abs in serum and milk from the sows. Using RVC-VLP Ab ELISA we demonstrated that sows with diarrheic litters had significantly lower RVC IgA and IgG Ab titers in milk compared to those with healthy litters. Thus, our data suggest that insufficient lactogenic protection provided by gilts plays a key role in the development of and the increased prevalence of clinical RVC disease.

Adjuvants Enhance the Induction of Germinal Center and Antibody Secreting Cells in Spleen and Their Persistence in Bone Marrow of Neonatal Mice.

Immaturity of the immune system contributes to poor vaccine responses in early life. Germinal center (GC) activation is limited due to poorly developed follicular dendritic cells (FDC), causing generation of few antibody-secreting cells (ASCs) with limited survival and transient antibody responses. Herein, we compared the potential of five adjuvants, namely LT-K63, mmCT, MF59, IC31, and alum to overcome limitations of the neonatal immune system and to enhance and prolong responses of neonatal mice to a pneumococcal conjugate vaccine Pnc1-TT. The adjuvants LT-K63, mmCT, MF59, and IC31 significantly enhanced GC formation and FDC maturation in neonatal mice when co-administered with Pnc1-TT. This enhanced GC induction correlated with significantly enhanced vaccine-specific ASCs by LT-K63, mmCT, and MF59 in spleen 14 days after immunization. Furthermore, mmCT, MF59, and IC31 prolonged the induction of vaccine-specific ASCs in spleen and increased their persistence in bone marrow up to 9 weeks after immunization, as previously shown for LT-K63. Accordingly, serum Abs persisted above protective levels against pneumococcal bacteremia and pneumonia. In contrast, alum only enhanced the primary induction of vaccine-specific IgG Abs, which was transient. Our comparative study demonstrated that, in contrast to alum, LT-K63, mmCT, MF59, and IC31 can overcome limitations of the neonatal immune system and enhance both induction and persistence of protective immune response when administered with Pnc1-TT. These adjuvants are promising candidates for early life vaccination.

Hypergammaglobulinemia and Impaired Transplacental Transfer of Respiratory Syncytial Virus Antibody in Papua New Guinea.

Passively-acquired respiratory syncytial virus (RSV) neutralizing antibody (Ab) can protect against RSV-associated lower respiratory tract illness. Maternal RSV immunization is, therefore, an attractive strategy for protection of very young infants. Vaccines for this purpose are currently being evaluated in clinical trials, but conditions such as preterm birth, placental malaria, maternal hypergammaglobulinemia and HIV infection might threaten this strategy. Each has been shown to impair transplacental Ab transfer for a variety of pathogens, but RSV-specific data are limited. Work in The Gambia demonstrated that placental malaria impaired transplacental transfer of RSV Ab, but a subsequent study in malaria-endemic Papua New Guinea (PNG) indicated that such associations may have been confounded by hypergammaglobulinemia (IgG > 1700 mg/dL). Here we confirm and extend those findings by measuring RSV neutralizing Ab and maternal IgG in sera from a larger cohort of 325 mother/infant pairs in PNG, and demonstrate the applicability of a high-throughput assay for assessment of neutralizing Ab. One-third of mother-infant pairs demonstrated impaired RSV Ab transfer. Infants of hypergammaglobulinemic women were more likely to have both impaired transfer [cord-to-maternal titer ratio <1.0, adjusted odds ratio (OR): 3.36 (95% confidence interval: 1.81-6.30)] and the lowest RSV cord titers [adjusted OR: 5.09 (95% confidence interval: 1.95-13.32, P < 0.001)], but neither outcome was associated with placental malaria. Once maternal RSV vaccines become available, successful implementation will require clear understanding and mitigation of factors that can impair passive protection, necessitating epidemiologic studies of such relationships ahead of vaccine availability. This study underscores the need to focus on hypergammaglobulinemia as a condition of importance.

Immunization against environmental chemical carcinogens: Pro and contra

The problems of immunoprotection from the environmental chemical carcinogens are discussed. The main experimental argument pro active immunization against carcinogens is a possibility of specific mucosal antibodies (Abs) to inhibit the penetration of carcinogens from environment and to stimulate its excretion with the following decreasing of carcinogen-DNA adducts levels. Hypothesis of cancer immunostimulation after active immunization against carcinogens is based on a high cancer risk in persons with high levels of serum Abs specific to environmental carcinogens coupled with high levels of Abs to endogenous steroids stimulating the proliferation of target cells, for example, Abs to benzo[a]pyrene together with Abs to estradiol. The active immunization could increase the cancer risk much more in those persons. The passive immunization could be an alternative safe approach to avoid this problem.

Evaluation of Invasive and Non-Invasive Methods for the Diagnosis of H. pylori in Dyspepsia Patients

Background: H. pylori has been established as the major causative agent of chronic gastritis, and represents the main etiological cause of other gastroduodenal diseases such as peptic ulceration, gastric lymphoma, and gastric cancer. Therefore, screening and treatment of the bacterium is an important strategy for preventing gastric cancer. Objective: To compare some invasive classical histological tests to non-invasive serological antibody and stool antigen tests for the diagnosis of H. pylori infections. Patients and Methods:The study population comprised of 171 patients with symptoms of dyspepsia and other gastritis related symptoms. Three biopsy specimens were taken and collected from the stomach and sent for histopathologic study. H and E staining and modified Giemsa staining were performed on tissue sections of each case. Serology antibody and Stool antigen tests were also used as nan-invasive tests in this study. Results: Four tests had been done to detect the presence of H. pylori Bacteria. The mean age (+ SD) of the studied sample was 43.8 + 14.7 years, ranging from 20 to 74 years. The median was 44 years. The total agreement between the serum Ab test and the stool Ag test was 88.3%. Significant differences were detected between the two tests (p < 0.001). It is evident that the serum Ab test is highly sensitive (sensitivity = 98.4%), but the Predictive value positive (76.3%) was not so high. The Giemsa test was highly specific (specificity = 98.2%), and highly sensitive (sensitivity = 93.5%). Conclusion: The main advantage of histopathology tests is not only restricted to detection purpose, it also can detect any abnormalities of gastric mucosa by bacteria such as peptic ulcer bleeding, atrophic gastritis, intestinal metaplasia, and gastric cancer. The modified Giemsa staining method could be used as a method of choice for the detection of H. pylori due to its sensitivity, simplicity and consistency.

Predicting factors for disappearance of anti-mutated citrullinated vimentin antibodies in sera of patients with rheumatoid arthritis

Objectives: We aimed to determine the predicting factors for disappearance of anti-mutated citrullinated vimentin antibody (anti-MCV Ab) in sera from rheumatoid arthritis (RA) patients.Methods: In 2013, 95 RA patients whose Disease Activity Score with erythrocyte sedimentation rate were moderate to severe (DAS28-ESR ≥3.2) at baseline were enrolled. Titers of anti-MCV Ab and anti-cyclic citrullinated peptide (anti-CCP) Ab for 2013 and 2014 were measured. The association of anti-MCV disappearance with disease activity, treatment, interstitial lung disease (ILD), and serum markers of ILD were retrospectively examined. Predicting factors of anti-MCV disappearance were determined by multivariable analysis.Results: While anti-CCP positivity rate did not change during the year, anti-MCV Ab changed from positive to negative in 18 patients (=19.0%). Continuous biological disease-modifying anti-rheumatic drug use, prednisolone dose (≥5.0 mg daily), and low KL-6 level (<191 U/mL) were determined as predicting factors of anti-MCV disappearance by multivariable analysis. In our cohort, anti-MCV Ab disappearance was not linked to clinical and radiological improvement.Conclusion: Different from anti-CCP Ab, anti-MCV Ab in sera from RA patients can disappear in a year. Some predicting factors for such negative seroconversion were found, whereas clinical significance of anti-MCV Ab disappearance was undetermined.

Vaccination with a Single-Cycle Respiratory Syncytial Virus Is Immunogenic and Protective in Mice

Respiratory syncytial virus (RSV) is the leading cause of severe respiratory tract infection in infants and young children, but no vaccine is currently available. Live-attenuated vaccines represent an attractive immunization approach; however, balancing attenuation while retaining sufficient immunogenicity and efficacy has prevented the successful development of such a vaccine. Recently, a recombinant RSV strain lacking the gene that encodes the matrix (M) protein (RSV M-null) was developed. The M protein is required for virion assembly following infection of a host cell but is not necessary for either genome replication or gene expression. Therefore, infection with RSV M-null produces all viral proteins except M but does not generate infectious virus progeny, resulting in a single-cycle infection. We evaluated RSV M-null as a potential vaccine candidate by determining its pathogenicity, immunogenicity, and protective capacity in BALB/c mice compared with its recombinant wild-type control virus (RSV recWT). RSV M-null-infected mice exhibited significantly reduced lung viral titers, weight loss, and pulmonary dysfunction compared with mice infected with RSV recWT. Despite its attenuation, RSV M-null infection induced robust immune responses of similar magnitude to that elicited by RSV recWT. Additionally, RSV M-null infection generated serum Ab and memory T cell responses that were similar to those induced by RSV recWT. Importantly, RSV M-null immunization provided protection against secondary viral challenge by reducing lung viral titers as efficiently as immunization with RSV recWT. Overall, our results indicate that RSV M-null combines attenuation with high immunogenicity and efficacy and represents a promising novel live-attenuated RSV vaccine candidate.

Human natural killer cell manufacturing using a closed system process for patients with metastatic solid tumors or hematologic malignancies

Background & Aim As potent effectors of the innate immune system natural killer (NK) cells are currently utilized in clinical trials world-wide to treat a variety of hematologic and solid organ malignancies. The ongoing phase I/II study at the National Institutes of Health (08-H-0186) previously utilized open-system processing requiring 60-80 small GREX flasks and single donor AB plasma in the culture medium. We optimized the manufacturing process to generate large numbers of NK cells using closed-system processing with large 5 liter GREX containers and commercially available pooled AB serum. Methods, Results & Conclusion The manufacturing process entails two stages: Preparation of the feeder EBV-transformed lymphoblastoid cell line (LCL) and NK cell culture. LCL are cultured in closed GREX100-CS vessels with XVIVO15 culture media containing 15mM HEPES, 2mM glutamax and 10% of either commercially available pooled AB serum or single donor AB plasma. With one culture vessel capable of generating 8-10 × 108 LCL feeder cells using 600-800mL of culture medium, 3 vessels sufficiently support a full scale culture. LCL number and viability are similar between groups containing serum vs. plasma. In the second stage, NK cell culture is initiated using 3 GREX500-CS with 40 × 106 NK cells and 400 × 106 irradiated LCL feeder cells in 500mL/vessel. Fresh XVIVO20 containing 15mM HEPES, 2mM glutamax, 500IU/mL IL2 and either 10% AB plasma or pooled AB serum is added on days 4, 8, 12 and 17. On day 14, a portion of the cells are harvested and washed for fresh infusion, and the remaining cells are re-seeded into a new vessel for harvest for second infusion on day 19. Day 14 and day 19 harvest generated 10-14 × 109 (1 vessel) and 50-70 × 109 NK cells (4-5 vessels) for fresh infusion, enough to support the target dose level of 1 × 108 (1st harvest) and 5 × 108 (2nd harvest) NK cells/kg. We found no significant differences in cell growth, viability or TRAIL expression when using AB plasma vs. AB serum. However, TRAIL expression was significantly increased when the concentration of the NK cells was kept below 4 × 106 cells/mL during culture. NK cells also demonstrated tumor cell line killing ability in vitro and had increased CD107. In summary, we have developed a new process that improves safety and consistency for culturing NK cells in large numbers for an ongoing clinical trial at the NIH. This process can be easily adapted by cell therapy manufacturing facilities at most academic institutions.

Stage of Gestation at Porcine Epidemic Diarrhea Virus Infection of Pregnant Swine Impacts Maternal Immunity and Lactogenic Immune Protection of Neonatal Suckling Piglets.

During pregnancy, the maternal immune response changes dramatically over the course of gestation. This has implications for generation of lactogenic immunity and subsequent protection in suckling neonates against enteric viral infections. For example, porcine epidemic diarrhea virus (PEDV) is an alphacoronavirus that causes acute diarrhea in neonatal piglets. Due to the high virulence of PEDV and the naïve, immature immune system of neonatal suckling piglets, passive lactogenic immunity to PEDV induced during pregnancy, via the gut-mammary gland (MG)-secretory IgA (sIgA) axis, is critical for piglet protection. However, the anti-PEDV immune response during pregnancy and stage of gestation required to optimally stimulate the gut-MG-sIgA axis is undefined. We hypothesize that there is a gestational window in which non-lethal PEDV infection of pregnant gilts influences maximum lymphocyte mucosal trafficking to the MG, resulting in optimal passive lactogenic protection in suckling piglets. To understand how the stages of gestation affect maternal immune responses to PEDV, three groups of gilts were orally infected with PEDV in the first, second or third trimester. Control (mock) gilts were inoculated with medium in the third trimester. To determine if lactogenic immunity correlated with protection, all piglets were PEDV-challenged at 3–5 days postpartum. PEDV infection of gilts at different stages of gestation significantly affected multiple maternal systemic immune parameters prepartum, including cytokines, B cells, PEDV antibodies (Abs), and PEDV antibody secreting cells (ASCs). Pregnant second trimester gilts had significantly higher levels of circulating PEDV IgA and IgG Abs and ASCs and PEDV virus neutralizing (VN) Abs post PEDV infection. Coinciding with the significantly higher PEDV Ab responses in second trimester gilts, the survival rate of their PEDV-challenged piglets was 100%, compared with 87.2, 55.9, and 5.7% for first, third, and mock litters, respectively. Additionally, piglet survival positively correlated with PEDV IgA Abs and ASCs and VN Abs in milk and PEDV IgA and IgG Abs in piglet serum. Our findings have implications for gestational timing of oral attenuated PEDV maternal vaccines, whereby PEDV intestinal infection in the second trimester optimally stimulated the gut-MG-sIgA axis resulting in 100% lactogenic immune protection in suckling piglets.

Targeting M2e to DEC-205 induces an enhanced serum antibody-dependent heterosubtypic protection against influenza A virus infection

The ectodomain of the influenza A virus (IAV) M2 protein (M2e) is highly conserved, and it represents a promising candidate for the development of an “universal vaccine”. However, the low immunogenicity associated to M2e in a natural infection or in response to seasonal vaccines has led to explore new approaches to enhance it. In recent years, it has become clear that targeting antigens to dendritic cells (DC) is an efficient way to enhance immune responses against pathogens. In this work, the M2e peptide was chemically cross-linked to a monoclonal antibody (mAb) specific for DEC-205 (α-DEC-205:M2e), present on DC. BALB/c mice were inoculated subcutaneously (s.c.) three times with the conjugate equivalent to 1 µg of M2e, in the presence of polyinosinic-polycytidylic acid (poly I:C) as adjuvant. As controls, other groups of mice were inoculated under the same conditions with M2e cross-linked to an isotype control mAb (isotype:M2e), 5 µg of free M2e peptide, ovalbumin (OVA) cross-linked to the α-DEC-205 mAb (α-DEC-205:OVA) or poly I:C alone. Immunization with α-DEC-205-M2e induced high levels of serum antibodies (Abs) compared to isotype:M2e or to free M2e peptide, and in all cases IgG1 was predominant over IgG2a Abs. Furthermore, immunization with the α-DEC-205:M2e conjugate did not prevent morbidity, but it induced up to 76% protection against a heterosubtypic IAV lethal challenge. Contrasting with the 20 to 40% protection induced by isotype:M2e or by free M2e peptide. The protection induced by α-DEC-205:M2e conjugate was dependent on non-neutralizing serum Abs and independent of effector CD4+ T cells. These results show that targeting M2e to DEC-205 is a very effective alternative to induce strong heterosubtypic protection against an IAV infection.

OC 8244 QUANTITATIVE LATERAL FLOW ASSAY FOR DETECTION OFM. LEPRAEINFECTION USING FINGERSTICK BLOOD

BackgroundLeprosy is a debilitating, infectious disease caused byMycobacterium lepraeleading to skin and nerve damage and often lifelong handicaps. The unabated rate of new leprosy case detection indicates that transmission ofM. lepraeis persistent and that current measures for prevention and multidrug therapy (MDT) are insufficient. Contact withM. leprae-infected individuals is a risk factor for development of leprosy. Thus, detection ofM. leprae-infected individuals without clinical symptoms, allowing informed decision making on who needs treatment at a preclinical stage, is vital to interrupt transmission and can help prevent leprosy.Immunoprophylaxis by vaccination or post-exposure prophylaxis (PEP) with antibiotics provide effective strategies for the prevention of leprosy. To target individuals unknowingly spreading leprosy bacilli, methods allowing objective measurement ofM. lepraeinfection are needed. Besides antibody (Ab) levels that correspond with bacterial load and higher risk of progression to leprosy, detection of cytokine profiles can provide significant added value to identify infection.MethodsQuantitative detection of anti-PGL-I IgM antibodies, and cytokines such as IP-10 was performed on lateral flow (LF) test strips utilising the luminescent up-converting particle (UCP) technology. Precise amounts of fingerstick (FS)-blood samples were collected using disposable heparinised capillaries. Ab and cytokine levels in both FS-blood and serum from „leprosy patients in South-Africa, Brazil, Bangladesh and the Netherlands and (their) contacts were measured using a portable reader.ResultsExcellent correlation was demonstrated between data for anti-PGL-I IgM Ab and cytokines obtained with serum and FS blood from the same individuals.ConclusionThe quantitative UCP-LF test strips detecting anti-PGL-I IgM Ab and cytokines for the detection ofM. lepraeinfection is compatible with fingerstick blood allowing near-patient testing and immediate appropriate follow-up counselling.

A Combined YopB and LcrV Subunit Vaccine Elicits Protective Immunity against Yersinia Infection in Adult and Infant Mice.

Yersinia enterocolitica causes a severe enteric infection in infants and young children. There is no vaccine approved for use in humans. We investigated the immunogenicity and protective capacity of Yersinia YopB, a conserved type III secretion system protein, alone or combined with LcrV in adult mice immunized intranasally. YopB or LcrV (5 μg) administered with the Escherichia coli double mutant heat-labile toxin (dmLT) adjuvant afforded modest (10-30%) protection against lethal Y. enterocolitica oral infection. The combination of YopB and LcrV (5 μg each) dramatically improved vaccine efficacy (70-80%). Additionally, it afforded complete protection against Y. pestis pulmonary infection. Immunization with YopB/LcrV+dmLT resulted in Ag-specific serum IgG, systemic and mucosal Ab-secreting cells, as well as IFN-γ, TNF-α, IL-2, IL-6, IL-17A, and KC production by spleen cells. Serum Abs elicited by YopB/LcrV+dmLT had enhanced bactericidal and opsonophagocytic killing activity. After Y. enterocolitica challenge, YopB/LcrV+dmLT-vaccinated mice exhibited intact intestinal tissue, active germinal centers in mesenteric lymph nodes, IgG+ and IgA+ plasmablasts in the lamina propria, and Abs in intestinal fluid. On the contrary, complete tissue destruction and abscesses were seen in placebo recipients that succumbed to infection. Mice immunized as infants with YopB+dmLT or LcrV+dmLT achieved 60% protection against lethal Y. enterocolitica infection, and vaccine efficacy increased to 90-100% when they received YopB/LcrV+dmLT. YopB+dmLT also afforded substantial (60%) protection when administered intradermally to infant mice. YopB/LcrV+dmLT is a promising subunit vaccine candidate with the potential to elicit broad protection against Yersinia spp.

IL-33 enhances the kinetics and quality of the antibody response to a DNA and protein-based HIV-1 Env vaccine

Induction of a sustained and broad antibody (Ab) response is a major goal in developing a protective HIV-1 vaccine. DNA priming alone shows reduced levels of immunogenicity; however, when combined with protein boosting is an attractive vaccination strategy for induction of humoral responses. Using the VC10014 DNA and protein-based vaccine consisting of HIV-1 envelope (Env) gp160 plasmids and trimeric gp140 proteins derived from an HIV-1 clade B infected subject who developed broadly neutralizing serum Abs, and which has been previously demonstrated to induce Tier 2 heterologous neutralizing Abs in rhesus macaques, we evaluated whether MPLA and IL-33 when administered during the DNA priming phase enhances the humoral response in mice. The addition of IL-33 during the gp160 DNA priming phase resulted in high titer gp120-specific plasma IgG after the first immunization. The IL-33 treated mice had higher plasma IgG Ab avidity, breadth, and durability after DNA and protein co-immunization with alum adjuvant as compared to MPLA and alum only treated mice. IL-33 was also associated with a significant IgM Env-specific response and expansion of peritoneal and splenic B-1b B cells. These results indicate that DNA priming in the presence of exogenous IL-33 qualitatively alters the HIV-1 Env-specific humoral response, improving the kinetics and breadth of potentially protective Ab.