Role Of Antibodies In Immunity Research Articles

Access to ultra-long IgG CDRH3 bovine antibody sequences using short read sequencing technology

The advances in high-throughput DNA sequencing and recombinant antibody technologies has presented new methods for characterizing antibody repertoires and significantly increased our understanding on the functional role of antibodies in immunity and their use in diagnostics, vaccine antigen design and as biological therapeutics. A subset of Bos taurus antibodies possesses unique ultra-long third complementary-determining region of the heavy chain (CDRH3) and are of special interest because they are thought to have unique functional abilities of broadly neutralizing properties – a functional role that has not been fully explored in vaccine development. Next generation sequencing technologies that are widely used to profile immunoglobulin (Ig) repertoires are based on short-read methods such as the Illumina technology. Although this technology has worked well in sequencing Ig V-D-J regions of most jawed vertebrates, it has faced serious technical challenges with sequencing regions in bovine Ig bearing ultra-long CDRH3 sequences, which are longer than 120 bp. To overcome this limitation, we have developed a sequencing strategy based on nested PCR products that allows sequence assembly of full-length bovine Ig heavy-chain (IgH) V-D-J regions. We have used this strategy to sequence IgH V-D-J regions of two Bos indicus breeds, Ankole and Boran. We confirm the presence of ultra-long CDRH3 sequences in IgG transcripts in both African cattle breeds, and provide preliminary evidence for differences and preferences in germline VH, DH and JH allele gene usage as well as differences in the length of the VH region in the two bovine breeds. Our method provides tools that should allow more robust analyses of ultra-long CDRH3 sequences aiding antibody and epitope discovery in different cattle breeds and their role in mediating immunity.

Naturally induced humoral response against Plasmodium vivax reticulocyte binding protein 2P1

BackgroundPlasmodium vivax is the most prevalent malaria parasite in many countries. A better understanding of human immunity to this parasite can provide new insights for vaccine development. Plasmodium vivax Reticulocyte Binding Proteins (RBPs) are key parasite proteins that interact with human proteins during erythrocyte invasion and are targets of the human immune response. The aim of this study is to characterize the human antibody response to RBP2P1, the most recently described member of the RBP family.MethodsThe levels of total IgG and IgM against RBP2P1 were measured using plasmas from 68 P. vivax malaria patients and 525 villagers in a malarious village of western Thailand. The latter group comprises asymptomatic carriers and healthy uninfected individuals. Subsets of plasma samples were evaluated for anti-RBP2P1 IgG subtypes and complement-fixing activity.ResultsAs age increased, it was found that the level of anti-RBP2P1 IgG increased while the level of IgM decreased. The main anti-RBP2P1 IgG subtypes were IgG1 and IgG3. The IgG3-seropositive rate was higher in asymptomatic carriers than in patients. The higher level of IgG3 was correlated with higher in vitro RBP2P1-mediated complement fixing activity.ConclusionsIn natural infection, the primary IgG response to RBP2P1 was IgG1 and IgG3. The predominance of these cytophilic subtypes and the elevated level of IgG3 correlating with complement fixing activity, suggest a possible role of anti-RBP2P1 antibodies in immunity against P. vivax.

In vitro spleen cell cytokine responses of adult mice immunized with a recombinant PorA (major outer membrane protein [MOMP]) from Campylobacter jejuni

There is no information on cytokine profiles for use as markers of protection in Campylobacter jejuni infection. To study this, we used outer membrane protein (MOMP [PorA]) as the vaccine for protection and spleen cell cytokines as markers of protection. We cloned and expressed porA from C. jejuni111 and immunized mice by the intraperitoneal route. Subsequently, mice were orally challenged with live C. jejuni 111. The vaccine induced protection as evidenced by reduced fecal excretion of C. jejuni111. Cytokines were measured in vitro after stimulation of spleen cells with MOMP. The levels of pro-inflammatory cytokines, IL-12, TNF-α, IL-17A and IL-17F were similar in control and test mice. The levels of pro-inflammatory cytokines, IL-2 and IFN-γ were higher in control mice than in test mice, and the levels of pro-inflammatory cytokines, IL-8 and IL-1β were higher in test mice than in control mice. Among the two anti-inflammatory cytokines, the levels were similar for IL-10 but higher for IL-4 in test mice than in control mice. Ratios of pro-inflammatory to anti-inflammatory cytokines showed a bias towards an anti-inflammatory response in favor of antibody production reflecting the role of antibodies in immunity. Cytokine production patterns by spleen cells may be used as markers of protection in the mouse model.

IFNγ is Required for Optimal Antibody-Mediated Immunity against Genital Chlamydia Infection.

Defining the mechanisms of immunity conferred by the combination of antibody and CD4+ T cells is fundamental to designing an efficacious chlamydial vaccine. Using the Chlamydia muridarum genital infection model of mice, which replicates many features of human C. trachomatis infection and avoids the characteristic low virulence of C. trachomatis in the mouse, we previously demonstrated a significant role for antibody in immunity to chlamydial infection. We found that antibody alone was not protective. Instead, protection appeared to be conferred through an undefined antibody-cell interaction. Using gene knockout mice and in vivo cellular depletion methods, our data suggest that antibody-mediated protection is dependent on the activation of an effector cell population in genital tract tissues by CD4+ T cells. Furthermore, the CD4+ T cell-secreted cytokine gamma interferon (IFN-γ) was found to be a key component of the protective antibody response. The protective function of IFN-γ was not related to the immunoglobulin class or to the magnitude of the Chlamydia-specific antibody response or to recruitment of an effector cell population to genital tract tissue. Rather, IFN-γ appears to be necessary for activation of the effector cell population that functions in antibody-mediated chlamydial immunity. Our results confirm the central role of antibody in immunity to chlamydia reinfection and demonstrate a key function for IFN-γ in antibody-mediated protection.

The Intriguing Case of KMP and KMR

<h3>Abstract</h3> <h3>Background</h3> Accurate measurement of antibodies is a necessary tool for assessing exposure to SARS-CoV-2 and facilitating understanding of the role of antibodies in immunity. Most assays are qualitative in nature and employ a threshold to determine presence of antibodies. Semi-quantitative assays are now available. Here we evaluate the semi-quantitative SARS-CoV-2 IgG II (anti-spike (S)) assay. We aim to reassess the seroprevalence using anti-S assay and subsequently compare it to the previously measured IgG (anti-nucleoprotein (N)) in health care workers at an academic medical center in Boston. <h3>Methods</h3> 1743 serum samples from HCWs at Boston Medical Center were analyzed for SARS-CoV-2 anti-S IgG and IgM using the Abbott SARS-CoV-2 IgG II and□Abbott AdviseDx□SARS-CoV-2 IgM assay, respectively. Precision, linearity, positive and negative concordance with prior RT-PCR test were evaluated for anti-S IgG. Seroprevalence and its association with demographics variables was also assessed. <h3>Results</h3> Linearity and precision results were clinically acceptable. The positive and negative concordance for anti-S IgG with RT-PCR was 88.2% (95% CI: 79.4% - 94.2%) and 97.43% (95% CI: 95.2% - 98.8%), respectively. Overall, 126 (7.2%) of 1,743 participants were positive by anti-S IgG. Among the 1302 participants with no prior RT-PCR, 40 (3.1%) were positive for anti-S IgG antibody. The original agreement in this population with the qualitative, anti-N IgG assay was 70.6%. Upon optimizing the threshold from 1.4 to 0.49 S/CO of the anti-N IgG assay, the positive agreement of the assay increases to 84.7%. <h3>Conclusion</h3> The anti-S IgG assay demonstrated reproducible and reliable measurements. This study highlights the presence of asymptomatic transmission among individuals with no prior history of positive RT-PCR. It also highlights the need for optimizing thresholds of the qualitative SARS-CoV-2 IgG assay for better agreement between assays by the same vendor.

Role of antibody in immunity and control of chicken coccidiosis

Research has been carried out worldwide to try to elucidate the mechanism of protective immunity against coccidiosis. It was concluded from early studies that cellular immunity is the key to protection against Eimeria, whereas humoral immunity plays a very minor role in resistance against infection. By contrast, other studies have pointed towards the ability of antibody to block parasite invasion, development and transmission and to provide passive and maternal immunity against challenge infection. Herein, recent results demonstrate the ability of antibodies (raised by live immunization or against purified stage-specific Eimeria antigens) to inhibit parasite development in vitro and in vivo and readdress the question of the role of antibody in protection against coccidiosis.

Immunity to Microbes: Lessons from Primary Immunodeficiencies

Primary immunodeficiency diseases (PIDs) represent a large and heterogeneous group of more than 120 different entities, most of which have now been genetically characterized (77). Increased susceptibility to infections is the predominant manifestation of almost all forms of PID, particularly in infants and children, demonstrating the paramount importance of the immune system in defense against infection. It has long been known that the nature of an immune defect is related to the etiology of an infection. Prime examples are recurrent respiratory infections with pyogenic bacteria in patients with antibody deficiencies, opportunistic infections with fungi and viruses in infants with SCID (severe combined immunodeficiency), Neisseria meningitidis infections as a hallmark of defects in late-complement components, recurrent staphylococcal infections in patients with neutrophil disorders, and susceptibility to weakly virulent mycobacterial diseases and to Salmonella in patients with deficiencies of the interleukin-12 (IL-12)/IL-23-gamma interferon (IFN-γ) axis. Studies of PID patients have actually contributed to clarification of the anti-infection roles of several mechanisms and components of the immune response, as PIDs offer unique opportunities to link phenotypes to immunological functions and to ascribe various classes of immunity to defenses against different microbes. Thus, studies of agammaglobulinemic patients were crucial in elucidating the role of antibodies in immunity to extracellular bacteria and enteroviruses, as were studies of children with Kostmann's syndrome (congenital severe neutropenia) and chronic granulomatous disease (CGD) in defining the critical role of neutrophils and studies of SCID patients in showing the relevance of T-cell immunity in resistance to intracellular pathogens. More recently, as clinical phenotypes are being mapped to gene defects, respective pathophysiologies can be better understood, often with the help of murine knockout models. Here we offer an observational approach to host/parasite relationships, based on clinical features of PID patients. After an exhaustive review of the main infectious manifestations of PID patients described in large published series as well as in our own series, we propose a novel classification of PIDs according to the degrees of clinical susceptibility to infectious agents observed with PID patients, attempting to link selective susceptibility to specific mechanisms and to established genetic defects. Evidence for a causal association between a particular infection and a given PID is available in some cases, but in others, only a small number of patients have been studied. The data were organized in tables that classify susceptibility to each infection as high (when it is a major manifestation of disease), intermediate (when it appears in some cases but not as a rule), and low (when it is seldom seen). We believe that organizing available information in this manner may also be helpful for the physician, whose identification of a given infection may help determine a putative immunodeficiency.

Role of antibodies in immunity to Bordetella infections.

The persistence of Bordetella pertussis and B. parapertussis within vaccinated populations and the reemergence of associated disease highlight the need to better understand protective immunity. The present study examined host immunity to bordetellae and addressed potential concerns about the mouse model by using a comparative approach including the closely related mouse pathogen B. bronchiseptica. As previously observed with B. pertussis, all three organisms persisted throughout the respiratory tracts of B-cell-deficient mice, indicating that B cells are required for bacterial clearance. However, adoptively transferred antibodies rapidly cleared B. bronchiseptica but not human pathogens. These results obtained with the mouse model are consistent with human clinical observations, including the lack of correlation between antibody titers and protection, as well as the limited efficacy of intravenous immunoglobulin treatments against human disease. Together, this evidence suggests that the mouse model accurately reflects substantial differences between immunities to these organisms. Although both B. pertussis and B. parapertussis are more closely related to B. bronchiseptica than they are to each other, they share the ability to resist rapid clearance from the lower respiratory tract by adoptively transferred antibodies, an adaptation that correlates with their emergence as human pathogens that circulate within vaccinated populations.

Attenuated parasites and the development of an erythrocytic-stage vaccine

Asexual-stage vaccine candidates may be identified by recognition of antibodies to them in the sera of naturally immune individuals. Once identified, recombinant molecules expressing the relevant antigen can be produced, although such recombinant molecules only seem to be effective at inducing immunity if mixed with adjuvant. More information is needed about the role of antibodies in immunity to malaria. In an animal model, that of Plasmodium berghei in mice, a fairly effective immune response can be produced by inoculating mice with live, proliferating parasites and then keeping the infections subclinical, by drug treatment, for 5 weeks. However, the resultant ‘immune1 individuals carry small numbers of parasites despite the presence of antibody (premunition). Repeated challenge infections are limited by the hosts’ immune responses but sterile immunity is not observed, The immunity that is established only fades in the absence of the parasite, In contrast, inoculation with preparations of disrupted parasites, which do not seem to contain all the antigenic information of the living parasites, do not lead to an immune response which limits parasitaemias. These observations may be the result of antigenic variation. Immunity induced in mice by live, attenuated parasites (but not by extracts) protects against challenge with virulent parasites. Immunity against the attenuated but not the virulent parasite can be transferred by inoculating naive mice with spleen cells from the immunized mice. The mice given spleen cells can then be protected against the virulent parasite by challenge with proliferating, attenuated parasites (but not with extracts). Immune B cells from the immune donor and non-immune CD4 cells in the naive recipient are essential for transfer of immunity.

The role of mucosal antibody in immunity to infectious laryngotracheitis virus in chickens

The role of mucosal antibody in recovery from a primary infection and resistance to reinfection with infectious laryngotracheitis (ILT) herpesvirus was studied in bursectomized chickens, which were unable to synthesize specific antibodies. Viral antigen in the infected trachea was assessed by indirect immunofluorescence on tissue sections and by ELISA. The ability of bursectomized chickens to resolve primary infections as effectively as intact chickens and of vaccinated-bursectomized chickens to prevent the replication of challenge virus without the participation of mucosal antibody, is evidence for the importance of local cell-mediated rather than humoral immune mechanisms in the outcome of infection with ILT virus.

Chronic giardiasis in B-cell-deficient mice expressing the xid gene.

The role of antibody in immunity to Giardia muris infection was investigated by studying B-cell-deficient CBA/N mice expressing the xid gene. After gastric administration of infective G. muris cysts, CBA/N male and female mice developed prolonged G. muris infection, whereas BALB/c mice eliminated their infection in 6 to 8 weeks. Male F1 progeny obtained from matings between female CBA/N mice and male BALB/c mice expressed the xid gene and developed prolonged infections. In contrast, all other F1 progeny of CBA/N and BALB/c matings, which did express the xid gene, eliminated G. muris. The link between the xid gene and prolonged infection was confirmed by studies of C57BL/6 mice congenic for the xid gene. When compared with BALB/c or F1 mice, CBA/N mice produced large quantities of immunoglobulin A (IgA) anti-G. muris antibody in serum and gut secretions during prolonged infection. Serum IgG anti-G. muris antibody levels were reduced in CBA/N and F1 male mice that expressed the xid gene. The inability of xid mice to eliminate G. muris is consistent with the importance of antibody in the development of immunity to G. muris. We hypothesize that mice bearing the xid gene fail to produce IgA antibody of appropriate specificity to an antigen or antigens whose recognition by antibody is critical for successful elimination of the parasite.

The role of antibodies in immunity against theileria annulata infection in cattle

The role of antibodies in protecting cattle against Theileria annulata infection was investigated. It was found that serum samples from immune cattle had a neutralizing effect on the sporozoites preventing in this way the invasion of lymphocytes. However, the same antiserum neither caused lysis of macroschizont- infected lymphoblastoid cells nor inhibited their proliferation in vitro. Free merozoites but not the infected erythrocytes were opsonized by immune serum. In addition, complement alone, without antibody participation, was able to lyse free merozoites. The importance of humoral factors in immunity to T. annulata infection is discussed.

Parasitological and immunological aspects of Trypanosoma cruzi infection in nude rats.

The role of the thymus on immunity of rats against Trypanosoma cruzi infection was investigated in vivo. The athymic (nu/nu) rats were shown to be significantly more susceptible to the acute phase of the infection than the control nu/+ rats, as measured by increased parasitemia and mortality. Specific anti-T. cruzi antibodies, complement, IgM and IgG2a serum levels were determined. The results would indicate the essential role of antibodies in immunity to acute Chagas' disease through T-dependent immune response.

Experimental cholera in infant mice: protective effects of antibody.

The protective role of antibody in immunity to experimental infection of five-tosix-day-old infant mice with Vibrio cholerae has been confirmed. Antibody does not protect two- to three-day-old mice, and mice six- to eight-weeks of age are no longer susceptible to the infection. The results of our studies demonstrate that antibody operates by a direct antibacterial mechanism acting in the intestine.

An experimental study of the role of antibodies in immunity to tumors

This work is devoted to the study of the role of the antibodies in induction of immunity to Brown-Pearce carcinoma. Serum or splenic tissue and lymph node tissue, obtained from rabbits immune to the tumor was introduced to rabbits. The subsequent inoculation of the tumor tissue to experimental animals was connected in a number of cases with complete or partial inhibition of the tumor growth. These data demonstrate the significance of the antibodies in the mechanism of antitumor protection of the organism.

The role of antibodies in immunity to transplanted leukæmia in mice

The role of antibodies in immunity to transplanted leukæmia in mice