scholarly journals Role of Opsonophagocytosis in Immune Protection against Malaria

Vaccines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 264
Author(s):  
Wolfgang W. Leitner ◽  
Megan Haraway ◽  
Tony Pierson ◽  
Elke S. Bergmann-Leitner
Keyword(s):  
Protective Immunity ◽  
Defense Mechanisms ◽  
Vaccine Development ◽  
Immune Defense ◽  
Complement Components ◽  
Correlates Of Protection ◽  
Immune Correlates ◽  
Antibody Titers ◽  
Simple Measurement ◽  
Humoral Responses

The quest for immune correlates of protection continues to slow vaccine development. To date, only vaccine-induced antibodies have been confirmed as direct immune correlates of protection against a plethora of pathogens. Vaccine immunologists, however, have learned through extensive characterizations of humoral responses that the quantitative assessment of antibody responses alone often fails to correlate with protective immunity or vaccine efficacy. Despite these limitations, the simple measurement of post-vaccination antibody titers remains the most widely used approaches for vaccine evaluation. Developing and performing functional assays to assess the biological activity of pathogen-specific responses continues to gain momentum; integrating serological assessments with functional data will ultimately result in the identification of mechanisms that contribute to protective immunity and will guide vaccine development. One of these functional readouts is phagocytosis of antigenic material tagged by immune molecules such as antibodies and/or complement components. This review summarizes our current understanding of how phagocytosis contributes to immune defense against pathogens, the pathways involved, and defense mechanisms that pathogens have evolved to deal with the threat of phagocytic removal and destruction of pathogens.

scholarly journals Anterior Chamber-Associated Immune Deviation (ACAID): An Acute Response to Ocular Insult Protects from Future Immune-Mediated Damage?

2009 ◽  
Vol 1 ◽  
pp. OED.S2858 ◽  
Author(s):  
Robert E. Cone ◽  
Roshan Pais
Keyword(s):  
Immune Response ◽  
Anterior Chamber ◽  
Defense Mechanisms ◽  
Immune Defense ◽  
Ocular Tissue ◽  
Immune Deviation ◽  
Acute Response ◽  
Cell Mediated Immune Response ◽  
A Cell ◽  
Humoral Responses

The “immune privilege” that inhibits immune defense mechanisms that could lead to damage to sensitive ocular tissue is based on the expression of immunosuppressive factors on ocular tissue and in ocular fluids. In addition to this environmental protection, the injection of antigen into the anterior chamber or infection in the anterior chamber induces a systemic suppression of potentially damaging cell-mediated and humoral responses to the antigen. Here we discuss evidence that suggests that Anterior Chamber-Associated Immune Deviation (ACAID)a is initiated by an ocular response to moderate inflammation that leads to a systemic immunoregulatory response. Injection into the anterior chamber induces a rise in TNF-α and MCP-1 in aqueous humor and an infiltration of circulating F4/80+ monocytes that home to the iris. The induction of ACAID is dependent on this infiltration of circulating monocytes that eventually emigrate to the thymus and spleen where they induce regulatory T cells that inhibit the inductive or effector phases of a cell-mediated immune response. ACAID therefore protects the eye from the collateral damage of an immune response to infection by suppressing a future potentially damaging response to infection.

scholarly journals Shigella -Specific Immune Profiles Induced after Parenteral Immunization or Oral Challenge with Either Shigella flexneri 2a or Shigella sonnei

mSphere ◽  
2021 ◽  
Author(s):  
Kristen A. Clarkson ◽  
Chad K. Porter ◽  
Kawsar R. Talaat ◽  
Robert W. Frenck ◽  
Cristina Alaimo ◽  
...  
Keyword(s):  
Immune Responses ◽  
Protective Immunity ◽  
Shigella Flexneri ◽  
Severe Disease ◽  
Oral Challenge ◽  
Immune Markers ◽  
Correlates Of Protection ◽  
Immune Correlates ◽  
Shigella Flexneri 2A ◽  
Parenteral Immunization

Although immune correlates of protection have yet to be defined for shigellosis, prior studies have demonstrated that Shigella infection provides protection against reinfection in a serotype-specific manner. Therefore, it is likely that subjects with moderate to severe disease post-oral challenge would be protected from a homologous rechallenge, and investigating immune responses in these subjects may help identify immune markers associated with the development of protective immunity.

scholarly journals Protective efficacy of rhesus adenovirus COVID-19 vaccines against mouse-adapted SARS-CoV-2

2021 ◽  
Author(s):  
Lisa H. Tostanoski ◽  
Lisa E. Gralinski ◽  
David R. Martinez ◽  
Alexandra Schaefer ◽  
Shant H. Mahrokhian ◽  
...  
Keyword(s):  
Viral Replication ◽  
Protective Efficacy ◽  
Neutralizing Antibody ◽  
Wild Type ◽  
Adenovirus Serotype ◽  
Vaccine Candidates ◽  
Correlates Of Protection ◽  
Immune Correlates ◽  
Antibody Titers ◽  
Adenovirus Vectors

The global COVID-19 pandemic has sparked intense interest in the rapid development of vaccines as well as animal models to evaluate vaccine candidates and to define immune correlates of protection. We recently reported a mouse-adapted SARS-CoV-2 virus strain (MA10) with the potential to infect wild-type laboratory mice, driving high levels of viral replication in respiratory tract tissues as well as severe clinical and respiratory symptoms, aspects of COVID-19 disease in humans that are important to capture in model systems. We evaluated the immunogenicity and protective efficacy of novel rhesus adenovirus serotype 52 (RhAd52) vaccines against MA10 challenge in mice. Baseline seroprevalence is lower for rhesus adenovirus vectors than for human or chimpanzee adenovirus vectors, making these vectors attractive candidates for vaccine development. We observed that RhAd52 vaccines elicited robust binding and neutralizing antibody titers, which inversely correlated with viral replication after challenge. These data support the development of RhAd52 vaccines and the use of the MA10 challenge virus to screen novel vaccine candidates and to study the immunologic mechanisms that underscore protection from SARS-CoV-2 challenge in wild-type mice. Importance We have developed a series of SARS-CoV-2 vaccines using rhesus adenovirus serotype 52 (RhAd52) vectors, which exhibits a lower seroprevalence than human and chimpanzee vectors, supporting their development as novel vaccine vectors or as an alternative Ad vector for boosting. We sought to test these vaccines using a recently reported mouse-adapted SARS-CoV-2 (MA10) virus to i) evaluate the protective efficacy of RhAd52 vaccines and ii) further characterize this mouse-adapted challenge model and probe immune correlates of protection. We demonstrate RhAd52 vaccines elicit robust SARS-CoV-2-specific antibody responses and protect against clinical disease and viral replication in the lungs. Further, binding and neutralizing antibody titers correlated with protective efficacy. These data validate the MA10 mouse model as a useful tool to screen and study novel vaccine candidates, as well as the development of RhAd52 vaccines for COVID-19.

scholarly journals Human Cytomegalovirus Congenital (cCMV) Infection Following Primary and Nonprimary Maternal Infection: Perspectives of Prevention through Vaccine Development

Vaccines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 194
Author(s):  
Giuseppe Gerna ◽  
Daniele Lilleri
Keyword(s):  
Human Cytomegalovirus ◽  
Subunit Vaccine ◽  
Vaccine Development ◽  
Maternal Infection ◽  
Major Step ◽  
Congenital Cytomegalovirus ◽  
Partial Protection ◽  
Correlates Of Protection ◽  
Immune Correlates ◽  
Hyperimmune Globulin

Congenital cytomegalovirus (cCMV) might occur as a result of the human cytomegalovirus (HCMV) primary (PI) or nonprimary infection (NPI) in pregnant women. Immune correlates of protection against cCMV have been partly identified only for PI. Following either PI or NPI, HCMV strains undergo latency. From a diagnostic standpoint, while the serological criteria for the diagnosis of PI are well-established, those for the diagnosis of NPI are still incomplete. Thus far, a recombinant gB subunit vaccine has provided the best results in terms of partial protection. This partial efficacy was hypothetically attributed to the post-fusion instead of the pre-fusion conformation of the gB present in the vaccine. Future efforts should be addressed to verify whether a new recombinant gB pre-fusion vaccine would provide better results in terms of prevention of both PI and NPI. It is still a matter of debate whether human hyperimmune globulin are able to protect from HCMV vertical transmission. In conclusion, the development of an HCMV vaccine that would prevent a significant portion of PI would be a major step forward in the development of a vaccine for both PI and NPI.

scholarly journals Antibody-dependent enhancement of severe dengue disease in humans

Science ◽  
2017 ◽  
Vol 358 (6365) ◽  
pp. 929-932 ◽  
Author(s):  
Leah C. Katzelnick ◽  
Lionel Gresh ◽  
M. Elizabeth Halloran ◽  
Juan Carlos Mercado ◽  
Guillermina Kuan ◽  
...  
Keyword(s):  
Vaccine Development ◽  
Severe Disease ◽  
Severe Dengue ◽  
Antibody Dependent Enhancement ◽  
Dengue Disease ◽  
Symptomatic Disease ◽  
Immune Correlates ◽  
Antibody Titers ◽  
Approaches To Study

For dengue viruses 1 to 4 (DENV1-4), a specific range of antibody titer has been shown to enhance viral replication in vitro and severe disease in animal models. Although suspected, such antibody-dependent enhancement of severe disease has not been shown to occur in humans. Using multiple statistical approaches to study a long-term pediatric cohort in Nicaragua, we show that risk of severe dengue disease is highest within a narrow range of preexisting anti-DENV antibody titers. By contrast, we observe protection from all symptomatic dengue disease at high antibody titers. Thus, immune correlates of severe dengue must be evaluated separately from correlates of protection against symptomatic disease. These results have implications for studies of dengue pathogenesis and for vaccine development, because enhancement, not just lack of protection, is of concern.

scholarly journals Novel Modified Vaccinia Virus Ankara Vector Expressing Anti-apoptotic GeneB13RDelays Apoptosis and Enhances Humoral Responses

2018 ◽  
Vol 93 (5) ◽  
Author(s):  
Lynette S. Chea ◽  
Linda S. Wyatt ◽  
Sailaja Gangadhara ◽  
Bernard Moss ◽  
Rama R. Amara
Keyword(s):  
Vaccinia Virus ◽  
Vaccine Development ◽  
Modified Vaccinia Virus Ankara ◽  
Immunodeficiency Virus ◽  
Antibody Titers ◽  
Infected Cells ◽  
Induced Apoptosis ◽  
Humoral Responses ◽  
Antigen Presenting

ABSTRACTModified vaccinia virus Ankara (MVA), an attenuated poxvirus, has been developed as a potential vaccine vector for use against cancer and multiple infectious diseases, including human immunodeficiency virus (HIV). MVA is highly immunogenic and elicits strong cellular and humoral responses in preclinical models and humans. However, there is potential to further enhance the immunogenicity of MVA, as MVA-infected cells undergo rapid apoptosis, leading to faster clearance of recombinant antigens and potentially blunting a greater response. Here, we generated MVA-B13Rby replacing the fragmented181R/182Rgenes of MVA with a functional anti-apoptotic gene,B13R, and confirmed its anti-apoptotic function against chemically induced apoptosisin vitro. In addition, MVA-B13Rshowed a significant delay in induction of apoptosis in muscle cells derived from mice and humans, as well as in plasmacytoid dendritic cells (pDCs) and CD141+DCs from rhesus macaques, compared to the induction of apoptosis in MVA-infected cells. MVA-B13Rexpressing simian immunodeficiency virus (SIV) Gag and Pol and HIV envelope (SHIV) (MVA-B13R/SHIV) produced higher levels of envelope in the supernatants than MVA/SHIV-infected DF-1 cellsin vitro. Immunization of BALB/c mice showed induction of higher levels of envelope-specific antibody-secreting cells and memory B cells, higher IgG antibody titers, and better persistence of antibody titers with MVA-B13R/SHIV than with MVA/SHIV. Gene set enrichment analysis of draining lymph node cells from day 1 after immunization showed negative enrichment for interferon responses in MVA-B13R/SHIV-immunized mice compared to the responses in MVA/SHIV-immunized mice. Taken together, these results demonstrate that restoringB13Rfunctionality in MVA significantly delays MVA-induced apoptosis in muscle and antigen-presenting cellsin vitroand augments vaccine-induced humoral immunity in mice.IMPORTANCEMVA is an attractive viral vector for vaccine development due to its safety and immunogenicity in multiple species and humans even under conditions of immunodeficiency. Here, to further improve the immunogenicity of MVA, we developed a novel vector, MVA-B13R, by replacing the fragmented anti-apoptotic genes181R/182Rwith a functional version derived from vaccinia virus,B13R. Our results show that MVA-B13Rsignificantly delays apoptosis in antigen-presenting cells and muscle cellsin vitroand augments vaccine-induced humoral immunity in mice, leading to the development of a novel vector for vaccine development against infectious diseases and cancer.

scholarly journals Potential SARS-CoV-2 Immune Correlates of Protection in Infection and Vaccine Immunization

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 138
Author(s):  
Yongjun Sui ◽  
Yonas Bekele ◽  
Jay A. Berzofsky
Keyword(s):  
Immune Responses ◽  
Neutralizing Antibody ◽  
Current Data ◽  
Innate Immune ◽  
Type I Interferons ◽  
Type I ◽  
Risk Of Infection ◽  
Correlates Of Protection ◽  
Immune Correlates ◽  
Antibody Titers

Both SARS-CoV-2 infections and vaccines induce robust immune responses. Current data suggested that high neutralizing antibody titers with sustained Th1 responses might correlate with protection against viral transmission and disease development and severity. In addition, genetic and innate immune factors, including higher levels of type I interferons, as well as the induction of trained immunity and local mucosal immunity also contribute to lower risk of infection and amelioration of disease severity. The identification of immune correlates of protection will facilitate the development of effective vaccines and therapeutics strategies.

scholarly journals Reinfections in COVID-19 Patients: Impact of Virus Genetic Variability and Host Immunity

Vaccines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1168
Author(s):  
Aisha Fakhroo ◽  
Hebah A. AlKhatib ◽  
Asmaa A. Al Thani ◽  
Hadi M. Yassine
Keyword(s):  
Social Life ◽  
Protective Immunity ◽  
Host Factors ◽  
Severe Illness ◽  
Rapid Decline ◽  
Rapid Spread ◽  
Antibody Titers ◽  
Variant Lineage ◽  
Humoral Responses ◽  
Induced Immunity

The COVID-19 pandemic is still posing a devastating threat to social life and economics. Despite the modest decrease in the number of cases during September–November 2020, the number of active cases is on the rise again. This increase was associated with the emergence and spread of the new SARS-CoV-2 variants of concern (VOCs), such as the U.K. (B1.1.7), South Africa (B1.351), Brazil (P1), and Indian (B1.617.2) strains. The rapid spread of these new variants has raised concerns about the multiple waves of infections and the effectiveness of available vaccines. In this review, we discuss SARS-CoV-2 reinfection rates in previously infected and vaccinated individuals in relation to humoral responses. Overall, a limited number of reinfection cases have been reported worldwide, suggesting long protective immunity. Most reinfected patients were asymptomatic during the second episode of infection. Reinfection was attributed to several viral and/or host factors, including (i) underlying immunological comorbidities; (ii) low antibody titers due to the primary infection or vaccination; (iii) rapid decline in antibody response after infection or vaccination; and (iv) reinfection with a different SARS-CoV-2 variant/lineage. Infections after vaccination were also reported on several occasions, but mostly associated with mild or no symptoms. Overall, findings suggest that infection- and vaccine-induced immunity would protect from severe illness, with the vaccine being effective against most VOCs.

scholarly journals 116. Role of Maternal Antibodies in Protection Against Postnatal Cytomegalovirus Acquisition

2018 ◽  
Vol 5 (suppl_1) ◽  
pp. S4-S4
Author(s):  
Frances Saccoccio ◽  
Hannah Itell ◽  
Skukhang Li ◽  
Jennifer Jenks ◽  
Guan Xie ◽  
...  
Keyword(s):  
Vaccine Development ◽  
Natural Infection ◽  
The United States ◽  
Immune Correlates ◽  
Perinatal Hiv ◽  
Igg Binding ◽  
Maternal Hiv ◽  
Specific Igg ◽  
Humoral Responses

Abstract Background Congenital cytomegalovirus (CMV) is the leading infectious cause of birth defects in the United States. Development of an effective CMV vaccine is a public health priority. However, CMV vaccine development is limited by a poor understanding of the immune correlates of protection, including the role of CMV-specific IgG. Defining the role of passively acquired maternal IgG in the protection of half of the CMV-exposed, breastfeeding infants against postnatal CMV acquisition may inform CMV vaccine design Methods We analyzed CMV-specific humoral responses in 29 CMV-seropositive Ugandan mother–infant pairs. Seventeen mothers were HIV co-infected. Infants were followed weekly for postnatal CMV acquisition using saliva PCR. Twelve infants acquired CMV and 17 infants did not acquire CMV in the first 6 months of life. We compared CMV-specific IgG responses at delivery of mothers whose infants acquired CMV to mothers whose infants did not acquire CMV by 6 months of life and in the infants at 6 weeks of life. We also compared CMV-specific responses in mothers at delivery and infants at 6 weeks of life based on maternal HIV status. Results We found similar CMV-specific total IgG and IgG3 binding, avidity index, neutralization, antibody-dependent cellular phagocytosis, and antibody-dependent cellular cytotoxicity responses in mothers whose infants did or did not acquire CMV by 6 months of life. Moreover, similar CMV-specific IgG binding and neutralization responses were also found between infants who did or did not acquire CMV by 6 months of life. Finally, CMV-specific IgG responses were similar in HIV-infected and uninfected mothers at delivery and in infants at 6 weeks of life regardless of perinatal HIV exposure. Conclusion CMV-binding and functional IgG responses do not appear to impact infant susceptibility to postnatal CMV acquisition in the first 6 months of life, and therefore other viral or immunologic factors contribute to the inefficiency of this mode of CMV transmission. Thus, to provide sterilizing protection against mucosal CMV acquisition, an antibody-based CMV vaccine would likely have to induce higher magnitude or qualitatively different responses than that of natural infection. Disclosures All authors: No reported disclosures.

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