Innate immunity: impact on the adaptive immune response

Plasmid DNAs expressing influenza virus hemagglutinin glycoproteins have been tested for their ability to raise protective immunity against lethal influenza challenges of the same subtype. In trials using two inoculations of from 50 to 300 micrograms of purified DNA in saline, 67-95% of test mice and 25-63% of test chickens have been protected against a lethal influenza challenge. Parenteral routes of inoculation that achieved good protection included intramuscular and intravenous injections. Successful mucosal routes of vaccination included DNA drops administered to the nares or trachea. By far the most efficient DNA immunizations were achieved by using a gene gun to deliver DNA-coated gold beads to the epidermis. In mice, 95% protection was achieved by two immunizations with beads loaded with as little as 0.4 micrograms of DNA. The breadth of routes supporting successful DNA immunizations, coupled with the very small amounts of DNA required for gene-gun immunizations, highlight the potential of this remarkably simple technique for the development of subunit vaccines.

https://www.pnas.org/content/pnas/90/24/11478.full.pdf

DNA vaccines: protective immunizations by parenteral, mucosal, and gene-gun inoculations

The development and widespread use of vaccines against infectious agents have been a great triumph of medical science. One reason for the success of currently available vaccines is that they are capable of inducing long-lived antibody responses, which are the principal agents of immune protection against most viruses and bacteria. Despite these successes, vaccination against intracellular organisms that require cell-mediated immunity, such as the agents of tuberculosis, malaria, leishmaniasis, and human immunodeficiency virus infection, are either not available or not uniformly effective. Owing to the substantial morbidity and mortality associated with these diseases worldwide, an understanding of the mechanisms involved in generating long-lived cellular immune responses has tremendous practical importance. For these reasons, a new form of vaccination, using DNA that contains the gene for the antigen of interest, is under intensive investigation, because it can engender both humoral and cellular immune re...

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DNA vaccines: immunology, application, and optimization*.

A method for delivering an isolated polynucleotide such as DNA or RNA, to the interior of a cell in a mammal comprising the injection of an isolated polynucleotide into a muscle of the mammal where the polynucleotide is taken up by the cells of the muscle and exerts a therapeutic effect on the mammal. The method can be used to deliver a therapeutic polypeptide to the cells of the mammal, to provide an immune response upon in vivo translation of the polynucleotide, to deliver antisense polynucleotides, to deliver receptors to the cells of the mammal or to provide transitory gene therapy.

Induction of a protective immune response in a mammal by injecting a DNA sequence

Vaccination with naked DNA elicits cellular and humoral immune responses that have a T helper cell type 1 bias. However, plasmid vectors expressing large amounts of gene product do not necessarily induce immune responses to the encoded antigens. Instead, the immunogenicity of plasmid DNA (pDNA) requires short immunostimulatory DNA sequences (ISS) that contain a CpG dinucleotide in a particular base context. Human monocytes transfected with pDNA or double-stranded oligonucleotides containing the ISS, but not those transfected with ISS-deficient pDNA or oligonucleotides, transcribed large amounts of interferon-α, interferon-β, and interleukin-12. Although ISS are necessary for gene vaccination, they down-regulate gene expression and thus may interfere with gene replacement therapy by inducing proinflammatory cytokines.

http://science.sciencemag.org/content/sci/273/5273/352.full.pdf

Immunostimulatory DNA Sequences Necessary for Effective Intradermal Gene Immunization

Cytotoxic T lymphocytes (CTLs) specific for conserved viral antigens can respond to different strains of virus, in contrast to antibodies, which are generally strain-specific. The generation of such CTLs in vivo usually requires endogenous expression of the antigen, as occurs in the case of virus infection. To generate a viral antigen for presentation to the immune system without the limitations of direct peptide delivery or viral vectors, plasmid DNA encoding influenza A nucleoprotein was injected into the quadriceps of BALB/c mice. This resulted in the generation of nucleoprotein-specific CTLs and protection from a subsequent challenge with a heterologous strain of influenza A virus, as measured by decreased viral lung titers, inhibition of mass loss, and increased survival.

https://science.sciencemag.org/content/sci/259/5102/1745.full.pdf

Heterologous protection against influenza by injection of DNA encoding a viral protein

Cytotoxic T lymphocytes (CTLs) expressing the CD8 surface marker recognize peptides in association with major histocompatibility complex (MHC) class I molecules. Although most peptides expressed on MHC class I molecules are derived from self- or virally encoded proteins, delivery of exogenous proteins to the cytosol can result in their being processed for presentation to CTLs on MHC class I molecules. We describe two fusion proteins (PEMa and PENP), consisting of the binding and translocating domains of Pseudomonas exotoxin A (PE), fused to peptide epitopes from influenza A matrix protein and nucleoprotein, respectively. These fusion proteins were internalized and processed by MHC class I-positive target cells, resulting in sensitization of target cells for lysis by peptide-specific CTLs. A point mutation known to interfere with intoxication by wild-type PE also reduced the ability of PEMa to sensitize target cells. Fusion of peptide or polypeptide epitopes with PE provides a potential means of eliciting CTLs without the use of self-replicating agents, as well as a useful probe for studying MHC class I-restricted antigen processing.

Targeted delivery of peptide epitopes to class I major histocompatibility molecules by a modified Pseudomonas exotoxin.

Protein carriers vary in their ability to increase the immunogenicity of poorly immunogenic or T-lymphocyte-independent antigens. We examined one such carrier, the outer membrane protein complex derived from Neisseria meningitidis serogroup B strain B11, in an attempt to determine why this outer membrane protein complex was more immunogenic in young infants and in relevant animal models than two other carriers used in conjugates made with Haemophilus influenzae type b polysaccharide, a T-cell-independent antigen. A single protein of the outer membrane protein complex, the class 2 porin protein, was purified and shown to function as a T-helper lymphocyte carrier protein. Unexpectedly, it was also found to have mitogenic activity for lymphocytes that was not due to lipopolysaccharide. This mitogenic activity appears to date to be unique to this carrier protein of the carrier proteins tested and may contribute to the ability of the H. influenzae type b conjugate vaccine made with the outer membrane protein complex to generate IgG anti-polysaccharide antibody responses in mice and infant monkeys and protective immune responses in infants less than 6 months of age.

https://www.pnas.org/content/pnas/89/10/4633.full.pdf

A vaccine carrier derived from Neisseria meningitidis with mitogenic activity for lymphocytes.

Recombinant DNA sequences coding for hybrid proteins having two primary components. The first component is a modified bacterial toxin that has translocating ability, while the second component is a polypeptide or protein that is exogenous to an antigen-presenting cell. The hybrid has the ability to be internalized by an antigen-presenting cell, where the hybrid is subsequently processed and an antigenic segment of the hybrid presented on the surface of the antigen-presenting cell, where the segment elicits an immune response by cytotoxic T lymphocytes.

Linda A. Hawe

Papers

Heterologous protection against influenza by injection of DNA encoding a viral protein

Targeted delivery of peptide epitopes to class I major histocompatibility molecules by a modified Pseudomonas exotoxin.

A vaccine carrier derived from Neisseria meningitidis with mitogenic activity for lymphocytes.

Recombinant DNA sequences and plasmids for cellular immunity vaccines from bacterial toxinantigen conjugates