The genetic adjuvant IL-12 enhances the protective efficacy of a DNA vaccine for Venezuelan equine encephalitis virus delivered by intramuscular injection in mice

Intranasal delivery of an adenovirus-vector vaccine co-expressing a modified spike protein and a genetic adjuvant confers lasting mucosal immunity against SARS-CoV-2

The ongoing COVID-19 pandemic caused by SARS-CoV-2 infection has threatened global health. Since the first case of infection was reported in December 2019, SARS-CoV-2 has rapidly spread worldwide and caused millions of deaths. As vaccination is the best way to protect the host from invading pathogens, several vaccines have been developed to prevent the infection of SARS-CoV-2, saving numerous lives thus far. However, SARS-CoV-2 constantly changes its antigens, resulting in escape from vaccine-induced protection, and the longevity of immunity induced by vaccines remains an issue. Additionally, traditional intramuscular COVID-19 vaccines are insufficient at evoking mucosal-specific immune responses. Because the respiratory tract is the primary route of SARS-CoV-2 entry, the need for mucosal vaccines is strong. Using an adenoviral (Ad) vector platform, we generated Ad5-S.Mod, a recombinant COVID-19 vaccine that encodes modified-spike (S) antigen and the genetic adjuvant human CXCL9. Intranasal delivery of Ad5-S.Mod elicited superior airway humoral and T-cell responses over traditional intramuscular vaccines and protected mice from lethal SARS-CoV-2 infection. cDC1 cells were required for the generation of antigen-specific CD8⁺ T-cell responses and CD8⁺ tissue-resident memory T-cell development in intranasal Ad5-S.Mod vaccinated mice. Furthermore, we confirmed the efficacy of the intranasal Ad5-S.Mod vaccine in terms of transcriptional changes and identified lung macrophages as a key supporter of maintenance of lung-resident memory T and B cells. Our study demonstrates Ad5-S.Mod has the potential to confer protective immunity against SARS-CoV-2 and that lung macrophages support the maintenance of vaccine-induced tissue-resident memory lymphocytes.

A Historical Review of Military Medical Strategies for Fighting Infectious Diseases: From Battlefields to Global Health

The environmental conditions generated by war and characterized by poverty, undernutrition, stress, difficult access to safe water and food as well as lack of environmental and personal hygiene favor the spread of many infectious diseases. Epidemic typhus, plague, malaria, cholera, typhoid fever, hepatitis, tetanus, and smallpox have nearly constantly accompanied wars, frequently deeply conditioning the outcome of battles/wars more than weapons and military strategy. At the end of the nineteenth century, with the birth of bacteriology, military medical researchers in Germany, the United Kingdom, and France were active in discovering the etiological agents of some diseases and in developing preventive vaccines. Emil von Behring, Ronald Ross and Charles Laveran, who were or served as military physicians, won the first, the second, and the seventh Nobel Prize for Physiology or Medicine for discovering passive anti-diphtheria/tetanus immunotherapy and for identifying mosquito Anopheline as a malaria vector and plasmodium as its etiological agent, respectively. Meanwhile, Major Walter Reed in the United States of America discovered the mosquito vector of yellow fever, thus paving the way for its prevention by vector control. In this work, the military relevance of some vaccine-preventable and non-vaccine-preventable infectious diseases, as well as of biological weapons, and the military contributions to their control will be described. Currently, the civil-military medical collaboration is getting closer and becoming interdependent, from research and development for the prevention of infectious diseases to disasters and emergencies management, as recently demonstrated in Ebola and Zika outbreaks and the COVID-19 pandemic, even with the high biocontainment aeromedical evacuation, in a sort of global health diplomacy.

A DNA vaccine targeting VEE virus delivered by needle-free jet-injection protects macaques against aerosol challenge

We have previously shown that DNA vaccines expressing codon optimized alphavirus envelope glycoprotein genes protect both mice and nonhuman primates from viral challenge when delivered by particle-mediated epidermal delivery (PMED) or intramuscular (IM) electroporation (EP). Another technology with fewer logistical drawbacks is disposable syringe jet injection (DSJI) devices developed by PharmaJet, Inc. These needle-free jet injection systems are spring-powered and capable of delivering vaccines either IM or into the dermis (ID). Here, we evaluated the immunogenicity of our Venezuelan equine encephalitis virus (VEEV) DNA vaccine delivered by either the IM- or ID-DSJI devices in nonhuman primates. The protective efficacy was assessed following aerosol challenge. We found that a prime and single boost by either the IM or ID route resulted in humoral and cellular immune responses that provided significant protection against disease and viremia. Although the ID route utilized one-fifth the DNA dose used in the IM route of vaccination, and the measured humoral and cellular immune responses trended lower, the level of protection was high and performed as well as the IM route for several clinical endpoints.

Vaccine Advances against Venezuelan, Eastern, and Western Equine Encephalitis Viruses

Vaccinations are a crucial intervention in combating infectious diseases. The three neurotropic Alphaviruses, Eastern (EEEV), Venezuelan (VEEV), and Western (WEEV) equine encephalitis viruses, are pathogens of interest for animal health, public health, and biological defense. In both equines and humans, these viruses can cause febrile illness that may progress to encephalitis. Currently, there are no licensed treatments or vaccines available for these viruses in humans. Experimental vaccines have shown variable efficacy and may cause severe adverse effects. Here, we outline recent strategies used to generate vaccines against EEEV, VEEV, and WEEV with an emphasis on virus-vectored and plasmid DNA delivery. Despite candidate vaccines protecting against one of the three viruses, few studies have demonstrated an effective trivalent vaccine. We evaluated the potential of published vaccines to generate cross-reactive protective responses by comparing DNA vaccine sequences to a set of EEEV, VEEV, and WEEV genomes and determining the vaccine coverages of potential epitopes. Finally, we discuss future directions in the development of vaccines to combat EEEV, VEEV, and WEEV.

Nanoplasmid Vectors Co-expressing Innate Immune Agonists Enhance DNA Vaccines for Venezuelan Equine Encephalitis Virus and Ebola Virus

DNA vaccines expressing codon-optimized Venezuelan equine encephalitis virus (VEEV) and Ebola virus (EBOV) glycoprotein genes provide protective immunity to mice and nonhuman primates when delivered by intramuscular (IM) electroporation (EP). To achieve equivalent protective efficacy in the absence of EP, we evaluated VEEV and EBOV DNA vaccines constructed using minimalized Nanoplasmid expression vectors that are smaller than conventional plasmids used for DNA vaccination. These vectors may also be designed to co-express type I interferon inducing innate immune agonist genes that have an adjuvant effect. Nanoplasmid vaccinated mice had increased antibody responses as compared to those receiving our conventional pWRG7077-based vaccines when delivered by IM injection, and these responses were further enhanced by the inclusion of the innate immune agonist genes. The Nanoplasmid VEEV DNA vaccines also significantly increased protection against aerosol VEEV challenge as compared to the pWRG7077 VEEV DNA vaccine. Although all mice receiving the pWRG7077 and Nanoplasmid EBOV DNA vaccines at the dose tested survived EBOV challenge, only mice receiving the Nanoplasmid EBOV DNA vaccine that co-expresses the innate immune agonist genes failed to lose weight after challenge. Our results suggest that Nanoplasmid vectors can improve the immunogenicity and protective efficacy of alphavirus and filovirus DNA vaccines.

GP38-targeting monoclonal antibodies protect adult mice against lethal Crimean-Congo hemorrhagic fever virus infection

Crimean-Congo hemorrhagic fever virus (CCHFV) is an important human pathogen. Limited evidence suggests that antibodies can protect humans against lethal CCHFV disease but the protective efficacy of antibodies has never been evaluated in adult animal models. Here, we used adult mice to investigate the protection provided against CCHFV infection by glycoprotein-targeting neutralizing and non-neutralizing monoclonal antibodies (mAbs). We identified a single non-neutralizing antibody (mAb-13G8) that protected adult type I interferon-deficient mice >90% when treatment was initiated before virus exposure and >60% when administered after virus exposure. Neutralizing antibodies known to protect neonatal mice from lethal CCHFV infection failed to confer protection regardless of immunoglobulin G subclass. The target of mAb-13G8 was identified as GP38, one of multiple proteolytically cleaved glycoproteins derived from the CCHFV glycoprotein precursor polyprotein. This study reveals GP38 as an important antibody target for limiting CCHFV pathogenesis and lays the foundation to develop immunotherapeutics against CCHFV in humans.

Effect of miR-155 as a molecular adjuvant of DNA vaccine against VHSV in olive flounder (Paralichthys olivaceus)

Rhabdoviral G protein-based DNA vaccines have been recognized as a useful way to protect cultured fish from rhabdoviral diseases. In Korea, viral hemorrhagic septicemia virus (VHSV) genotype IVa has been the primary culprit of high mortalities of cultured olive flounder (Paralichthys olivaceus). In this study, we inserted a miR-155-expressing cassette into the VHSV's G protein-based DNA vaccine, and analyzed the effects of miR-155 on the antiviral activity and on the vaccine efficacy in olive flounder. Olive flounder fingerlings were intramuscularly (i.m.) immunized with 10 μg/fish (1st experiment) or 1 μg/fish (2nd experiment) of DNA vaccine plasmids. However, there were no significant differences in mortalities and serum neutralization titers between fish immunized with 1 μg and 10 μg plasmids/fish, suggesting that i.m. injection with 1 μg plasmids/fish would be enough to induce effective adaptive immune responses in olive flounder fingerlings. In survival rates, as fish immunized with just G protein expressing plasmids showed no or too low mortalities, the adjuvant effect of miR-155 was not discernible. Also, in the serum neutralization activities, although G gene or G gene plus miR-155 expressing DNA vaccines induced significantly higher activities than control vaccines (PBS and vacant vector), no significant differences were found between G gene alone and G gene plus miR-155 expressing DNA vaccines. In the serum virucidal activity, fish immunized with G gene plus miR-155 expressing DNA vaccine showed significantly higher activity against hirame rhabdovirus (HIRRV) at 3 days post-immunization (d.p.i.) compared to other groups, suggesting that miR-155 produced from the vector can enhance innate immune responses in olive flounder. The significantly enhanced serum virucidal activities against VHSV especially at 28 d.p.i. in the groups immunized with G gene alone and G gene plus miR-155 expressing DNA vaccines reflect the increased antibodies against G protein, which could activate the classical complement pathway and subsequent viral inactivation. As the available information on the DNA vaccines in olive flounder is not sufficient, more diverse researches on the protective efficacy of DNA vaccines are needed to make more practical use of DNA vaccines in olive flounder farms.