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Human adenoviruses (AdVs) have been extensively studied as vectors for gene therapy and vaccination. However, little attention has been paid to AdV vaccine development and treatment. Currently, there is a lack of information concerning the immunogenicity of AdV major capsid proteins. Here, using AdV7 as a model, we compared the immunogenicity and protection efficacy of its three major capsid proteins in DNA forms, pFiber, pHexon and pPenton, on a mouse model. Quantification of antigen-specific antibodies showed that pHexon induced highest IgG in sera while pPenton induced highest IgA in respiratory mucosae. A neutralization assay revealed that pPenton elicited the highest neutralizing activity against the homologous AdV7 in both sera and bronchoalveolar lavages (BALs). In addition, sera and BALs from mice immunized with either of the three constructs had cross-neutralizing activities against the heterologous AdV3. Furthermore, pHexon and pPenton induced Th1/2- and Th1/17-biased cellular responses, respectively, with pFiber being the weakest in the induction of cellular responses. Virus challenge assay showed that, pPenton group had the fastest virus clearance rate, followed by pFiber and pHexon groups. Likewise, the inflammation in the lung was well controlled in pPenton group against virus challenge. Taken together, our data demonstrate that penton base is better than fiber and hexon as a vaccine candidate against AdVs. Our findings provide important information for the development of subunit vaccines against AdVs.

Background Agonists of TLR3 and TLR4 are effective immunoadjuvants for different types of vaccines. The mechanisms of their immunostimulatory action differ significantly; these differences are particularly critical for immunization with non-replicating adenovirus vectors (rAds) based vaccines. Unlike traditional vaccines, rAd based vaccines are not designed to capture vaccine antigens from the external environment by antigen presenting cells (APCs), but rather they are targeted to the de novo synthesis of vaccine antigens in APCs transfected with rAd. To date, there is no clear understanding about approaches to improve the efficacy of rAd vaccinations with immunoadjuvants. In this study, we investigated the immunoadjuvant effect of TLR3 and TLR4 agonists on the level of activation of APCs during vaccination with rAds. Results We demonstrated that TLR3 and TLR4 agonists confer different effects on the molecular processes in APCs that determine the efficacy of antigen delivery and activation of antigen-specific CD4+ and CD8+ T cells. APCs activated with agonists of TLR4 were characterized by up-regulated production of target antigen mRNA and protein encoded in rAd, as well as enhanced expression of the co-activation receptors CD80, CD86 and CD40, and pro-inflammatory cytokines TNF-α, IL6 and IL12. These effects of TLR4 agonists have provided a significant increase in the number of antigen-specific CD4+ and CD8+ T cells. TLR3 agonist, on the contrary, inhibited transcription and synthesis of rAd-encoded antigens, but improved expression of CD40 and IFN-β in APCs. The cumulative effect of TLR3 agonist have resulted in only a slight improvement in the activation of antigen-specific T cells. Also, we demonstrated that IFN-β and TNF-α, secreted by APCs in response to TLR3 and TLR4 agonists, respectively, have an opposite effect on the transcription of the targeted gene encoded in rAd. Specifically, IFN-β inhibited, and TNF-α stimulated the expression of target vaccine antigens in APCs. Conclusions Our data demonstrate that agonists of TLR4 but not TLR3 merit further study as adjuvants for development of vaccines based on recombinant adenoviral vectors. Electronic supplementary material The online version of this article (10.1186/s12865-018-0264-x) contains supplementary material, which is available to authorized users.

Human adenovirus (Ad) species B contains several of the most important types associated with acute respiratory diseases, Ad3, -7, -14 and -55, which often lead to severe lower respiratory tract diseases and epidemic outbreaks. However, there is currently no Ad vaccine approved for general use. The major capsid protein, hexon, is the primary determinant recognized by neutralizing antibodies (NAbs). In this study, four recombinant Ads that have the same genome sequence as Ad3 with the exception of the hexon genes, rAd3EGFP, rAd3H7, rAd3H14 and rAd3H55, were combined as a tetravalent Ad candidate vaccine against Ad3, -7, -14 and -55. The replication efficiencies of chimeric rAd3H14, rAd3H7 and rAd3H55 were similar to that of rAd3EGFP. Recombinant rAd3EGFP, rAd3H7, rAd3H14 and rAd3H55 induced high titers of NAbs against Ad3, -7, -14 and -55, respectively, which were comparable to those induced by wild-type Ads. The mixture of the four recombinant Ads in equal proportions, rAdMix, or rAdMix inactivated by β-propiolactone, induced balanced NAb responses against Ad3, -7, -14 and -55 in mice without reciprocal immunological interference. In co-culture the four recombinant Ads replicated with a similar efficiency without reciprocal inhibition, and the progeny virions may be chimeric. Purified co-culture, rAdMix-C, also elicited balanced immune responses, suggesting a simple method for multivalent vaccine production. These results indicate the possible advantage of the four Ads as a live combined vaccine. Importantly, pre-immunization with rAdMix conferred protection against Ad3, -7, -14 or -55 challenge in mice in vivo. Thus, this research provides a novel tetravalent Ad vaccine candidate against Ad3, -7, -14 and -55.

Historically, fowl adenovirus (FAdV) associated inclusion body hepatitis (IBH) was considered a secondary disease in broiler chickens associated with immunosuppression. However, we previously reported the occurrence of IBH as a primary disease in the broiler chicken industry in Canada as a result of infections with various FAdV serotypes. Therefore, the objectives of this study were to develop an immunization strategy in broiler breeders using live FAdV 11-1047 and FAdV8a-TR59 to confer homologous and heterologous protection in broiler progeny against IBH and to study the efficacy of natural exposure of naive broiler breeders to a vaccine virus from live FAdV vaccinated birds as an immunization technique. Broiler breeders vaccinated orally with FAdV8a-TR59 (1 × 104 TCID50/bird) and FAdV11–1047 (1 × 104 TCID50/bird), FAdV8a-TR59 (1 × 106 TCID50/bird) and FAdV11-1047 (1 × 106 TCID50/bird) or FAdV8b (1 × 106 TCID50/bird) transferred substantial levels of neutralizing antibodies to their progeny. The efficacy of maternal antibodies was studied by challenging 14-day old broiler chickens with 1 × 107 TCID50 of FAdV2–685, FAdV7-x11a like, FAdV8a-TR59, FAdV8b-SK or FAdV11-1047 which are the dominant serotypes causing IBH outbreaks in Canada. Broiler chickens from the low and high dose vaccinated breeders were significantly protected against all serotypes of FAdV (P

Human adenoviruses types 3 (HAdV-3), 7 (HAdV-7) and 55 (HAdV-55) are major pathogens of acute respiratory infections (ARI) in children and adults. More than one type of HAdV can infect patients simultaneously, and the infections are sometimes fatal. However, there is currently no vaccine approved for general use in children and adults. Thus, development of a multivalent HAdV vaccine to combat HAdV infection becomes imperative. In this study, we constructed a new recombinant trivalent human adenovirus vaccine (rAdMHE3-h55), which expresses the hexon protein of HAdV-55 in the E3 region of rAdMHE3, a previously prepared bivalent vaccine candidate against HAdV-3 and HAdV-7. The results of in vitro neutralization assays indicate that rAdMHE3-h55 can induce the production of neutralizing antibodies against HAdV-3, HAdV-7, and HAdV-55 in mice. Furthermore, immunization with the recombinant trivalent vaccine candidate completely protected the mice challenged with HAdV-3, HAdV-7, orHAdV-55, respectively, showing lower lung viral loads and less lung Pathological changes was compared with those in unvaccinated mice. The current findings contribute to the development of a new adenovirus vaccine candidate and also advance this construction method for the generation of recombinant adenovirus vaccines. In conclusion, our recombinant trivalent vaccine rAdMHE3-h55 can provides protection against challenge with HAdV-3, HAdV-7, or HAdV-55 in mice. Future work of optimizing this vaccine candidate may lead to a more effective way of preventing respiratory diseases caused by common human adenoviruses.

The spread of hydropericardium syndrome has recently become serious in China since 2015. There is, therefore, an urgent need for new, safe and effective vaccines that prevent the disease. Here, the immune protection induced by Escherichia coli-expressed capsid proteins of fowl adenovirus serotype 4, including fiber-1, fiber-2, penton base and hexon (loop-1 region) were compared in chickens at different inoculation amounts. According to challenge mortalities and tissue gross/micro lesion results, fiber-2 induced the best protection, followed by fiber-1 and hexon. Fiber-1 and fiber-2 provided complete protection against 105.5 TCID50 viral load challenge with 100 or 50μg doses per chicken, respectively. Penton could induce effective protection only at the high dosage of 200μg per chicken. The immunoprotective characteristics of these FAdV-4 capsid proteins may prove useful for developing subunit vaccines to control hydropericardium syndrome.

Viral pathogens have evolved a wide range of tactics to evade host immune responses and thus propagate effectively. One efficient tactic is to divert host immune responses toward an immunodominant decoy epitope and to induce non-neutralizing antibodies toward this epitope. Therefore, it is expected that the amount of decoy epitope in a subunit vaccine can affect the level of neutralizing antibody in an immunized animal. In this study, we tested this hypothesis by generating an antibody specific to the decoy epitope on the capsid protein of porcine circovirus type 2 (PCV2). Using this antibody, we found that two commercial vaccines contained statistically different amounts of the decoy epitope. The vaccine with lower levels of decoy epitope induced a significantly higher level of neutralizing antibody after immunization. This antibody can be used as an analytical tool to monitor the quality of a vaccine from batch to batch., Highlights • We generated a novel antibody specific to an immunodominant decoy epitope of PCV2. • Using this novel antibody, we measured levels of decoy epitope in PCV2 vaccine. • Decoy epitope in PCV2 vaccine affected the neutralizing antibody titer induction.

Febrile respiratory illness resulting from adenovirus types 4 and 7 (Ad4/7) was endemic at military training camps, but controlled by an Ad4/7 vaccine from the 1970s to 1999, the year it was discontinued. Thereafter, rates returned to prevaccine levels. Rates dropped after reintroduction of an Ad4/7 vaccine in 2011.Surfaces of the barracks and medical clinic of a training camp were swabbed in 3 studies in 2004 and 1 study in 2007, and tested with culture and polymerase chain reaction (PCR). Similar swabbing was done in 2013 and 2015 and tested with PCR.In the studies before 2011 (prevaccine), 12% of samples were Ad4/7 positive by culture and 27% positive by PCR. In the 2 studies after 2011 (postvaccine), no samples were Ad4/7 positive.The Ad 4/7 vaccine has resulted in the near elimination of Ad4/7-related disease and the disappearance of Ad4/7 from surfaces in a military basic training camp. Renewed transmission of Ad4/7 in this setting would likely require new importation from military recruits and an immunologically naive cohort, which the current vaccination program prevents.

Porcine circovirus type 2 (PCV2) is the main pathogen of porcine circovirus associated disease (PCVAD), causing great economic losses in pig industry. In previous study, we constructed adenovirus vector vaccines expressing PCV2 Cap either modified with Intron A and WPRE, or CD40L and GMCSF, and evaluated all of these vaccines in mice and in pigs. Although Ad-A-C-W and Ad-CD40L-Cap-GMCSF could induce stronger immune responses than Ad-Cap, neither of them was better than commercial inactivated vaccine PCV2 SH-strain. In this study, secretory recombinant adenoviruses (Ad-A-spCap-W and Ad-A-spCD40L-spCap-spGMCSF-W) and non-secretory recombinant adenovirus Ad-A-CD40L-Cap-GMCSF-W were constructed, and identified by western blot and confocal laser microscope observation. The results of ELISA and VN showed that humoral immune responses induced by Ad-A-spCap-W and Ad-A-CD40L-Cap-GMCSF-W were not significantly different from SH-strain, but Ad-A-spCD40L-spCap-spGMCSF-W could induce significantly higher humoral immune response than SH-strain. Lymphocytes proliferative and cytokines releasing levels of Ad-A-spCap-W and Ad-A-CD40L-Cap-GMCSF-W were not significantly different from SH-strain, but Ad-A-spCD40L-spCap-spGMCSF-W was significantly higher than SH-strain. PCV2-challenge experiment showed that virus loads were significantly reduced in Ad-A-spCD40L-spCap-spGMCSF-W vaccinated group, and no obviously clinical and microscopic lesions were observed in Ad-A-spCD40L-spCap-spGMCSF-W vaccinated group. Altogether, these results demonstrate that recombinant adenovirus vaccine Ad-A-spCD40L-spCap-spGMCSF-W induces stronger immune responses and provides better protection than commercial inactivated vaccine PCV2 SH-strain, and suggest that Ad-A-spCD40L-spCap-spGMCSF-W could be a potential vaccine candidate against PCVAD.

Adenovirus (AdV)-based vectors are popular experimental vaccine vectors, but despite their ability to induce strong immune responses, their application is impeded by widespread preexisting immunity against many AdV types that can impair or even abrogate the induction of transgene-specific immune responses. Therefore, the development of vectors based on AdV types with a low seroprevalence is important for effective AdV-based immunization in humans. We investigated the immunization efficacy of vectors based on AdV type 48 (Ad48) and Ad50 in the ovalbumin (ova) model as well as the Friend retrovirus (FV) model, which allows testing of the protective effect of vaccine-induced immunity. Using ova-encoding vectors, we found a significantly lower induction of ova-specific CD8+ T cells and antibody responses by Ad48- and Ad50-based vectors than by Ad5-based vectors. Similarly, we found a reduced induction of FV-specific CD8+ T cell responses in Ad48- and Ad50.Leader-Gag-immunized mice compared with that in Ad5-immunized mice; however, some of those mice were able to control the FV infection, and protection correlated with the level of neutralizing antibodies 10 days after FV challenge. Analyses of the AdV-specific antibodies and CD8+ T cells induced by the individual AdV types revealed a high level of cross-reactivity, and the efficacy of Ad48-based immunization was impaired in Ad5-preimmune mice. Our results show that the immunity induced by Ad48- and Ad50-based vectors is reduced compared to that induced by Ad5 and is sufficient to control FV infection in only some of the immunized mice. A high level of cross-reactivity suggests that AdV preimmunity must be considered even when applying rare AdV-based vectors. IMPORTANCE AdV-based vectors are important tools for the development of vaccines against a wide range of pathogens. While AdV vectors are generally considered safe and highly effective, their application can be severely impaired by preexisting immunity due to the widespread seroprevalence of some AdV types. The characterization of different AdV types with regard to immunogenicity and efficacy in challenge models is of great importance for the development of improved AdV-based vectors that allow for efficient immunization despite anti-AdV immunity. We show that the immunity induced by an Ad48-based vector is inferior to that induced by an Ad5-based vector but can still mediate the control of an FV infection in highly FV-susceptible mice. However, the efficacy of Ad48-based immunization was impaired in Ad5-preimmune mice. Importantly, we found cross-reactivity of both the humoral and cellular immune responses raised by the individual AdV types, suggesting that switching to a different AdV type may not be sufficient to circumvent preexisting anti-AdV immunity.

Background A number of serious human adenovirus (HAdV) outbreaks have been recently reported: HAdV-B7 (Israel, Singapore, and USA), HAdV-B7d (USA and China), HAdV-D8, -D54, and -C2 (Japan), HAdV-B14p1 (USA, Europe, and China), and HAdV-B55 (China, Singapore, and France). Methods To understand the epidemiology of HAdV infections in Singapore, we studied 533 HAdV-positive clinical samples collected from 396 pediatric and 137 adult patients in Singapore from 2012 to 2018. Genome sequencing and phylogenetic analyses were performed to identify HAdV genotypes, clonal clusters, and recombinant or novel HAdVs. Results The most prevalent genotypes identified were HAdV-B3 (35.6%), HAdV-B7 (15.4%), and HAdV-E4 (15.2%). We detected 4 new HAdV-C strains and detected incursions with HAdV-B7 (odds ratio [OR], 14.6; 95% confidence interval [CI], 4.1–52.0) and HAdV-E4 (OR, 13.6; 95% CI, 3.9–46.7) among pediatric patients over time. In addition, immunocompromised patients (adjusted OR [aOR], 11.4; 95% CI, 3.8–34.8) and patients infected with HAdV-C2 (aOR, 8.5; 95% CI, 1.5–48.0), HAdV-B7 (aOR, 3.7; 95% CI, 1.2–10.9), or HAdV-E4 (aOR, 3.2; 95% CI, 1.1–8.9) were at increased risk for severe disease. Conclusions Singapore would benefit from more frequent studies of clinical HAdV genotypes to identify patients at risk for severe disease and help guide the use of new antiviral therapies, such as brincidofovir, and potential administration of HAdV 4 and 7 vaccine., Human adenovirus (HAdV) outbreaks are often inexplicable with sparse clinical epidemiological data. We sought to describe clinical HAdV genotypes and identify risk factors associated with severe disease among HAdV-positive patients seen at 2 hospitals in Singapore.

Human adenovirus type 26 uses sialic acid as a primary cellular receptor—structural insights for this phase 3 vaccine vector., Adenoviruses are clinically important agents. They cause respiratory distress, gastroenteritis, and epidemic keratoconjunctivitis. As non-enveloped, double-stranded DNA viruses, they are easily manipulated, making them popular vectors for therapeutic applications, including vaccines. Species D adenovirus type 26 (HAdV-D26) is both a cause of EKC and other diseases and a promising vaccine vector. HAdV-D26–derived vaccines are under investigation as protective platforms against HIV, Zika, and respiratory syncytial virus infections and are in phase 3 clinical trials for Ebola. We recently demonstrated that HAdV-D26 does not use CD46 or Desmoglein-2 as entry receptors, while the putative interaction with coxsackie and adenovirus receptor is low affinity and unlikely to represent the primary cell receptor. Here, we establish sialic acid as a primary entry receptor used by HAdV-D26. We demonstrate that removal of cell surface sialic acid inhibits HAdV-D26 infection, and provide a high-resolution crystal structure of HAdV-D26 fiber-knob in complex with sialic acid.

Immunotherapeutic strategies based on Epstein-Barr virus (EBV) latent membrane protein 2 (LMP2) antigen-specific cytotoxic T lymphocytes (CTLs) have been proven to boost LMP2-specific CTL responses in patients with nasopharyngeal carcinoma (NPC). Such strategies can produce clinical benefits in some patients with NPC. Currently, the major challenge limiting the use of immunotherapy for NPC is its low clinical response rate. The efficacy of immunotherapy based on EBV-LMP2 specific CTLs depends mainly on their cytotoxic activity, but no studies have been conducted to elucidate this activity. In this study, laser confocal scanning microscopy (LCSM) and real-time cell analysis (RTCA) were used to evaluate the killing function and its underlying mechanism of LMP2-specific CTLs. LCSM showed that LMP2-specific CTLs recognize and kill target cells expressing viral escape protein LMP2, and that the killing rate is related to the number of CTLs adhering to the target cells. LMP2-specific CTL-mediated cytotoxicity is rate limited by the time required for effective contact and recognition between CTLs and target cells. RTCA showed that the protective effect of LMP2-specific CTLs required an appropriate effector-to-target ratio, and that LMP2-specific CTLs could not eradicate residual target cells at a low effector-to-target ratio. Moreover, our results revealed that LMP2-specific CTL responses involve two independent but complementary mechanisms: the perforin/granzyme and Fas/FasL pathways. Therefore, we have elucidated, for the first time, the selective cytotoxicity and mechanism by which LMP2-specific CTLs induced by the rAd-LMP2 vaccine kill target cells and have explored the killing mode and several key parameters of killing mediated by LMP2-specific CTLs. Our study will contribute to the knowledge of vaccines targeting EBV-LMP2 and to the improvement of immunotherapeutic strategies.

The major immunogenic protein capsid (Cap) of porcine circovirus type 2 (PCV2) is critical to induce neutralizing antibodies and protective immune response against PCV2 infection. This study was conducted to investigate the immune response of recombinant adenovirus expressing PCV2b Cap and C-terminal domain of Yersinia pseudotuberculosis invasin (Cap-InvC) fusion protein in pigs. The recombinant adenovirus rAd-Cap-InvC, rAd-Cap and rAd were generated and used to immunize pigs. The phosphate-buffered saline was used as negative control. The specific antibodies levels in rAd-Cap-InvC and ZJ/C-strain vaccine groups were higher than that of rAd-Cap group (p < 0.05), and the neutralization antibody titer in rAd-Cap-InvC group was significantly higher than those of other groups during 21-42 days post-immunization (DPI). Moreover, lymphocyte proliferative level, interferon-γ and interleukin-13 levels in rAd-Cap-InvC group were increased compared to rAd-Cap group (p < 0.05). After virulent challenge, viruses were not detected from the blood samples in rAd-Cap-InvC and ZJ/C-strain vaccine groups after 49 DPI. And the respiratory symptom, rectal temperature, lung lesion and lymph node lesion were minimal and similar in the ZJ/C-strain and rAd-Cap-InVC groups. In conclusion, our results demonstrated that rAd-Cap-InvC was more efficiently to stimulate the production of antibody and protect pigs from PCV2 infection. We inferred that InvC is a good candidate gene for further development and application of PCV2 genetic engineering vaccine.

Since the 1970s, replication-competent human adenoviruses 4 and 7 have been used as oral vaccines to protect U.S. soldiers against the severe respiratory diseases caused by these viruses. These vaccines are thought to establish a digestive tract infection conferring protection against respiratory challenge through antibodies. The success of these vaccines makes replication-competent adenoviruses attractive candidates for use as oral vaccine vectors. However, the inability of human adenoviruses to replicate efficiently in laboratory animals has hampered the study of such vectors. Here, we used mouse adenovirus type 1 (MAV-1) in mice to study oral replication-competent adenovirus-based vaccines. We show that MAV-1 oral administration provides protection that recapitulates the protection against homologous respiratory challenge observed with adenovirus 4 and 7 vaccines. Moreover, live oral MAV-1 vaccine better protected against a respiratory challenge than inactivated vaccines. This protection was linked not only with the presence of MAV-1-specific antibodies but also with a better recruitment of effector CD8 T cells. However, unexpectedly, we found that such oral replication-competent vaccine systemically spread all over the body. Our results therefore support the use of MAV-1 to study replication-competent oral adenovirus-based vaccines but also highlight the fact that those vaccines can disseminate widely in the body. IMPORTANCE Replication-competent adenoviruses appear to be promising vectors for the development of oral vaccines in humans. However, the study and development of these vaccines suffer from the lack of any reliable animal model. In this study, mouse adenovirus type 1 was used to develop a small-animal model for oral replication-competent adenovirus vaccines. While this model reproduced in mice what is observed with human adenovirus oral vaccines, it also highlighted that oral immunization with such a replication-competent vaccine is associated with the systemic spread of the virus. This study is therefore of major importance for the future development of such vaccine platforms and their use in large human populations.

CD8+ T lymphocytes play an important role in controlling infections by intracellular pathogens. Chemokines and their receptors are crucial for the migration of CD8+ T-lymphocytes, which are the main IFNγ producers and cytotoxic effectors cells. Although the participation of chemokine ligands and receptors has been largely explored in viral infection, much less is known in infection by Trypanosoma cruzi, the causative agent of Chagas disease. After T. cruzi infection, CXCR3 chemokine receptor is highly expressed on the surface of CD8+ T-lymphocytes. Here, we hypothesized that CXCR3 is a key molecule for migration of parasite-specific CD8+ T-cells towards infected tissues, where they may play their effector activities. Using a model of induction of resistance to highly susceptible A/Sn mice using an ASP2-carrying DNA/adenovirus prime-boost strategy, we showed that CXCR3 expression was upregulated on CD8+ T-cells, which selectively migrated towards its ligands CXCL9 and CXCL10. Anti-CXCR3 administration reversed the vaccine-induced resistance to T. cruzi infection in a way associated with hampered cytotoxic activity and increased proapoptotic markers on the H2KK-restricted TEWETGQI-specific CD8+ T-cells. Furthermore, CXCR3 receptor critically guided TEWETGQI-specific effector CD8+ T-cells to the infected heart tissue that express CXCL9 and CXCL10. Overall, our study pointed CXCR3 and its ligands as key molecules to drive T. cruzi-specific effector CD8+ T-cells into the infected heart tissue. The unveiling of the process driving cell migration and colonization of infected tissues by pathogen-specific effector T-cells is a crucial requirement to the development of vaccine strategies., Author summary Chemokine receptors and cell adhesion molecules are essential for T lymphocytes migration into infected tissues. Previously, our group demonstrated that CXCR3 receptor was highly expressed on specific CD8+ T-cells surface after immunization and infection by T. cruzi. Also, recirculation of specific CD8+ T-cells was more important than proliferation to control the infection by T cruzi. As CD8+ T lymphocytes are responsible for controlling T. cruzi infection by releasing IFN-γ or by direct cytotoxicity against infected target cells, our aim was to analyze the role of the chemokine receptor CXCR3 in the migration of specific CD8+ T-cells towards infected tissues. Our results revealed that intervention on CXCR3 by administration of a blocking anti-CXCR3 antibody decreased CD8+ T-cell migration, hampering the access of parasite-specific effector cell into the heart tissue of mice infected by T. cruzi. Therefore, to induce the appropriate migration footmarks is crucial for drive the pathogen-specific effector to sites of infection and, therefore, to clarify this requirement is a crucial strategy for vaccine development.

Vaccination offers the most cost-effective approach to limiting the adverse impact of infectious and neoplastic diseases that reduce the quality of life in sub-Saharan Africa (SSA). However, it is unclear what vaccine vectors would be most readily implementable in the setting and at what age they should be applied for maximal efficacy. Adenoviruses (Ad) and Ad-based vectors have been demonstrated to induce effective humoral and cellular immune responses in animal models and in humans. However, because immunity associated with Ad infection is lifelong, there exists a debate as to whether pre-existing immunity might decrease the efficacy of Ad vectored vaccines. In order to begin to rationally develop vaccination strategies for SSA, we have quantified neutralizing antibodies (nAb) against Ad4, Ad5, Ad7, Ad26, Ad28, Ad45 and Ad48 in 67 adult women and their infants. We are the first to define the decay kinetics of transferred maternal nAb in infants as well as the apparent initiation of de novo Ad responses. Our findings demonstrate that in Zambian adults, robust nAb responses exist against each of the Ads tested and are efficiently transferred to newborns. With few exceptions, neither the HIV-1 infection status of the mothers or the antiretroviral therapy (ART) treatment of HIV-1 disease had significant impact on maternal Ad nAb responses or their transfer to infants. However, maternal Ad nAb decays in infants to a nadir at 12 months of age such that any of the seven Ad types could function as vaccine vectors. The definition of this ‘window of opportunity’ provides important foundational data for rational design and implementation of Ad vectors in this setting.

Host immune responses play an important role in the outcome of infection with hepatitis C virus (HCV). They can lead to viral clearance and a positive outcome, or progression and severity of chronic disease. Extensive research in the past &gt, 25 years into understanding the immune responses against HCV have still resulted in many unanswered questions implicating a role for unknown factors and events. In our earlier studies, we made a surprising discovery that peptides derived from structural and non-structural proteins of HCV have substantial amino acid sequence homologies with various proteins of adenoviruses and that immunizing mice with a non-replicating, non-recombinant adenovirus vector leads to induction of a robust cross-reactive cellular and humoral response against various HCV antigens. In this work, we further demonstrate antibody cross-reactivity between Ad and HCV in vivo. We also extend this observation to show that recombinant adenoviruses containing antigens from unrelated pathogens also possess the ability to induce cross-reactive immune responses against HCV antigens along with the induction of transgene antigen-specific immunity. This cross-reactive immunity can (a) accommodate the making of dual-pathogen vaccines, (b) play an important role in the natural course of HCV infection and (c) provide a plausible answer to many unexplained questions regarding immunity to HCV.

Certain strains of fowl adenovirus serotype 4 (FAdV-4) of the family Adenoviridae are recognized to be the causative agents of Hydropericardium Syndrome (HPS) in broiler chicken. Despite the significantly spiking mortality in broilers due to HPS, not much effort has been made to design an effective vaccine against FAdV-4. The combination of immuno- and bioinformatics tools for immunogenic epitope prediction is the most recent concept of vaccine design. It reduces the time and effort required for hunting a potent vaccine candidate and is economical. Previously, we have reported the penton base protein of FAdV-4 to be a candidate for subunit vaccine against HPS. In the present study, we have computationally pre-screened promising B- and T-cell epitopes of the penton base. Multiple methods were employed for linear B-cell epitope identification; BepiPred and five other methods based on physicochemical properties of the amino acids. The penton base was homology modeled by means of Modeller 9.17 and after refinement of the model (by GalaxyRefine web server) ElliPro web tool was used to predict the discontinuous epitopes. NetMHCcons 1.1 and NetMHCIIpan 3.1 servers were used for the likelihood of peptide binding to Major Histocompatibility Complex (MHC) class I & II molecules respectively for T-cell epitope forecast. As a result, we identified the peptide stretch of 1–225 as the most promiscuous B- and T-cell epitope region in penton base Full Length (FL) protein sequence. Escherichia coli based expression vectors were generated containing cloned peptide stretch 1–225 (penton base1–225) and penton base FL gene sequence. The recombinant penton base1–225 and penton base FL proteins were expressed and purified using Escherichia coli-based expression system. Purification yield of penton base1–225 was 3-fold higher compared to penton base FL. These proteins were injected in chickens to determine their competence in protection against HPS. The results showed equal protection level of the two proteins and the commercial inactivated vaccine against FAdV-4 infection. The results suggest the peptide stretch 1–225 of penton base as a valuable candidate for developing an epitope-driven vaccine to combat HPS.

Aeromonas salmonicida, the oldest known fish pathogen and currently endemic throughout most of the world in both fresh and marine waters, causes severe economic losses to the salmon farming industry. Although there have been many studies on the prevention of furunculosis over the past few decades, it is still prevalent in many fisheries. In this study, a recombinant adenovirus vaccine candidate harboring the highly immunogenic Vapa gene (pAd-easy-cmv-Vapa) was successfully constructed and tested. The immune protection rate and specific antibody levels in the peripheral blood were then determined after immunizing rainbow trout. In addition, relative levels of IgM and IgT in the head kidney and hindgut before and after immunization were measured by quantitative reverse transcription PCR. Western blotting results indicated that the recombinant adenovirus could infect HEK-293 cells and express the A layer protein (encoded by Vapa). Further, survival analysis of fish 28 days after challenge showed that immunization significantly lowered the mortality rate (40%) compared to that in the control group (76.6%) and empty vector group (73.6%). This also led to an increase in specific antibodies in peripheral serum. In addition, levels of IgM and IgT in the head kidney and hindgut were increased to varying degrees. In conclusion, our research provides a candidate vaccine for the prevention of Aeromonas salmonicida A450 infection in rainbow trout and lays the foundation for future research on adaptive immune mechanisms associated with rainbow trout antibodies.

Two enveloped viral vectors, vesicular stomatitis virus and influenza virus, and a non-enveloped viral vector, human adenovirus type 5, were encapsulated by spray drying to enhance thermal stability. Results with these candidates led to the hypothesis that stability performance of chosen excipients may be less virus-specific, as previously postulated in the literature, and more differentiated based on whether the virus has a lipid envelope. Spray dried samples were characterized for their thermal properties, RNA viability and in vitro viral activity after storage at 37 °C for up to 30 days or at 45 °C for up to 3 days. The enveloped viral vectors, as a group, were more thermally stable in trehalose while the non-enveloped viral vector showed higher activity with mannitol as the primary excipient in blends. Trehalose shows strong hydrogen bonds with the envelope’s lipid membrane than the other carbohydrates, more effectively replacing water molecules while maintaining the fluidity of the membrane. Conversely, the small size of mannitol molecules was attributed to the more effective hydrogen bonding between water and the protein capsid of non-enveloped viral vectors. In all cases, a matrix with high glass transition temperature contributed to thermal stabilization through vitrification. This work suggests that carbohydrate stabilizer selection may be more dependent on the envelope rather than the specific viral vector, which, if universally true, will provide a guideline for future formulation development.

International audience; Introduction: Human adenovirus (HAdV)-derived vectors have been used in numerous pre-clinical and clinical trials during the last 40 years. Current research in HAdV-based vaccines focuses on improving transgene immunogenicity and safety. Because pre-existing humoral immunity against HAdV types correlate with reduced vaccine efficacy and safety, many groups are exploring the development of HAdV types vectors with lower seroprevalence. However, global seroepidemiological data are incomplete. Areas covered: The goal of this review is to centralize 65 years of research on (primarily) HAdV epidemiology. After briefly addressing adenovirus biology, we chronical HAdV seroprevalence studies and highlight major milestones. Finally, we analyze data from about 50 studies with respect to HAdVs types that are currently used in the clinic, or are in the developmental pipeline. Expert opinion: Vaccination is among the most efficient tools to prevent infectious disease. HAdV-based vaccines have undeniable potential, but optimization is needed and antivector immunity remains a challenge if the same vectors are to be administrated to different populations. Here, we identify gaps in our knowledge and the need for updated worldwide epidemiological data.

A respiratory outbreak associated with human adenovirus type 7 (HAdV-7) occurred among unvaccinated officer candidates attending initial military training. Respiratory infections associated with HAdV-7 can be severe, resulting in significant morbidity. Genomic sequencing revealed HAdV-7d, a genome type recently remerging in the United States as a significant respiratory pathogen, following reports from Southeast Asia. Twenty-nine outbreak cases were identified; this likely represents an underestimate. Although the HAdV type 4 and 7 vaccine is currently given to US military enlisted recruit trainees, it is not routinely given to officer candidates. Administration of the HAdV type 4 and 7 vaccine may benefit this cohort.

BackgroundFor the purpose of studying functional human dendritic cells (DCs) in a humanized mouse model that mimics the human immune system (HIS), a model referred to as HIS mice was established.MethodsHuman immune system mice were made by engrafting NOD/SCID/IL2Rgammanull (NSG) mice with human hematopoietic stem cells (HSCs) following the transduction of genes encoding human cytokines and human leukocyte antigen (HLA)-A2.1 by adeno-associated virus serotype 9 (AAV9) vectors.ResultsOur results indicate that human DC subsets, such as CD141+CD11c+ and CD1c+CD11c+ myeloid DCs, distribute throughout several organs in HIS mice including blood, bone marrow, spleen, and draining lymph nodes. The CD141+CD11c+ and CD1c+CD11c+ human DCs isolated from HIS mice immunized with adenoviruses expressing malaria/human immunodeficiency virus (HIV) epitopes were able to induce the proliferation of malaria/HIV epitopes-specific human CD8+ T cells in vitro. Upregulation of CD1c was also observed in human CD141+ DCs 1 day after immunization with the adenovirus-based vaccines.ConclusionsEstablishment of such a humanized mouse model that mounts functional human DCs enables preclinical assessment of the immunogenicity of human vaccines in vivo.

Covid-19 Vaccines and Pregnancy — A Conversation with CDC Director Rochelle Walensky In this audio interview conducted on April 16, 2021, the editors are joined by CDC director and infectious disea...