Accelerated and intensified manufacturing of an adenovirus-vectored vaccine to enable rapid outbreak response.

The Coalition for Epidemic Preparedness Innovations' "100-day moonshot" aspires to launch a new vaccine within 100 days of pathogen identification, followed by large-scale vaccine availability within the "second hundred days." Here, we describe work to optimize adenoviral vector manufacturing for rapid response, by minimizing time to clinical trial and first large-scale supply, and maximizing output from the available manufacturing footprint. We describe a rapid virus seed expansion workflow that allows vaccine release to clinical trials within 60 days of antigen sequence identification, followed by vaccine release from globally distributed sites within a further 40 days. We also describe a perfusion-based upstream production process, designed to maximize output while retaining simplicity and suitability for existing manufacturing facilities. This improves upstream volumetric productivity of ChAdOx1 nCoV-19 by approximately fourfold and remains compatible with the existing downstream process, yielding drug substance sufficient for 10,000 doses from each liter of bioreactor capacity. This accelerated manufacturing process, along with other advantages such as thermal stability, supports the ongoing value of adenovirus-vectored vaccines as a rapidly adaptable and deployable platform for emergency response.

Spray vaccination with a Newcastle disease virus (NDV)-vectored infectious laryngotracheitis (ILT) vaccine protects commercial chickens from ILT in the presence of maternally-derived antibodies.

Infectious laryngotracheitis (ILT) poses a significant threat to the poultry industry, and vaccines play an important role in protection. However, due to the increasing scale of poultry production, there is an urgent need to develop vaccines that are suitable for convenient immunization methods such as spraying. Previous studies have shown that Newcastle disease virus (NDV)-ILT vaccines administered via intranasal and intraocular routes to commercial chickens carrying maternally-derived antibodies (MDAs) are still protective against ILT. In this study, a recombinant NDV (rNDV) was generated to express infectious laryngotracheitis virus (ILTV) glycoprotein B (gB), named rLS-gB, based on a full-length cDNA clone of the LaSota strain. The protective effect of different doses of rLS-gB administered by spray vaccination to commercial chickens at 1 d of age (doa) was evaluated. The chickens were exposed to 160-µm aerosol particles for 10 min for spray vaccination, and no adverse reactions were observed after vaccination. Despite the presence of anti-NDV MDAs and anti-ILTV MDAs in chickens, the ILTV- and NDV-specific antibody titres were significantly greater in the vaccinated groups than in the unvaccinated group. After challenge with a virulent ILTV strain, no clinical signs were observed in the 107 EID50/ml group compared to the other groups. Furthermore, vaccination with 107 EID50/ml rLS-gB significantly reduced the ILTV viral load and ameliorated gross and microscopic lesions in the trachea of chickens. Overall, these results suggested that rLS-gB is a safe and efficient candidate spray vaccine for ILT and is especially suitable for scaled chicken farms.

Genotoxicity and safety pharmacology of the rVSVInd(GML)-mspSGtc vaccine against SARS-CoV-2 in Sprague-Dawley rats and Beagle dogs.

The emergence of coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to a pandemic, prompting rapid vaccine development. Although vaccines are effective, the occurrence of rare adverse events following vaccination highlights the necessity of determining whether the benefits outweigh the risks posed by the infection itself. The recombinant Vesicular Stomatitis Virus (rVSV) platform is a promising vector for vaccines against emerging viruses. However, limited studies have evaluated the genotoxicity and safety pharmacology of this viral vector vaccine, which is crucial to ensure the safety of vaccines developed using this platform. Hence, the present study aimed to assess the genotoxicity and safety pharmacology of the rVSVInd(GML)-mspSGtc COVID-19 vaccine using micronucleus and comet assays, as well as neurobehavioral, body temperature, respiratory, and cardiovascular assessments in Sprague-Dawley rats and beagle dogs. The intramuscular administration of rVSVInd(GML)-mspSGtc at doses up to 1.5 × 109 PFU/animal did not increase the number of bone marrow micronucleated polychromatic erythrocytes or cause liver DNA damage. Additionally, it had no significant impact on neurobehavioral functions in rats and showed marginal temporary changes in body temperature, respiratory rate, heart rate, and electrocardiogram parameters in rats and dogs, all of which resolved within 24 h. Overall, following genotoxicity and pharmacological safety assessments, rVSVInd(GML)-mspSGtc displayed no notable systemic adverse effects in rats and dogs, suggesting its potential as a vaccine candidate for human clinical trials.

Pre-existing humoral immunity and CD4+ T cell response correlate with cross-reactivity against SARS-CoV-2 Omicron subvariants after heterologous prime-boost vaccination.

BACKGROUND: Information regarding the heterologous prime-boost COVID vaccination has been fully elucidated. The study aimed to evaluate both humoral, cellular immunity and cross-reactivity against variants after heterologous vaccination. METHODS: We recruited healthcare workers previously primed with Oxford/AstraZeneca ChAdOx1-S vaccines and boosted with Moderna mRNA-1273 vaccine boost to evaluate the immunological response. Assay used: anti-spike RBD antibody, surrogate virus neutralizing antibody and interferon-γ release assay. RESULTS: All participants exhibited higher humoral and cellular immune response after the booster regardless of prior antibody level, but those with higher antibody level demonstrated stronger booster response, especially against omicron BA.1 and BA.2 variants. The pre-booster IFN-γ release by CD4+ T cells correlates with post-booster neutralizing antibody against BA.1 and BA.2 variant after adjustment with age and gender. CONCLUSIONS: A heterologous mRNA boost is highly immunogenic. The pre-existing neutralizing antibody level and CD4+ T cells response correlates with post-booster neutralization reactivity against the Omicron variant.

COVID-19 Adenoviral Vector Vaccination Elicits a Robust Memory B Cell Response with the Capacity to Recognize Omicron BA.2 and BA.5 Variants.

Following the COVID-19 pandemic, novel vaccines have successfully reduced severe disease and death. Despite eliciting lower antibody responses, adenoviral vector vaccines are nearly as effective as mRNA vaccines. Therefore, protection against severe disease may be mediated by immune memory cells. We here evaluated plasma antibody and memory B cells (Bmem) targeting the SARS-CoV-2 Spike receptor-binding domain (RBD) elicited by the adenoviral vector vaccine ChAdOx1 (AstraZeneca), their capacity to bind Omicron subvariants, and compared this to the response to mRNA BNT162b2 (Pfizer-BioNTech) vaccination. Whole blood was sampled from 31 healthy adults pre-vaccination and 4 weeks after dose one and dose two of ChAdOx1. Neutralizing antibodies (NAb) against SARS-CoV-2 were quantified at each time point. Recombinant RBDs of the Wuhan-Hu-1 (WH1), Delta, BA.2, and BA.5 variants were produced for ELISA-based quantification of plasma IgG and incorporated separately into fluorescent tetramers for flow cytometric identification of RBD-specific Bmem. NAb and RBD-specific IgG levels were over eight times lower following ChAdOx1 vaccination than BNT162b2. In ChAdOx1-vaccinated individuals, median plasma IgG recognition of BA.2 and BA.5 as a proportion of WH1-specific IgG was 26% and 17%, respectively. All donors generated resting RBD-specific Bmem, which were boosted after the second dose of ChAdOx1 and were similar in number to those produced by BNT162b2. The second dose of ChAdOx1 boosted Bmem that recognized VoC, and 37% and 39% of WH1-specific Bmem recognized BA.2 and BA.5, respectively. These data uncover mechanisms by which ChAdOx1 elicits immune memory to confer effective protection against severe COVID-19.

Immunogenicity and protective efficacy of a recombinant adenovirus containing the fusion protein of bovine parainfluenza virus type 3 genotype C in mice.

Bovine parainfluenza virus type 3 (BPIV3) is a viral respiratory pathogen of cattle that causes substantial economic losses. A replicating-defective recombinant human adenovirus type 5 (HAd5), carrying a fusion protein of BPIV3 genotype C (HAd5-F), was constructed and evaluated for its immunogenicity and protective efficacy in mice. After intramuscular injection with the HAd5-F, the IgG titers against F proteins increased to 1:102,400, and virus-neutralizing titers increased to 1:256, significantly higher than those in the group injected with inactivated BPIV3C in mice (p<0.05). The splenic CD4+/CD8+T lymphocytes and IFN-γ+/IL-4+ cytokine percentages were more significant in the HAd5-F group than those in the control group. A BPIV3C challenge in a mouse model was used to assess protective efficacy of the HAd5-F. The viral loads in the lungs and tracheas of mice immunized with the HAd5-F were significantly lower than those in the control group (p<0.0001). There were no significant histopathological alterations in the lungs of mice vaccinated with the HAd5-F. These findings suggested that the HAd5-F elicited excellent immunity against BPIV3C infection.

Creation of poxvirus expressing foot-and-mouth and peste des petits ruminant disease virus proteins.

OBJECTIVE: Foot-and-mouth disease (FMD) and Peste des petits ruminant disease (PPR) are acute and severe infectious diseases of sheep and are listed as animal diseases for compulsory immunization. However, there is no dual vaccine to prevent these two diseases. The Modified Vaccinia virus Ankara strain (MVA) has been widely used in the construction of recombinant live vector vaccine because of its large capacity of foreign gene, wide host range, high safety, and immunogenicity. In this study, MVA-GFP recombinant virus skeleton was used to construct dual live vector vaccines against FMD and PPR. METHODS: The recombinant plasmid pUC57-FMDV P1-2A3CPPRV FH was synthesized and transfected into MVA-GFP infected CEF cells for homologous recombination. RESULTS: The results showed that a recombinant virus without fluorescent labeling was obtained after multiple rounds of plaque screening. The recombinant virus successfully expressed the target proteins, and the empty capsid of FMDV could be observed by transmission electron microscope (TME), and the expression levels of foreign proteins (VP1 and VP3) detected by ELISA were like those detected in FMDV-infected cells. This study laid the foundation for the successful construction of a live vector vaccine against FMD and PPR. KEY POINTS: • A recombinant MVA expressing FMDVP12A3C and PRRV HF proteins • Both the FMDV and PRRV proteins inserted into the virus were expressed • The proteins expressed by the recombinant poxvirus were assembled into VLPs.

Evaluation the efficacy of oral immunization of broiler chickens with a recombinant Lactobacillus casei vaccine vector expressing the Carboxy-terminal fragment of α-toxin from Clostridium perfringens.

BACKGROUND: Clostridium perfringens (C. perfringens) is a serious anaerobic enteric pathogen causing necrotic enteritis (NE) in broiler chickens. Following the ban on antibiotics as growth promoters in animal feedstuffs, there has been a remarkable rise in occurrence of NE which resulted in considering alternative approaches, particularly vaccination. The objective of this work was to evaluate the recombinant Lactobacillus casei (L. casei) expressing the C-terminal domain of α-toxin from C. perfringens as a potential probiotic-based vaccine candidate to immunize the broiler chickens against NE. RESULTS: The broiler chickens immunized orally with recombinant vaccine strain were significantly protected against experimental NE challenge, and developed specific serum anti-α antibodies. Additionally, the immunized birds showed higher body weight gains compared with control groups during the challenge experiment. CONCLUSIONS: The current study showed that oral immunization of broiler chickens with a safe probiotic-based vector vaccine expressing α-toxin from C. perfringens could provide protective immunity against NE in birds.

A recombinant baculovirus vector vaccine (BacMCP) against the infectious spleen and kidney necrosis virus (ISKNV).

The infectious spleen and kidney necrosis virus (ISKNV) is a highly lethal virus, which has brought significant losses to aquaculture. Therefore, a new vaccine against ISKNV with high efficiency, safety and convenience must be developed. While baculoviruses are more commonly used as protein expression systems for vaccine antigen production, this paper used baculovirus technology to develop a live-vector vaccine, BacMCP, which contains the coding sequence of the major capsid protein (MCP) (GenBank accession no. AF371960) of ISKNV and is driven by a CMV promoter. Real-time PCR and immunofluorescence showed that the MCP gene was successfully delivered to and expressed in fish cells and tissues inoculated with BacMCP. Immune-related gene (IgM, TGF-ß, IL-1, IL-8, TNF-α) expression was induced in BacMCP-treated groups of largemouth bass compared with control groups. Specific antibodies could be detected in the serum of BacMCP injection-vaccinated largemouth bass by ELISA. After injection or immersion vaccination with BacMCP for 21 days, largemouth bass were infected with ISKNV. The immune effect of the injected immunization on fish in different sizes was evaluated. The vaccine efficacy of injection-vaccinated bass was 100% in small bass and 85.7% in large bass. The vaccine efficacy of immersion-vaccinated small bass was 77.3%. This study suggested that BacMCP can be used as a vector-based vaccine candidate to prevent the diseases caused by ISKNV infection.

Serological response and safety of heterologous ChAdOx1-nCoV-19/mRNA-1273 prime-boost vaccination with a twelve-week interval.

The appropriate interval between heterologous prime adenoviral vectored vaccination and boost mRNA vaccination remains unclear. We recruited 100 adult participants to receive a prime adenoviral vectored vaccine (ChAdOx1, AstraZeneca) and a boost mRNA vaccine (mRNA-1273, Moderna) 12 weeks apart and checked their serum SARS-CoV-2 anti-spike IgG titers and neutralizing antibody titers against B.1.1.7 (alpha) and B.1.617.2 (delta) variants on the 28th day after the boost dose. Results were compared with our previous study cohorts who received the same prime-boost vaccinations at 4- and 8-week intervals. Compared to other heterologous vaccination groups, the 12-week interval group had higher neutralizing antibody titers against SARS-CoV-2 variants than the 4-week interval group and was similar to the 8-week interval group at day 28. Adverse reactions after the boost dose were mild and transient. Our results support deploying viral vectored and mRNA vaccines in a flexible schedule with intervals from 8 to 12 weeks.

Perspectives from recent advances of Helicobacter pylori vaccines research.

BACKGROUND: Helicobacter pylori (H. pylori) infection is the main factor leading to some gastric diseases. Currently, H. pylori infection is primarily treated with antibiotics. However, with the widespread application of antibiotics, H. pylori resistance to antibiotics has also gradually increased year by year. Vaccines may be an alternative solution to clear H. pylori. AIMS: By reviewing the recent progress on H. pylori vaccines, we expected it to lead to more research efforts to accelerate breakthroughs in this field. MATERIALS & METHODS: We searched the research on H. pylori vaccine in recent years through PubMed®, and then classified and summarized these studies. RESULTS: The study of the pathogenic mechanism of H. pylori has led to the development of vaccines using some antigens, such as urease, catalase, and heat shock protein (Hsp). Based on these antigens, whole-cell, subunit, nucleic acid, vector, and H. pylori exosome vaccines have been tested. DISCUSSION: At present, researchers have developed many types of vaccines, such as whole cell vaccines, subunit vaccines, vector vaccines, etc. However, although some of these vaccines induced protective immunity in mouse models, only a few were able to move into human trials. We propose that mRNA vaccine may play an important role in preventing or treating H. pylori infection. The current study shows that we have developed various types of vaccines based on the virulence factors of H. pylori. However, only a few vaccines have entered human clinical trials. In order to improve the efficacy of vaccines, it is necessary to enhance T-cell immunity. CONCLUSION: We should fully understand the pathogenic mechanism of H. pylori and find its core antigen as a vaccine target.

Epidemiological aspects of headache after different types of COVID-19 vaccines: An online survey.

BACKGROUND: Coronavirus disease 2019 (COVID-19) vaccine-related side effects are a key concern with the emergence of various types of vaccines in the market. We aimed to assess the frequency and characteristics of headache following different types of COVID-19 vaccines. METHODS: Fully vaccinated people were recruited by a convenience sample through an online survey from September 1 to December 1, 2021. Detailed analysis of headache following vaccination was investigated. Participants with a history of pre-existing headaches were telephone interviewed by a neurologist to ascertain the type of headache. RESULTS: A total of 1372 participants participated (mean age 32.9 ± 11.1). The highest frequency of headache was reported with the adenoviral vector type (302/563, 53.6%), followed by mRNA vaccines (129/269, 48%) and then the inactivated type (188/540, 34.8%). Recipients of the adenoviral vector type had a significantly longer latency between vaccination and the headache onset (median 8 h [5:12]) than recipients of the inactivated type (median 4 h [2:8], p < 0.001). Headache intensity was significantly higher with the adenoviral vector type (median 6 [5:8]) than with the inactivated type (median 5 [4:7], p < 0.001). Adenoviral vector vaccines would increase the likelihood of headache by 2.38 times more than inactivated vaccines (odds ratio [OR] 2.38, 95% confidence interval [CI] 1.83-3.04, p < 0.001). Female sex and thyroid disease were significantly associated with headache related to COVID-19 vaccines (OR 1.52, 95% CI 1.16-1.99; OR 3.97, 95% CI 1.55-10.2, respectively). CONCLUSION: Recipients of the COVID-19 vaccine should be counseled that they may experience headaches, especially after the adenoviral vector type. However, the intensity of such headache is mild to moderate and can resolve within a few days. Based on the current study design and the potential recall bias, these results may not be generalizable and should be preliminary.

SARS-CoV-2 vaccination-induced cutaneous vasculitis: Report of two new cases and literature review.

Currently the most powerful tool in combating the COVID-19 pandemic is vaccination against SARS-CoV-2. A growing percentage of the world's population is being vaccinated. Various vaccines are worldwide on the market. Several adverse reactions have been reported as a part of post-marketing surveillance of COVID-19 vaccines. Among the possible adverse events, cutaneous vasculitis has occasionally been reported. We present a narrative review on cutaneous vasculitis related to COVID-19-vaccination to summarize clinical findings, histopathology, treatment and outcome. We searched for "COVID vaccine", "COVID vaccination" AND "cutaneous vasculitis" in PUBMED. Articles in English have been selected, from inception to December 2021, and analyzed for patient's characteristics, type of vaccine, time of appearance of cutaneous vasculitis and clinico-histopathologic type. Treatment and outcome have also been considered in this narrative review. Two new unpublished cases of ours were added. Cutaneous vasculitis is a rare adverse event to COVID-19 vaccination. It has been observed with mRNA and adenovirus-vector vaccines. IgA vasculitis, lymphocytic and ANCA-associated vasculitis, leukocytoclastic and urticarial vasculitis have been reported. This adverse event can occur after first or second shot. Most cases run a mild to moderate course. Cornerstone of medical treatment are systemic corticosteroids. Complete remission could be achieved in most patients. Vasculitis may not be considered as a contraindication of vaccination, being uncommonly reported and shows a favorable prognosis. The benefit of the vaccination remains high especially for immunocompromised patients. COVID-vaccine induced vasculitis is important in the differential diagnosis of purpuric and vasculitis disorders.

Lactobacillus casei displaying Clostridium perfringens NetB antigen protects chickens against necrotic enteritis.

Necrotic enteritis is a serious economical disease of poultry caused by Clostridium perfringens. NetB toxin of Clostridium perfringens is considered the causative agent of necrotic enteritis. Following the withdrawal of in-feed antibiotic growth promoters, there has been an urgent need to develop alternative approaches such as vaccination. Currently, there are no commercially available vaccines to control necrotic enteritis especially in broiler chickens as the target population. In the present study, we constructed a recombinant Lactobacillus casei strain expressing NetB protein of C. perfringens on the cell surface and used this probiotic-based vaccine strain to immunize broiler chickens orally against experimental induction of necrotic enteritis. The birds immunized with the oral vaccine strain were significantly protected against necrotic enteritis challenge and developed strong serum anti-NetB antibody responses to NetB protein. Furthermore, the immunized birds showed higher body weight gains during the challenge experiment compared with control birds. This study showed, for the first time, that a probiotic-based vector vaccine could be a promising vaccine candidate to provide protection against necrotic enteritis in broiler chickens. KEYPOINTS: • The probiotic L. casei carrying pT1NX-netB plasmid displayed NetB antigen on the cell surface. • The LC-NetB vaccine strain induced high anti-toxin antibody response in broiler chickens. • The LC-NetB vector vaccine provided significant protection against experimental NE challenge.

Cytolysin A-mediated protein exportation efficiency and its role in enhancing the fitness of live recombinant Salmonella Typhi vaccine strain.

The genetic fusion of cytolysin A (clyA) to heterologous antigen expressed in live Salmonella vector demonstrated efficient translocation into periplasmic space and extracellular medium. Accumulating evidence has shown that clyA-mediated antigen delivery improved growth fitness and enhanced immunogenicity of live vector vaccine, but the factors influencing this protein exportation has not been investigated. In this study, Toxoplasma gondii antigen fused at C-terminal of clyA protein was expressed in live S. Typhi vector via both plasmid and chromosomal-based expressions. The bivalent strains showed comparable growth rates as monovalent strains, but in varies antigen exportation efficiency. ClyA-fusion antigen with positive charges was translocated to the extracellular spaces, whereas those with negative charges were retained in the cytoplasm. Furthermore, excessive cellular resources expenditure on antigen expression, especially antigen with larger size, could limit the clyA-fusion antigen exportation, resulting in undesirable metabolic burden that eventually affects the growth fitness. Altogether, the present work indicates potential linkage of factors mainly on antigen properties and expression platforms that may affect clyA-mediated antigen delivery to enhance the growth fitness of live vector strain.

Immune response and safety of heterologous ChAdOx1-nCoV-19/mRNA-1273 vaccination compared with homologous ChAdOx1-nCoV-19 or homologous mRNA-1273 vaccination.

BACKGROUND/PURPOSE: Efficacy and safety data of heterologous prime-boost vaccination against SARS-CoV-2 remains limited. METHODS: We recruited adult volunteers for homologous or heterologous prime-boost vaccinations with adenoviral (ChAdOx1, AstraZeneca) and/or mRNA (mRNA-1273, Moderna) vaccines. Four groups of prime-boost vaccination schedules were designed: Group 1, ChAdOx1/ChAdOx1 8 weeks apart; Group 2, ChAdOx1/mRNA-1273 8 weeks apart; Group 3, ChAdOx1/mRNA-1273 4 weeks apart; and Group 4, mRNA-1273/mRNA-1273 4 weeks apart. The primary outcome was serum anti-SARS-CoV-2 IgG titers and neutralizing antibody titers against B.1.1.7 (alpha) and B.1.617.2 (delta) variants on day 28 after the second dose. Adverse events were recorded up until 84 days after the second dose. RESULTS: We enrolled 399 participants with a median age of 41 years and 75% were female. On day 28 after the second dose, the anti-SARS-CoV-2 IgG titers of both heterologous vaccinations (Group 2 and Group 3) were significantly higher than that of homologous ChAdOx1 vaccination (Group 1), and comparable with homologous mRNA-1273 vaccination (Group 4). The heterologous vaccination group had better neutralizing antibody responses against the alpha and delta variant as compared to the homologous ChAdOx1 group. Most of the adverse events (AEs) were mild and transient. AEs were less frequent when heterologous boosting was done at 8 weeks rather than at 4 weeks. CONCLUSION: Heterologous ChAdOx1/mRNA-1273 vaccination provided higher immunogenicity than homologous ChAdOx1 vaccination and comparable immunogenicity with the homologous mRNA-1273 vaccination. Our results support the safety and efficacy of heterologous prime-boost vaccination using the ChAdOx1 and mRNA-1273 COVID-19 vaccines. (ClinicalTrials.gov number, NCT05074368).

Covid-19 in kidney transplant recipients.

Kidney transplant recipients are a very vulnerable population at risk of severe course and death from Covid-19. Several antiviral drugs are now available for the treatment of nonhospitalized individuals with mild to moderate Covid-19 and hospitalized patients with severe disease. The combination of monoclonal antibodies is also available to be used as pre-exposure prophylaxis in elderly patients. Previously used monoclonal antibodies for post-exposure prophylaxis are no longer effective because of the new mutations and are no longer recommended. Although the immune response to Covid-19 vaccines is impaired in kidney transplant recipients, the effectiveness of the Covid-19 vaccines was described even in this immunocompromised group. Therefore vaccination, together with anti-epidemic measures, remains the most important tool to prevent Covid-19.

Orf Virus-Based Therapeutic Vaccine for Treatment of Papillomavirus-Induced Tumors.

Orf virus (ORFV) represents a suitable vector for the generation of efficient, prophylactic antiviral vaccines against different pathogens. The present study investigated for the first time the therapeutic application of ORFV vector-based vaccines against tumors induced by cottontail rabbit papillomavirus (CRPV). ORFV-CRPV recombinants were constructed expressing the early CRPV gene E1, E2, E7, or LE6. In two independent experiments we used in total 23 rabbits which were immunized with a mixture of the four ORFV-CRPV recombinants or empty ORFV vector as a control 5 weeks after the appearance of skin tumors. For the determination of the therapeutic efficacy, the subsequent growth of the tumors was recorded. In the first experiment, we could demonstrate that three immunizations of rabbits with high tumor burden with the combined four ORFV-CRPV recombinants resulted in significant growth retardation of the tumors compared to the control. A second experiment was performed to test the therapeutic effect of 5 doses of the combined vaccine in rabbits with a lower tumor burden than in nonimmunized rabbits. Tumor growth was significantly reduced after immunization, and one vaccinated rabbit even displayed complete tumor regression until the end of the observation period at 26 weeks. Results of delayed-type hypersensitivity (DTH) skin tests suggest the induction of a cellular immune response mediated by the ORFV-CRPV vaccine. The data presented show for the first time a therapeutic potential of the ORFV vector platform and encourage further studies for the development of a therapeutic vaccine against virus-induced tumors.IMPORTANCE Viral vectors are widely used for the development of therapeutic vaccines for the treatment of tumors. In our study we have used Orf virus (ORFV) strain D1701-V for the generation of recombinant vaccines expressing cottontail rabbit papillomavirus (CRPV) early proteins E1, E2, LE6, and E7. The therapeutic efficacy of the ORFV-CRPV vaccines was evaluated in two independent experiments using the outbred CRPV rabbit model. In both experiments the immunization achieved significant suppression of tumor growth. In total, 84.6% of all outbred animals benefited from the ORFV-CRPV vaccination, showing reduction in tumor size and significant tumor growth inhibition, including one animal with complete tumor regression without recurrence.

Comparison of vaccine-induced thrombotic events between ChAdOx1 nCoV-19 and Ad26.COV.2.S vaccines.

Cerebral venous thrombosis (CVT) events have been reported after vaccination with adenoviral COVID-19 vector vaccines. This study aimed to compare the clinical presentations and courses of vaccine-induced thrombotic thrombocytopenia (VITT) between the two adenoviral vector vaccines, Ad26.COV.2.S (Janssen/Johnson & Johnson) and ChAdOx1 nCoV-19 (Astra-Zeneca). We found that CVT after Ad26.COV.2.S vaccination presents later with similar symptoms compared to CVT after administration of ChAdOx1 nCoV-19, albeit with more thrombosis and intracerebral hemorrhage, lower D-dimer and aPTT levels but similar mortality. These findings could help guide clinical assessment and management of CVT after COVID-19 vaccination.

Construction and immune efficacy of recombinant Lactobacillus casei expressing OmpAI of Aeromonas veronii C5-I as molecular adjuvant.

Despite advancements in diagnosis and control, Aeromonas infections are considered the leading cause of economic aquaculture loss. In this study, to enhance DNA vaccine efficacy against Aeromonas infections, a fused DNA fragment (1504 bp) of the OmpAI gene from Aeromonas veronii (A. veronii) combined with the C5-I gene from the common carp was generated with splicing by overlapping PCR (SOE-PCR) and expressed in Lactobacillus casei strain CC16. Protein C5-I served as a molecular adjuvant for the antigen OmpAI. Two types of fusion antigens were developed (anchored and secretory). Generally, anchored-type antigens are more effective in inducing immune responses in fish than secretory antigens. Western blot analysis showed that the bands of both antigens were present at 58 kDa. After oral immunization, both DNA vaccines enhanced the serum levels of AKP, ACP, SOD and LZM in immunized carp; the genes IL-10, IL-1ß, TNF-α, and IFN-γ in the heart, liver, spleen, head kidney, and intestinal tract were upregulated; and a stronger phagocytic response was triggered in immunized fish. In addition, common carp administered the fused antigens were more protected from Aeromonas challenge (60-73.3% protection). Recombinant Lactobacillus bacteria expressing the fused protein showed a greater propensity for colonization in the intestinal tract in immunized fish than in controls. Here, we provide a promising approach to improve DNA vaccine immunogenicity for protecting common carp from A. veronii infections.