Recombinant Marek's disease virus type 1 provides full protection against H9N2 influenza A virus in chickens.

The H9N2 subtype of the avian influenza virus (AIV) poses a significant threat to the poultry industry and human health. Recombinant vaccines are the preferred method of controlling H9N2 AIV, and Marek's disease virus (MDV) is the ideal vector for recombinant vaccines. During this study, we constructed two recombinant MDV type 1 strains that carry the hemagglutinin (HA) gene of AIV to provide dual protection against both AIV and MDV. To assess the effects of different MDV insertion sites on the protective efficacy of H9N2 AIV, the HA gene of H9N2 AIV was inserted in UL41 and US2 of the MDV type 1 vector backbone to obtain recombinant viruses rMDV-UL41/HA and rMDV-US2/HA, respectively. An indirect immunofluorescence assay showed sustained expression of HA protein in both recombinant viruses. Additionally, the insertion of the HA gene in UL41 and US2 did not affect MDV replication in cell cultures. After immunization of specific pathogen-free chickens, although both the rMDV-UL41/HA and rMDV-US2/HA groups exhibited similar levels of hemagglutination inhibition antibody titers, only the rMDV-UL41/HA group provided complete protection against the H9N2 AIV challenge, and also offered complete protection against challenge with MDV. These results demonstrated that rMDV-UL41/HA could be used as a promising bivalent vaccine strain against both H9N2 avian influenza and Marek's disease in chickens.

Pan-beta-coronavirus subunit vaccine prevents SARS-CoV-2 Omicron, SARS-CoV, and MERS-CoV challenge.

Three highly pathogenic coronaviruses (CoVs), SARS-CoV-2, SARS-CoV, and MERS-CoV, belonging to the genus beta-CoV, have caused outbreaks or pandemics. SARS-CoV-2 has evolved into many variants with increased resistance to the current vaccines. Spike (S) protein and its receptor-binding domain (RBD) fragment of these CoVs are important vaccine targets; however, the RBD of the SARS-CoV-2 Omicron variant is highly mutated, rending neutralizing antibodies elicited by ancestral-based vaccines targeting this region ineffective, emphasizing the need for effective vaccines with broad-spectrum efficacy against SARS-CoV-2 variants and other CoVs with pandemic potential. This study describes a pan-beta-CoV subunit vaccine, Om-S-MERS-RBD, by fusing the conserved and highly potent RBD of MERS-CoV into an RBD-truncated SARS-CoV-2 Omicron S protein, and evaluates its neutralizing immunogenicity and protective efficacy in mouse models. Om-S-MERS-RBD formed a conformational structure, maintained effective functionality and antigenicity, and bind efficiently to MERS-CoV receptor, human dipeptidyl peptidase 4, and MERS-CoV RBD or SARS-CoV-2 S-specific antibodies. Immunization of mice with Om-S-MERS-RBD and adjuvants (Alum plus monophosphoryl lipid A) induced broadly neutralizing antibodies against pseudotyped MERS-CoV, SARS-CoV, and SARS-CoV-2 original strain, as well as T-cell responses specific to RBD-truncated Omicron S protein. Moreover, the neutralizing activity against SARS-CoV-2 Omicron subvariants was effectively improved after priming with an Omicron-S-RBD protein. Adjuvanted Om-S-MERS-RBD protein protected mice against challenge with SARS-CoV-2 Omicron variant, MERS-CoV, and SARS-CoV, significantly reducing viral titers in the lungs. Overall, these findings indicated that Om-S-MERS-RBD protein could develop as an effective universal subunit vaccine to prevent infections with MERS-CoV, SARS-CoV, SARS-CoV-2, and its variants. IMPORTANCE: Coronaviruses (CoVs), SARS-CoV-2, SARS-CoV, and MERS-CoV, the respective causative agents of coronavirus disease 2019, SARS, and MERS, continually threaten human health. The spike (S) protein and its receptor-binding domain (RBD) fragment of these CoVs are critical vaccine targets. Nevertheless, the highly mutated RBD of SARS-CoV-2 variants, especially Omicron, significantly reduces the efficacy of current vaccines against SARS-CoV-2 variants. Here a protein-based pan-beta-CoV subunit vaccine is designed by fusing the potent and conserved RBD of MERS-CoV into an RBD-truncated Omicron S protein. The resulting vaccine maintained effective functionality and antigenicity, induced broadly neutralizing antibodies against all of these highly pathogenic human CoVs, and elicited Omicron S-specific cellular immune responses, protecting immunized mice from SARS-CoV-2 Omicron, SARS-CoV, and MERS-CoV infections. Taken together, this study rationally designed a pan-beta-CoV subunit vaccine with broad-spectrum efficacy, which has the potential for development as an effective universal vaccine against SARS-CoV-2 variants and other CoVs with pandemic potential.

Immunogenicity and Protective Efficacy of Aerosolized Live-Attenuated Yellow Fever 17D Vaccine in Mice.

Yellow fever (YF), caused by the yellow fever virus (YFV), continually spreads and causes epidemics worldwide, posing a great threat to human health. The live-attenuated YF 17D vaccine (YF-17D) has been licensed for preventing YFV infection and administrated via the intramuscular (i.m.) route. In this study, we sought to determine the immunogenicity and protective efficacy of aerosolized YF-17D via the intratracheal (i.t.) route in mice. YF-17D stocks in liquids were successfully aerosolized into particles of 6 µm. Further in vitro phenotype results showed the aerosolization process did not abolish the infectivity of YF-17D. Meanwhile, a single i.t. immunization with aerosolized YF-17D induced robust humoral and cellular immune responses in A129 mice, which is comparable to that received i.p. immunization. Notably, the aerosolized YF-17D also triggered specific secretory IgA (SIgA) production in bronchoalveolar lavage. Additionally, all immunized animals survived a lethal dose of YFV challenge in mice. In conclusion, our results support further development of aerosolized YF-17D in the future.

Development of the first officially licensed live attenuated duck hepatitis A virus type 3 vaccine strain HB80 in China and its protective efficacy against DHAV-3 infection in ducks.

Duck hepatitis A virus type 3 (DHAV-3) is an infectious virus that is highly fatal to ducklings and causes significant economic losses in the duck industry worldwide. Biosecurity and vaccination are required to control the pathogen. In the present study, we attenuated a lowly pathogenic DHAV-3 clinical isolate, named as HB, by serial passaging in duck embryos, and followed by several adaptive proliferations in specific-pathogen-free (SPF) chicken embryos. The virulence of DHAV-3 at different passages was assessed by infecting 3-day-old ducklings. We found that the HB strain lost pathogenicity to ducklings from the 55th passage onwards. The 80th passage strain (HB80), which achieved good growth capacity in duck embryos with a viral titer of 108.17 50% egg lethal dose per milliliter (ELD50/mL), was selected as a live attenuated vaccine candidate. The HB80 strain did not induce clinical symptoms or pathological lesions in 3-day-old ducklings and showed no virulence reversion after 5 rounds of in vivo back-passage. The minimum effective dose of HB80 was determined to be 104.5 ELD50 by hypodermic inoculation of the neck. Importantly, a single dose of HB80 elicited good immune responses and provided complete protection against challenge with the lethal DHAV-3 strain. Compared with the genomic sequence of the parental HB strain, HB80 had 7 amino acid substitutions, two of them are in the hypervariable region of the VP1 and polymerase-encoding 3D regions, which may play a role in virulence attenuation. Our data suggest that the attenuated HB80 strain is a promising vaccine candidate for the prevention of DHAV-3 infections in China. HB80 has been registered as a New Veterinary Drug Registration Certificate by the Chinese Ministry of Agriculture and Rural Affairs (MARA), and is the first live attenuated DHAV-3 vaccine strain to be officially licensed in China.

Selection of vaccine candidates against Pseudomonas koreensis using reverse vaccinology and a preliminary efficacy trial in Empurau (Tor tambroides).

This study marks the first utilization of reverse vaccinology to develop recombinant subunit vaccines against Pseudomonas koreensis infection in Empurau (Tor tambroides). The proteome (5538 proteins) was screened against various filters to prioritize proteins based on features that are associated with virulence, subcellular localization, transmembrane helical structure, antigenicity, essentiality, non-homology with the host proteome, molecular weight, and stability, which led to the identification of eight potential vaccine candidates. These potential vaccine candidates were cloned and expressed, with six achieving successful expression and purification. The antigens were formulated into two distinct vaccine mixtures, Vac A and Vac B, and their protective efficacy was assessed through in vivo challenge experiments. Vac A and Vac B demonstrated high protective efficacies of 100 % and 81.2 %, respectively. Histological analyses revealed reduced tissue damage in vaccinated fish after experimental infection, with Vac A showing no adverse effects, whereas Vac B exhibited mild degenerative changes. Quantitative real-time PCR results showed a significant upregulation of TNF-α and downregulation of IL-1ß in the kidneys, spleen, gills, and intestine in both Vac A- and Vac B-immunized fish after challenged with P. koreensis. Additionally, IL-8 exhibits tissue-specific differential expression, with significant upregulation in the kidney, gills, and intestine, and downregulation in the spleen, particularly notable in Vac A-immunized fish. The research underscores the effectiveness of the reverse vaccinology approach in fish and demonstrates the promising potential of Vac A and Vac B as recombinant subunit vaccines.

Protective efficacy of Eimeria maxima EmLPL and EmTregIM-1 against homologous challenge in chickens.

Chicken coccidiosis has inflicted significant economic losses upon the poultry industry. The primary strategies for preventing and controlling chicken coccidiosis include anticoccidial drugs and vaccination. However, these approaches face limitations, such as drug residues and resistance associated with anticoccidial drugs, and safety concerns related to live vaccines. Consequently, the urgent development of innovative vaccines, such as subunit vaccines, is imperative. In previous study, we screened 2 candidate antigens: Eimeria maxima lysophospholipase (EmLPL) and E. maxima regulatory T cell inducing molecule 1 (EmTregIM-1). To investigate the immune protective effect of the 2 candidate antigens against Eimeria maxima (E. maxima) infection, we constructed recombinant plasmids, namely pET-28a-EmLPL and pET-28a-EmTregIM-1, proceeded to induce the expression of recombinant proteins of EmLPL (rEmLPL) and EmTregIM-1 (rEmTregIM-1). The immunogenic properties of these proteins were confirmed through western blot analysis. Targeting EmLPL and EmTregIM-1, we developed subunit vaccines and encapsulated them in PLGA nanoparticles, resulting in nano-vaccines: PLGA-rEmLPL and PLGA-rEmTregIM-1. The efficacy of these vaccines was assessed through animal protection experiments. The results demonstrated that rEmLPL and rEmTregIM-1 were successfully recognized by anti-E. maxima chicken sera and His-conjugated mouse monoclonal antibodies. Immunization with both subunit and nano-vaccines containing EmLPL and EmTregIM-1 markedly mitigated weight loss and reduced oocyst shedding in chickens infected with E. maxima. Furthermore, the anticoccidial indexes (ACI) for both rEmLPL and PLGA-rEmLPL exceeded 160, whereas those for rEmTregIM-1 and PLGA-rEmTregIM-1 were above 120 but did not reach 160, indicating superior protective efficacy of the rEmLPL and PLGA-rEmLPL formulations. By contrast, the protection afforded by rEmTregIM-1 and PLGA-rEmTregIM-1 was comparatively lower. Thus, EmLPL is identified as a promising candidate antigen for vaccine development against E. maxima infection.

Virus-like particle-based multipathogen vaccine of FMD and SVA elicits balanced and broad protective efficacy in mice and pigs.

Inactivated vaccines lack the capability to serologically differentiate between infected and vaccinated animals, thereby impeding the effective eradication of pathogen. Conversely, vaccines based on virus-like particles (VLPs) emulate natural viruses in both size and antigenic structure, presenting a promising alternative to overcome these limitations. As the complexity of swine infectious diseases increases, the increase of vaccine types and doses may intensify the stress response. This exacerbation can lead to diminished productivity, failure of immunization, and elevated costs. Given the critical dynamics of co-infection and the clinically indistinguishable symptoms associated with foot-and-mouth disease virus (FMDV) and senecavirus A (SVA), there is a dire need for an efficacious intervention. To address these challenges, we developed a combined vaccine composed of three distinct VLPs, specifically designed to target SVA and FMDV serotypes O and A. Our research demonstrates that this trivalent VLP vaccine induces antigen-specific and robust serum antibody responses, comparable to those produced by the respective monovalent vaccines. Moreover, the immune sera from the combined VLP vaccine strongly neutralized FMDV type A and O, and SVA, with neutralization titers comparable to those of the individual vaccines, indicating a high level of immunogenic compatibility among the three VLP components. Importantly, the combined VLPs vaccines-immunized sera conferred efficient protection against single or mixed infections with FMDV type A and O, and SVA viruses in pigs. In contrast, individual vaccines could only protect pigs against homologous virus infections and not against heterologous challenges. This study presents a novel combined vaccines candidate against FMD and SVA, and provides new insights for the development of combination vaccines for other viral swine diseases.

Dynamics of anti-SARS-CoV-2 IgG antibody responses following breakthrough infection and the predicted protective efficacy: A longitudinal community-based population study in China.

OBJECTIVES: To assess the dynamics of the anti-SARS-CoV-2 IgG antibody levels and their efficacy against COVID-19. METHODS: We conducted a longitudinal serological analysis of 852 breakthrough COVID-19 infections among the community-based population in Yichang, China. Anti-SARS-CoV-2 IgG levels were measured by chemiluminescence at approximately 3, 4, and 9 months after infection. A linear mixed model predicted IgG antibody decline over 18 months. The effectiveness of antibodies in preventing symptomatic and severe infections was determined using an existing meta-regression model. RESULTS: IgG antibodies slowly declined after breakthrough infections. Initially high at around 3 months (339.44 AU/mL, IQR: 262.78-382.95 AU/mL), levels remained significant at 9 months (297.74 AU/mL, IQR: 213.22-360.62 AU/mL). The elderly (≥60 years) had lower antibody levels compared to the young (<20 years) (P < 0.001). The protective efficacy of antibodies against symptomatic and severe infections was lower in the elderly (≥60 years) (78.34% and 86.33%) compared to the young (<20 years) (96.56% and 98.75%) after 1 year. CONCLUSION: The study indicated a slow decline in anti-SARS-CoV-2 IgG antibodies, maintaining considerable efficacy for over 1 year. However, lower levels in the elderly suggest reduced protective effects, underscoring the need for age-specific vaccination strategies.

Investigation of the safety and protective efficacy of an attenuated and marker M. bovis-BoHV-1 combined vaccine in bovines.

Bovine respiratory disease (BRD) is one of the most common diseases in the cattle industry worldwide; it is caused by multiple bacterial or viral coinfections, of which Mycoplasma bovis (M. bovis) and bovine herpesvirus type 1 (BoHV-1) are the most notable pathogens. Although live vaccines have demonstrated better efficacy against BRD induced by both pathogens, there are no combined live and marker vaccines. Therefore, we developed an attenuated and marker M. bovis-BoHV-1 combined vaccine based on the M. bovis HB150 and BoHV-1 gG-/tk- strain previously constructed in our lab and evaluated in rabbits. This study aimed to further evaluate its safety and protective efficacy in cattle using different antigen ratios. After immunization, all vaccinated cattle had a normal rectal temperature and mental status without respiratory symptoms. CD4+, CD8+, and CD19+ cells significantly increased in immunized cattle and induced higher humoral and cellular immune responses, and the expression of key cytokines such as IL-4, IL-12, TNF-α, and IFN-γ can be promoted after vaccination. The 1.0 × 108 CFU of M. bovis HB150 and 1.0 × 106 TCID50 BoHV-1 gG-/tk- combined strain elicited the most antibodies while significantly increasing IgG and cellular immunity after challenge. In conclusion, the M. bovis HB150 and BoHV-1 gG-/tk- combined strain was clinically safe and protective in calves; the mix of 1.0 × 108 CFU of M. bovis HB150 and 1.0 × 106 TCID50 BoHV-1 gG-/tk- strain was most promising due to its low amount of shedding and highest humoral and cellular immune responses compared with others. This study introduces an M. bovis-BoHV-1 combined vaccine for application in the cattle industry.

Epigenetic Factor MicroRNAs Likely Mediate Vaccine Protection Efficacy against Lymphomas in Response to Tumor Virus Infection in Chickens through Target Gene Involved Signaling Pathways.

Epigenetic factors, including microRNAs (miRNAs), play an important role in affecting gene expression and, therefore, are involved in various biological processes including immunity protection against tumors. Marek's disease (MD) is a highly contagious disease of chickens caused by the MD virus (MDV). MD has been primarily controlled by vaccinations. MD vaccine efficacy might, in part, be dependent on modulations of a complex set of factors including host epigenetic factors. This study was designed to identify differentially expressed miRNAs in the primary lymphoid organ, bursae of Fabricius, in response to MD vaccination followed by MDV challenge in two genetically divergent inbred lines of White Leghorns. Small RNA sequencing and bioinformatic analyses of the small RNA sequence reads identified hundreds of miRNAs among all the treatment groups. A small portion of the identified miRNAs was differentially expressed within each of the four treatment groups, which were HVT or CVI988/Rispens vaccinated line 63-resistant birds and line 72-susceptible birds. A direct comparison between the resistant line 63 and susceptible line 72 groups vaccinated with HVT followed by MDV challenge identified five differentially expressed miRNAs. Gene Ontology analysis of the target genes of those five miRNAs revealed that those target genes, in addition to various GO terms, are involved in multiple signaling pathways including MAPK, TGF-ß, ErbB, and EGFR1 signaling pathways. The general functions of those pathways reportedly play important roles in oncogenesis, anti-cancer immunity, cancer cell migration, and metastatic progression. Therefore, it is highly likely that those miRNAs may, in part, influence vaccine protection through the pathways.

Estimation of trajectory of protective efficacy in infectious disease prevention trials using recurrent event times.

In studies of infectious disease prevention, the level of protective efficacy of medicinal products such as vaccines and prophylactic drugs tends to vary over time. Many products require administration of multiple doses at scheduled times, as opposed to one-off or continual intervention. Accurate information on the trajectory of the level of protective efficacy over time facilitates informed clinical recommendations and implementation strategies, for example, with respect to the timing of administration of the doses. Based on concepts from pharmacokinetic and pharmacodynamic modeling, we propose a non-linear function for modeling the trajectory after each dose. The cumulative effect of multiple doses of the products is captured by an additive series of the function. The model has the advantages of parsimony and interpretability, while remaining flexible in capturing features of the trajectories. We incorporate this series into the Andersen-Gill model for analysis of recurrent event time data and compare it with alternative parametric and non-parametric functions. We use data on clinical malaria disease episodes from a trial of four doses of an anti-malarial drug combination for chemoprevention to illustrate, and evaluate the performance of the methods using simulation. The proposed method out-performed the alternatives in the analysis of real data in terms of Akaike and Bayesian Information Criterion. It also accurately captured the features of the protective efficacy trajectory such as the area under curve in simulations. The proposed method has strong potential to enhance the evaluation of disease prevention measures and improve their implementation strategies.

Evaluation of immunogenicity and protective efficacy of the outer membrane porin F (OprF) against Pseudomonas plecoglossicida in large yellow croaker (Larimichthys crocea).

Large yellow croaker (Larimichthys crocea) farming dominates the marine aquaculture industry in China. However, the epidemic outbreaks of visceral white nodules disease (VWND), caused by bacterial pathogen Pseudomonas plecoglossicida, have emerged as a significant concern within the large yellow croaker industry. Although vaccination is considered to be an effective method for preventing and controlling P. plecoglossicida infection, there is currently no commercially available vaccine targeting this bacterium. In the present study, the outer membrane porin F (OprF) of P. plecoglossicida was characterized and revealed a high sequence similarity with that of other Pseudomonas species. The recombinant OprF protein (rOprF) produced in Escherichia coli was then evaluated for its immunogenicity and protective role against P. plecoglossicida in large yellow croaker. The rOprF was identified to have immunogenicity by Western blot using large yellow croaker anti-P. plecoglossicida sera. Additionally, the indirect immunofluorescence assay (IIFA) provided evidence indicating the surface exposure of OprF in P. plecoglossicida. Fish vaccinated twice via intraperitoneal (IP) injection with the purified rOprF combined with commercial adjuvant ISA 763A VG exhibited a relative percent survival (RPS) of 70.60% after challenge with virulent P. plecoglossicida strain through immersion. The administration of rOprF resulted in a notable increase in specific serum antibody levels and serum lysozyme activity compared to the control groups. The immune-related genes in the spleen and head kidney of rOprF-vaccinated fish were remarkably upregulated compared with the PBS-vaccinated sham group after the P. plecoglossicida challenge. In summary, the findings of this study suggest that rOprF exhibits considerable potential in inducing a robust immune response, making it a viable candidate for vaccination against P. plecoglossicida infection in large yellow croaker.

Protective effect against toxoplasmosis in BALB/C mice vaccinated with recombinant Toxoplasma gondii CDPK3, GRA35, and ROP46 protein cocktail vaccine.

Toxoplasma gondii (T. gondii) is one of the most common pathogenic protozoa in the world, and causes toxoplasmosis, which in varying degrees causes significant economic losses and poses a serious public health challenge globally. To date, the development of an effective vaccine for human toxoplasmosis remains a challenge. Given that T.gondii calcium-dependent protein kinase 3 (CDPK3), dense granule protein 35 (GRA35) and rhoptry organelle protein 46 (ROP46) play key roles during Toxoplasma gondii invasion of host cells, we developed a protein vaccine cocktail including these proteins and validated its protective efficacy. The specific protective effects of vaccine on mice were analyzed by measuring serum antibodies, cytokines, splenocyte proliferation, the percentage of CD4+ and CD8+ T-lymphocytes, survival rate, and parasite cyst burden. The results showed that mice vaccinated with a three-protein cocktail produced the highest levels of immune protein antibodies to IgG, and high levels of IFN-γ, IL-2, IL-4, and IL-10 compared to other mice vaccinated with two proteins. In addition, CD4+ and CD8+ T cell percentages were significantly elevated. Compared to the control groups, mice vaccinated with the three-protein cocktail survived significantly longer after acute infection with T. gondii and had significantly fewer cysts after chronic infection. These results demonstrated that a cocktail vaccine of TgCDPK3, TgGRA35, and TgROP46 can effectively induce cellular and humoral immune responses with good protective effects in mice, indicating its potential as vaccine candidates for toxoplasmosis.

Oral immunization with recombinant L. lactis expressing GCRV-II VP4 produces protection against grass carp reovirus infection.

The hemorrhagic disease causing by grass carp reovirus (GCRV) infection, is associated with major economic losses and significant impact on aquaculture worldwide. VP4 of GCRV is one of the major outer capsid proteins which can induce an immune response in the host. In this study, pNZ8148-VP4/L. lactis was constructed to express recombinant VP4 protein of GCRV, which was confirmed by the Western-Blot and enzyme-linked immunosorbent assay. Then we performed the oral immunization for rare minnow model and the challenge with GCRV-II. After oral administration, pNZ8148-VP4/L. lactis can continuously reside in the intestinal tract to achieve antigen presentation. The intestinal and spleen samples were collected at different time intervals after immunization, and the expression of immune-related genes was detected by real-time fluorescence quantitative PCR. The results showed that VP4 recombinant L. lactis could induce complete cellular and humoral immune responses in the intestinal mucosal system, and effectively regulate the immunological effect of the spleen. The immunogenicity and the protective efficacy of the oral vaccine was evaluated by determining IgM levels and viral challenge to vaccinated fish, a significant level (P < 0.01) of antigen-specific IgM with GCRV-II neutralizing activity was able to be detected, which provided a effective protection in the challenge experiment. These results indicated that an oral probiotic vaccine with VP4 expression can provide effective protection for grass carp against GCRV-II challenge, suggesting a promising vaccine strategy for fish.

Protection conferred by an H5 DNA vaccine against highly pathogenic avian influenza in chickens: The effect of vaccination schedules.

H5 highly pathogenic avian influenza (HPAI) viruses of the Asian lineage (A/goose/Guangdong/1/96) belonging to clade 2.3.4.4 have spread worldwide through wild bird migration in two major waves: in 2014/2015 (clade 2.3.4.4c), and since 2016 up to now (clade 2.3.4.4b). Due to the increasing risk of these H5 HPAI viruses to establish and persist in the wild bird population, implementing vaccination in certain sensitive areas could be a complementary measure to the disease control strategies already applied. In this study, the efficacy of a novel DNA vaccine, encoding a H5 gene (A/gyrfalcon/Washington/41088-6/2014 strain) of clade 2.3.4.4c was evaluated in specific pathogen-free (SPF) white leghorn chickens against a homologous and heterologous H5 HPAI viruses. A single vaccination at 2 weeks of age (1 dose), and a vaccination at 2 weeks of age, boosted at 4 weeks (2 doses), with or without adjuvant were characterized. The groups that received 1 dose with or without adjuvant as well as 2 doses with adjuvant demonstrated full clinical protection and a significant or complete reduction of viral shedding against homologous challenge at 6 and 25 weeks of age. The heterologous clade 2.3.4.4b challenge of 6-week-old chickens vaccinated with 2 doses with or without adjuvant showed similar results, indicating good cross-protection induced by the DNA vaccine. Long lasting humoral immunity was observed in vaccinated chickens up to 18 or 25 weeks of age, depending on the vaccination schedule. The analysis of viral transmission after homologous challenge showed that sentinels vaccinated with 2 doses with adjuvant were fully protected against mortality with no excretion detected. This study of H5 DNA vaccine efficacy confirmed the important role that this type of so-called third-generation vaccine could play in the fight against H5 HPAI viruses.

Effects of transfluthrin-treated jute and cotton clothing against resistant and susceptible Aedes aegypti (Diptera: Culicidae) in a semifield system.

Volatile pyrethroids exert a range of both lethal and behavioral effects on mosquitoes through the passive release of insecticides into the atmosphere. We investigated the protective efficacy (PE) of transfluthrin-treated jute (TI-jute) and cotton (TI-cotton) fabrics, worn at the back of a protective black vest, against laboratory-reared pyrethroid susceptible and resistant strains of Aedes aegypti (L.) in a semifield system (SFS). Each fabric (1,029 cm2) was treated with 1.79 mg/cm2 of transfluthrin as the intervention. Human landing collections were conducted by 2 collectors seated in designated treatment and control compartments of the SFS. The trials were conducted for 41 days, with 16 days partitioned into morning and evening phases. Furthermore, we examined blood feeding behavior and fecundity of the surviving mosquitoes post-exposure. Results showed that in the morning, the PE of TI-jute (49.4%) was higher than that of TI-cotton (36.8%). TI-jute demonstrated a lower PE of 9.6% against the transfluthrin-resistant strain. Remarkably, a significantly higher number of eggs were laid by the transfluthrin-resistant mosquitoes that survived the intervention (36.5 eggs/female) compared to the control group (11.8 eggs/female). These findings suggest that TI-jute can help protect against bites and alter the life traits of Ae. aegypti. The study highlights that the timing of the intervention during the day affected the efficacy of TI-jute and TI-cotton, while sublethal exposure to transfluthrin stimulated egg production in the resistant strain. These are critical challenges that warrant attention in vector control strategies. Investigating this phenomenon in mosquito reproduction necessitates future research at a molecular level.

Molecular characterization and immune protective efficacy of 3 Eimeria tenella antigens.

Avian coccidiosis caused by Eimeria is a serious parasitic disease that poses a threat to the poultry industry. Currently, prevention and treatment mainly rely on the administration of anticoccidials and live oocyst vaccines. However, the prevalence of drug resistance and the inherent limitations of live vaccines have driven the development of novel vaccines. In this study, the surface protein (Et-SAG14), a previously annotated rhoptry protein (Eten5-B), and a gametocyte phosphoglucomutase (Et-PGM1) were characterized and the vaccine potential of the recombinant proteins were evaluated. Et-SAG14 was dispersed in the form of particles in the sporozoite and merozoite stages, whereas Et-PGM1 was distributed in the apical part of the sporozoite and merozoite stages. The previously annotated rhoptry Eten5-B was found not to be located in the rhoptry but distributed in the cytoplasm of sporozoites and merozoites. Immunization with rEten5-B significantly elevated host interferon gamma (IFN-γ) and interleukin 10 (IL-10) transcript levels and exhibited moderate anticoccidial effects with an anticoccidial index (ACI) of 161. Unexpectedly, both recombinant Et-SAG14 and Et-PGM1 immunization significantly reduced host IFN-γ and IL-10 transcription levels, and did not show protection against E. tenella challenge (ACI < 80). These results suggest that the rEten5-B protein can trigger immune protection against E. tenella and may be a potential and effective subunit vaccine for the control of coccidiosis in poultry.

Immunogenicity and protective efficacy of recombinant adenovirus expressing a novel genotype G2b PEDV spike protein in protecting newborn piglets against PEDV.

IMPORTANCE: Porcine epidemic diarrhea (PED) is a highly infectious and economically significant gastrointestinal disorder that affects pigs of all ages. Preventing and controlling PED is achieved by immunizing sows with vaccines, enabling passive piglet immunization via colostrum. The prevalence of G2b porcine epidemic diarrhea virus (PEDV) continues in China despite the use of commercial vaccines, raising questions regarding current vaccine efficacy and the need for novel vaccine development. Adenovirus serotype 5 (Ad5) has several advantages, including high transduction efficiency, a wide range of host cells, and the ability to infect cells at various stages. In this study, we expressed the immunogenic proteins of spike (S) using an Ad5 vector and generated a PED vaccine candidate by inducing significant humoral immunity. The rAd5-PEDV-S prevented PED-induced weight loss, diarrhea, and intestinal damage in piglets. This novel vaccine candidate strain possesses the potential for use in the pig breeding industry.

Comparative protective efficacy of a newly generated live recombinant thermostable highly attenuated vaccine rK148/GVII-F using a single regimen against lethal NDV GVII.1.1.

RESEARCH HIGHLIGHTS: A thermostable, safe, and effective NDV GVII recombinant vaccine was generated.Fusion gene replacement with GVII did not affect GI K148/08 virus thermostability.Strain rK148/GVII-F provided adequate protection against a lethal NDV challenge.Oropharyngeal shedding was significantly reduced on post-challenge days 5 and 7.

Immune responses and protective efficacy of American eel (Anguilla rostrata) immunized with a formalin-inactivated vaccine against Anguillid herpesvirus.

Anguillid herpesvirus 1 (AngHV), the causative agent of "mucus sloughing and hemorrhagic septicemia disease", causes serious infectious diseases in farmed eel. Among the effective prevention and control strategies, vaccination is one of the most effective approaches. However, no vaccine for AngHV is available. Our study developed a formalin-inactivated AngHV vaccine and evaluated its performance in American eels. Initially, AngHV-FJ, a strain of AngHV, was inactivated completely by 0.1 % formaldehyde, mixed with adjuvant Montanide ISA 763 A VG (763A). Then, vaccines containing different amount of antigen (3 × 106 PFU, 3 × 105 PFU, 3 × 104 PFU, 3 × 103 PFU) were immunized in each American eels. The results showed that the 3 × 105 PFU/fish was the proper dose. The inactivated AngHV vaccine was proven safe for American eels by back intramuscular injection. The results of twice immunization showed that antibody production peaked in the 8th week after the first immunization, and the antibody titer was 1:64,000. Furthermore, the immunized fishes challenged with AngHV (105 PFU/ml immersion) showed a significantly lower incidence rate (33.33 %) than the control group (95.65 %). The survival of the fish in the vaccine group (94.44 %) was significantly higher than the control group (60.87 %). The relative survival rate of the vaccinated group was 85.80 %. Also, vaccine group tissue collected at 7th d post-challenge showed reduced tissue damage and a lower virus load than the control group. The expression of cytokines of IL-1ß, IFN-α, IFN-γ, Mx1, RIG-1, and IRF-3, were significantly lower in the vaccine group than the control group at the 7th and 14th d post-challenge. Overall, the formalin-inactivated AngHV vaccine was safe and had immune protective effects against AngHV infection.