Characterization Of Antigens Research Articles

Identification of linear B cell epitopes on the E146L protein of African swine fever virus with monoclonal antibodies.

The outbreak and spread of African swine fever virus (ASFV) have caused considerable economic losses to the pig industry worldwide. Currently, to promote the development of effective ASF vaccines, especially subunit vaccines, more antigenic protein targets are urgently needed. In this work, six transmembrane proteins (I329L, E146L, C257L, EP153R, I177L, and F165R) were expressed in mammalian cell lines and screened with pig anti-ASFV serum. It was found that the E146L protein was an immunodominant protein antigen among the six selected proteins. Moreover, the E146L protein induced antibody responses in all immunized pigs. To gain insight into the antigenic characteristics of the E146L protein, three monoclonal antibodies (mAbs; 12H12, 15G1, and 15H10) were generated by immunizing BALB/c mice with the purified E146L protein. The epitopes of the mAbs were further finely mapped through a peptide fusion protein expression strategy. Finally, the epitopes of the mAbs were identified as 48PDESSIAYMRFRN61 of the mAb 12H12, 138TLTGLQRII146 of the mAb 15G1, and 30GWSPFKYSKGNT41 of the mAb 15H10. Furthermore, the epitope of mAb 15H10 was validated as the immunodominant epitope with ASFV-infected pig sera. The chemically synthesized mAb 15H10 epitope peptide (EP1) exhibited the most extensive immunoreactivity with artificially or naturally ASFV-infected pig sera. The epitope 15H10 is located on the surface of the E146L protein and is highly conserved. These findings provide insight into the structure and function of the E146L protein of ASFV.

2018-2019 human seasonal H3N2 influenza A virus spillovers into swine with demonstrated virus transmission in pigs were not sustained in the pig population.

Human seasonal H3 clade 3C3a influenza A viruses (IAV) were detected four times in U.S. pigs from commercial swine farms in Michigan, Illinois, and Virginia in 2019. To evaluate the relative risk of this spillover to the pig population, whole genome sequencing and phylogenetic characterization were conducted, and the results revealed that all eight viral gene segments were closely related to 2018-2019 H3N2 human seasonal IAV. Next, a series of in vitro viral kinetics, receptor binding, and antigenic characterization studies were performed using a representative A/swine/Virginia/A02478738/2018(H3N2) (SW/VA/19) isolate. Viral replication kinetic studies of SW/VA/19 demonstrated less efficient replication curves than all 10 swine H3N2 viruses tested but higher than three human H3N2 strains. Serial passaging experiments of SW/VA/19 in swine cells did not increase virus replication, but changes at HA amino acid positions 9 and 159 occurred. In swine transmission studies, wild-type SW/VA/19 was shed in nasal secretions and transmitted to all indirect contact pigs, whereas the human seasonal strain A/Switzerland/9715293/2013(H3N2) from the same 3C3a clade failed to transmit. SW/VA/19 induced minimal macroscopic and microscopic lung lesions. Collectively, these findings demonstrate that these human seasonal H3N2 3C3a-like viruses did not require reassortment with endemic swine IAV gene segments for virus shedding and transmission in pigs. Limited detections in the U.S. pig population in the subsequent period of time suggest a yet-unknown restriction factor likely limiting the spread of these viruses in the U.S. pig population.IMPORTANCEInterspecies human-to-swine IAV transmission occurs globally and contributes to increased IAV diversity in pig populations. We present data that a swine isolate from a 2018-2019 human-to-swine transmission event was shed for multiple days in challenged and contact pigs. By characterizing this introduction through bioinformatic, molecular, and animal experimental approaches, these findings better inform animal health practices and vaccine decision-making. Since wholly human seasonal H3N2 viruses in the United States were not previously identified as being transmissible in pigs (i.e., reverse zoonosis), these findings reveal that the interspecies barriers for transmission to pigs may not require significant changes to all human seasonal H3N2, although additional changes may be required for sustained transmission in swine populations.

Genetic analysis of a blood donor with combined FUT1 and ABO dual blood group gene variants resulting in para-Bombay and A2 subtype blood types and a literature review

To investigate the serological and molecular genetic characteristics of a voluntary blood donor with combined FUT1 and ABO blood group gene variants causing para-Bombay and A2 subtype, and to review relevant literature on para-Bombay blood types carrying alleles such as FUT101W.37 and FUT101W.23. A blood donor with para-Bombay and A2 subtype who participated in voluntary blood donation at the Dongguan Blood Center in August 2023 was selected as the study subject. Serological tests were performed to identify the ABO blood group, Lewis blood group antigens, and unexpected serum antibodies in the donor. Adsorption-elution test was conducted to detect trace antibodies in the blood donor's plasma to trace the A, B and H antigens on the red blood cell surface. Sanger sequencing was carried out to analyze the sequences of the FUT1 and ABO genes. Using keywords such as "para-Bombay" "FUT1*01W.37" and "FUT1*01W.23" both in Chinese and English, relevant literature on para-Bombay blood type subjects carrying FUT1*01W.37 and FUT1*01W.23 alleles was retrieved from the CNKI, Wanfang Data Knowledge Service Platform, and PubMed databases, and the retrieval time was set as from the establishment of database to December 2022. This study has been approved by the Ethics Committee of Dongguan Blood Center (No. 2022005), and informed consent of blood donation was obtained from the blood donor. Serological testing of the blood donor revealed inconsistent results between forward and reverse ABO blood typing, negative H antigen on the red blood cell surface, Le(a-b+) secretor type for Lewis blood group, and unexpected anti-H antibodies in the plasma, indicating a suspected para-Bombay type. Absorption-elution test suggested the blood type of the blood donor to be para-Bombay and A subtype. Sanger sequencing showed that the donor has harbored homozygous FUT1*(c.35T+c.803A)/(c.35T+c.803A) variant, with the FUT1*(c.35T+c.803A) allele containing a dual nucleotide variant unrecorded by the International Society of Blood Transfusion (ISBT) FUT1 gene variant database, which was similar to the weakly functional allele of FUT101W. 37(c.803G>A) as recorded by the ISBT database. The ABO genotype was heterozygous ABOA2.05/O.01.02. Combining the results of serological and genetic testing, the blood type of the blood donor was determined to be para-Bombay and A2 subtypes. Literature review has identified a pregnant women from Qingdao carrying the FUT1*01W.37 allele and 2 individuals carrying a heterozygous FUT1*01W.23 allele. This study has discovered a blood donor with coexisting para-Bombay and ABO subtype blood groups. Based on the characteristics of red blood cell surface antigens, the FUT1*01W.37 as classified as an FUT1 null allele.

Application of surface Plasmon resonance imaging in the high-throughput detection of influenza virus.

To evaluate the application effect of SPRi monoclonal antibody (mAb) chip in the detection of influenza virus antigen in complex mixtures. A total of 115 strains of mAbs against different subtypes (H1N1, H5N1, A1, A3, B, H7N9, H9N2, and H3N2) of influenza virus were prepared. The chip of mAbs against influenza virus was prepared by surface plasmonic resonance imaging (SPRi) technology, which was used for the detection of influenza virus supernatant, and compared with the traditional antigen capture ELISA method. Comparative studies have shown that traditional antigen capture ELISA methods have a higher sensitivity (86.8% (46/53) vs. 46.5% (46/99); z = 4.84, P < .001), while the SPRi chip methods present a significantly higher specificity (56.3% (9/16) vs. 14.5% (9/62); z = 3.54, P < .001). The SPRi chip detection method for influenza virus antibodies can well reflect the specific binding characteristics of influenza virus antigens and antibodies. The SPRi mAb chip can be used for the detection of specific pathogenic microorganisms or viral proteins in complex mixtures such as influenza virus supernatant. It has significant advantages of label free, real-time, high-throughput, and good specificity, and can play an important role in disease diagnosis and infectious disease prevention and control.

Triton X-100-treated virus-based ELLA demonstrates discordant antigenic evolution of influenza B virus hemagglutinin and neuraminidase.

Neuraminidase (NA)-specific antibodies have been associated with protection against influenza and thus NA is considered a promising target for next-generation vaccines against influenza A (IAV) and B viruses (IBV). NA inhibition (NI) by antibodies is typically assessed using an enzyme-linked lectin assay (ELLA). However, ELLA can be confounded by anti-hemagglutinin (anti-HA) antibodies that block NA by steric hindrance (termed HA interference). Although strategies have been employed to overcome HA interference for IAV, similar approaches have not been assessed for IBV. We found that HA interference is common in ELLA using IBV, rendering the technique unreliable. Anti-HA antibodies were not completely depleted from sera by HA-expressing cell lines, and this approach was of limited utility. In contrast, we find that treatment of virions with Triton X-100, but not Tween-20 or ether, efficiently separates the HA and NA components and overcomes interference caused by anti-HA antibodies. We also characterize a panel of recombinant IBV NA proteins that further validated the results from Triton X-100-treated virus-based ELLA. Using these reagents and assays, we demonstrate discordant antigenic evolution between IBV NA and HA over the last 80 years. This optimized ELLA protocol will facilitate further in-depth serological surveys of IBV immunity as well as antigenic characterization of the IBV NA on a larger scale.IMPORTANCEInfluenza B viruses (IBVs) contribute to annual epidemics and may cause severe disease, especially in children. Consequently, several approaches are being explored to improve vaccine efficacy, including the addition of neuraminidase (NA). Antigen selection and assessment of serological responses will require a reliable serological assay to specifically quantify NA inhibition (NI). Although such assays have been assessed for influenza A viruses (IAVs), this has not been done of influenza B viruses. Our study identifies a readily applicable strategy to measure the inhibitory activity of neuraminidase-specific antibodies against influenza B virus without interference from anti-hemagglutinin (anti-HA) antibodies. This will aid broader serological assessment of influenza B virus-specific antibodies and antigenic characterization of the influenza B virus neuraminidase.

Insights into Genetic and Antigenic Characteristics of Influenza A(H1N1)pdm09 Viruses Circulating in Sicily During the Surveillance Season 2023-2024: The Potential Effect on the Seasonal Vaccine Effectiveness.

After disruption in the influenza circulation due to the emergence of SARS-CoV-2, the intensity of seasonal outbreaks has returned to the pre-pandemic levels. This study aimed to evaluate the evolution and variability of whole-genome sequences of A(H1N1)pdm09, the predominant influenza virus in Sicily (Italy) during the season 2023-2024. The potential vaccine efficacy was calculated using the pepitope model based on amino acid changes in the dominant epitope of hemagglutinin. The HA gene sequences showed several amino acid substitutions, some of which were within the major antigenic sites. The phylogenetic analysis showed that Sicilian strains grouped into two main genetic clades (6B.1A.5a.2a.1 and 6B.1A.5a.2a) and several subclades. Notably, about 40% of sequences partially drifted from the WHO-recommended vaccine strain A/Victoria/4897/2022 for the Northern Hemisphere. These sequences mostly belonged to the subclades C.1.8 and C.1.9 and harboured the amino acid mutations responsible for the modest predicted vaccine efficacy (E = 38.12% of 53%, pepitope = 0) against these viruses. Amino acid substitutions in other gene segments were also found. Since influenza viruses are constantly evolving, genomic surveillance is crucial in monitoring their molecular evolution and the occurrence of genetic and antigenic changes, and, thus, their potential impact on vaccine efficacy.

Ethnic diversity in Chilean blood groups: A comprehensive analysis of genotypes, phenotypes, alleles and the immunogenic potential of antigens in northern, southern and central regions.

The available information on blood groups in the Chilean population is derived from studies on aboriginal cohorts and routine serological test results. The purpose of this study is to conduct a comprehensive analysis of genotypes, phenotypes and blood group alleles in donors from northern, central and southern Chile using molecular methods. Overall, 850 samples from donors in northern, central and southern Chile were genotyped. Allelic, genotypic and antigenic frequencies were calculated and compared among regions. Of these, 602 samples were analysed by haemagglutination, and discrepancies found between phenotypes and genotypes were investigated. The immunogenic potential of antigens was calculated by the Giblett equation, using the antigenic frequencies of donors from Santiago and the alloantibody frequencies of patients from the same region. Alleles of low prevalence, variant alleles and those responsible for the absence of high-prevalence antigens were found. Significant differences were observed between the antigenic frequencies of the three regions. Discrepancies between serologic and molecular results were mostly attributed to the molecular background affecting antigen expression. In the calculation of the immunogenic potential of antigens, the highest value was attributed to the Dia antigen. These findings represent the first molecular characterization of blood group antigens in Chileans. Our results highlight the necessity of using molecular tools to explore the genotypes underlying variant phenotypes, low-frequency antigens and antigens lacking specific antisera that cannot be detected by haemagglutination. Additionally, they emphasize the importance of understanding the distribution of blood groups among different populations.

Cats: The New Challenge for Rabies Control in the State of Yucatan, Mexico.

The growing population in Yucatan has led to the expansion of construction in the Mayan jungle for tourist spaces, residential areas, and agriculture. Recently, rabies cases in cats (Felis catus) have increased in the state. This study aimed to perform antigenic and genetic characterization of the rabies viruses in felines and to present the spatial distribution and environmental features of the areas where these cases were reported. The ArcGIS software and R were employed to generate maps depicting the geographic locations of rabies cases in cats. A total of nine feline rabies cases occurred during the period 2003-2022. Three antigenic variants were detected: dog-related RVV1 (n = 1); vampire bat variant RVV3 (n = 1); and the canine-originated atypical variant (n = 7). Cases reported in Merida (n = 4) and Muna (n = 4) were localized to urban areas, while Cuncunul (n = 1) was rural. This study highlights the concerning resurgence of rabies infections in cats, emphasizing the looming threat of its reintroduction in dogs should vaccination rates diminish. The genetic affinity between the atypical variant and the canine virus underscores the urgent need for vigilance in maintaining high vaccination coverage across all susceptible species.

Generation and epitope mapping of novel neutralizing monoclonal antibodies against glycoprotein E2 of CSFV

Classical swine fever virus (CSFV) is a highly contagious and economically important pathogen threatening pig industry worldwide, the envelope glycoprotein E2 of CSFV is the dominant antigen inducing strong antiviral neutralizing immunity. In this study, 7 monoclonal antibodies (mAbs) with neutralizing potency were generated using E2 protein of CSFV Shimen strain (SM) expressed by eukaryotic cells. Their reactivity with 116 CSFV strains in cell cultures and E2 proteins of 10 subgenotypes in western blots showed different CSFV spectrums they recognized. Of them, three (HCL-001, HCL-005 and HCL-010) reacted with all CSFV subgenotypes, while HCL-014 and HCL-002 reacted with most CSFV strains, except for some variants in genotype 2.3. In contrast, mAb HCL-009 reacted only with a few subgenotype 1.1 strains including SM, field strains and some vaccine strains. Interestingly, mAb HCL-018 reacted only with SM and field subgenotype 1.1 strains, not with any vaccine strains. Further epitope mapping using chimeric and site-directed mutated E2 proteins showed that HCL-001, HCL-005 and HCL-010 recognized a conservative epitope motif 143SPT145,L147, and HCL-002 recognized a conformational epitope with key aa motifs of 95GDD97,157RX(D/E)K(R)XFXXR164. HCL-014 recognized a new conservative epitope with key aa motifs of 41D,58XNVVXRR64. HCL-009 and HCL-018 recognized the epitope with key aa motifs of 36D,40ND41,45KXI47 and 69LHXGXLLT76, respectively. Taken together, present study has provided not only new insights into the antigenic structure of E2 protein, but also key reagents for antigenic characterization of CSFV strains and development of antibody assay for evaluation of the vaccination efficacy.

Genetic and antigenic characterization of influenza A(H3N2) virus after 13 consecutive years of influenza surveillance in Senegal, 2010-2022.

Despite decades of influenza surveillance in many African countries, little is known about the evolutionary dynamics of seasonal influenza viruses. This study aimed to characterize the epidemiological, genetic and antigenic profiles of A/H3N2 viruses in Senegal from 2010 to 2022. A/H3N2 infection was confirmed using reverse transcription-polymerase chain reaction. Subsequently, a representative of A/H3N2 isolates was selected for genome sequencing. Predicted vaccine efficacy was measured using the Pepitope model. During the study period, 22638 samples were tested and influenza was detected in 31.8%, among which type A was confirmed in 78.1%. Of the Influenza A cases, the H3N2 subtype was detected in 29.8%, peaking at expected times during the rainy season. Genome sequencing of 123A/H3N2 isolates yielded 24 complete and 99 partial genomic sequences. Phylogenetic analysis revealed the circulation of multiple clades of A/H3N2 in Senegal, including 2a.3, 3C.2 and 3C.3a. A/H3N2 isolates were mainly susceptible to the influenza antiviral drugs oseltamivir and zanamivir, but the primary adamantine-resistance marker, S31N was encountered in all isolates. At least nine potential N-linked glycosylation sites were predicted among A/H3N2 strains, six of which (at positions 24, 38, 79, 181, 262 and 301) remains conserved among all isolates. Antigenic distances between circulating strains and vaccine viruses indicated varying vaccine efficacies, from suboptimal to moderate protection. The findings emphasize the need to enhance local genomic and antigenic surveillance and further research on influenza epidemiology and genetic evolution in sub-Saharan Africa.

Immunogenicity and Safety of Omicron-Containing Multivalent COVID-19 Vaccines in Unvaccinated and Previously Vaccinated Adults.

The SARS-CoV-2 evolution trajectory remains uncertain, and the antigenic characteristics of future variants are highly unpredictable. We report the immunogenicity and safety of multivalent COVID-19 vaccines, SCTV01E and SCTV01E-1, against Omicron BA.5. This phase 2 trial randomized 400 adults into two cohorts, 160 unvaccinated (3 doses) and 240 previously vaccinated (2 doses) individuals to receive 30 µg SCTV01E-1 or 30 µg SCTV01E (1:1) between 4 November and 28 November 2022. Among the unvaccinated cohort, day 42 geometric mean fold rises (GMFRs) of neutralizing antibodies (nAb) against Omicron BA.5 were reported to be 12.8× and 20.5× over day 0 for SCTV01E-1 and SCTV01E, respectively. On day 178, both vaccines increased geometric mean titers (GMTs) of nAb against BA.5 following the booster dose compared to pre-booster levels on D150. Similar frequencies of solicited [6.2% (5/81) and 7.6% (6/79)] and unsolicited [11.1% (9/81) and 10.1% (8/79)] adverse events (AEs) were reported in SCTV01E-1 and SCTV01E groups, respectively. Grade 3 or more AEs were < 2% in both vaccine groups [SCTV01E-1: 1.2% (1/81), SCTV01E: 1.3% (1/79)]. In the previously vaccinated cohort, similar GMFRs were reported on day 28 (SCTV01E-1: 9.4× and SCTV01E: 8.7×) over baseline (D0). On day 148, both vaccines showed increased nAb levels with similar GMFRs over D120. Comparable incidences of solicited [13.2% (16/121) and 10.9% (13/119)] and unsolicited [17.4% (21/121) and 10.9% (13/119)] AEs were reported in SCTV01E-1 and SCTV01E groups, respectively. Numerically identical ≥ grade 3 AEs [SCTV01E-1: 1.7% (2/121) and SCTV01E: 1.7% (2/119)] were reported. This trial demonstrates the effectiveness of updated multivalent vaccines with acceptable safety profiles.

Clinical Value of Dual Tracer PET Imaging With 68Ga-PSMA and 18F-FDG in Patients With Metastatic Prostate Cancer

In this study, we retrospectively analyzed the imaging characteristics of dual-tracer 68Ga-prostate specific membrane antigen (PSMA) and 18F-flurodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in metastatic prostate cancer (mPCa) patients. We analyzed the uptake modes of the dual tracers, explored clinical pathological parameters affecting the 18F-FDG uptake in the lesions, and evaluated their prognostic implications for prostate specific antigen progression-free survival (PSA-PFS). A total of 41 mPCa patients who underwent dual-tracer PET/CT (68Ga-PSMA and 18F-FDG) scans between September 2021 and January 2024 were retrospectively enrolled. One patient had negative uptake of both PSMA and FDG. According to the uptake patterns of the 2 tracers, the other patients, 40 in total, were categorized in 2 groups, including group A consisting of 33 cases who showed PSMA and FDG dual and those who showed FDG only avidity, and group B consisting of 7 cases who showed PSMA avidity only. Comparative analyses of clinical pathological characteristics between group A and group B were conducted. The relationship between various parameters and PSA-PFS was analyzed by the Kaplan-Meier method. A total of 26 patients (63.4%) were diagnosed with metastatic castration-resistant prostate cancer (mCRPC), and 38 cases (92.7%) had a Gleason score of 8-9. Bone metastasis, the predominant type of distant metastasis, occurred in 36 cases (87.8%). The skeletal and distant lymph node metastases mostly showed a dual positive uptake pattern for both PSMA and FDG (85.7% [24/28] and 81.8% [9/11]). 37.5% (3/8) of the metastases to organs showed FDG only positive uptake pattern. The serum levels of prostate specific antigen (PSA) in group A were significantly higher than those in group B (P=0.013). A total of 13 patients of special pathological classification (intraductal carcinoma and neuroendocrine differentiation) were all found to be in group A. Among the 41 cases, 16 were lost to follow-up. Of the 25 patients who completed follow-up, 9 patients, with a median PSA value of 104 ng/mL, experienced PSA progression, while the 16 other patients, with a median PSA of 0.34 ng/mL, did not incur any PSA progression. There was significant difference in the median PSA between patients showing PSA progression and those who did not show PSA progression (P<0.001). Kaplan-Meier survival analysis revealed that the median PSA-PFS of patients of specific pathological classifications was 7 months, which was shorter than the 16 months of the patients with typical prostate cancer, with the difference between the two groups being statistically meaningful (P=0.043). The median PSA-PFS for group A was 30 months. With more than half of the patients in the group not experiencing any PSA progression, group B did not reach the median PSA-PFS (P=0.645). Dual-tracer PET/CT imaging with 68Ga-PSMA and 18F-FDG commonly exhibits avidity for both tracers in mPCa. Serum PSA level is a reliable biomarker for predicting FDG-positive lesions. mPCa presented with intraductal carcinoma and neuroendocrine differentiation tends to exhibit FDG avidity and is more susceptible to PSA progression.

Preliminary In silico Analysis of Adenylate Kinase 1 (ADK1) of Echinococcus granulosus as a Candidate for Vaccination against Cystic Echinococcosis

Background: A neglected zoonosis, Cystic Echinococcosis (CE), is most common in developing nations worldwide. Vaccination is, therefore, helpful in preventing the disease. Objective: Predicting the main biochemical properties of E. granulosus Adenylate Kinase 1 (ADK1) and its possible B-cell and T-cell-binding epitopes as a valuable candidate for immunization was the goal of the current study. Methods: Predictions were made to determine biochemical, antigenic, structural, and subcellular characteristics, along with the immunogenic epitopes, using several online servers. Results: The extracellular 22 KDa protein had no allergenicity, while it possessed hydrophilicity (GRAVY: -0.286), stability (instability: 17.48), tolerance to a wide range of temperatures (aliphatic: 93.45), and 17 post-translational modification sites. The secondary structure mostly comprised helices and random coils and the 3D model was generated using Robetta server (confidence: 0.88). Common B-cell epitopes were discovered by three servers and screened for antigenic, allergenic, and solubility traits. Moreover, MHC-associated epitopes for mice and humans were predicted in E. granulosus ADK1 with subsequent screening. Conclusion: This work offers a foundation for further investigation on designing an effective vaccination against CE. Further empirical research study with the examined protein solely or combined with other antigens is needed.

Comprehensive bioinformatics assessments of the ROP34 of Toxoplasma gondii to approach vaccine candidates

IntroductionRhoptries proteins (ROPs) are crucial throughout different stages of the Toxoplasma gondii (T. gondii) lifecycle, playing key roles in both the invasion of host cells and their subsequent survival. ROP34 is particularly noteworthy as it significantly influences host gene expression and aids in the transition from the tachyzoite to the bradyzoite form.Materials and methodsThis research utilized various bioinformatics tools to assess physico-chemical properties, allergenic and antigenic characteristics, sites for post-translational modifications (PTMs) and protein's secondary and three-dimensional structures of the ROP34 protein. Furthermore, the study identified potential B-cell, MHC-binding, and cytotoxic T-lymphocyte (CTL) epitopes within the ROP34 sequence.ResultsThe ROP34 peptide comprised 553 amino acid residues, with a calculated average molecular weight (MW) of 61.60149 kDa, an aliphatic index of 73.98, and a GRAVY score of − 0.554. The antigenicity of the multi-epitope peptide was estimated to be 0.526563 and 0.6025 by the ANTIGENpro and VaxiJen servers, respectively, suggesting ROP34 as an immunogenic protein with no allergenic potential. Secondary structure analysis revealed a composition of 52.80% random coil, 36.17% alpha helix, and 11.03% extended strand. The Ramachandran plot for the refined model depicted that 97.46% of the residues were situated in the favored region.ConclusionThis in silico research serves as a foundation for designing effective immunization tactics to target toxoplasmosis. The present article lays the groundwork for future studies and offers perspectives for the advancement of an appropriate toxoplasmosis vaccine.Graphical

Rational design of a multi-epitope vaccine against heartland virus (HRTV) using immune-informatics, molecular docking and dynamics approaches

Heartland virus (HRTV) is a single-stranded negative-sense RNA virus that infects human beings. Because there are no antiviral medications available to treat HRTV infection, supportive care management is used in cases of severe disease. Therefore, it has spurred research into developing a multi-epitope vaccine capable of providing effective protection against HRTV infection. A multi-epitope vaccine was created using a combination of immuno-informatics, molecular docking and molecular dynamics simulation in this investigation. The HRTV proteome was utilized to predict B-cell, T-cell (HTL and CTL), and IFN-epitopes. Following prediction, highly antigenic, non-allergenic and immunogenic epitopes were chosen, including 6 CTL, 8 HTL, and 5 LBL epitopes that were connected to the final peptide by AAY, GPGPG, and KK linkers, respectively. An adjuvant was introduced to the vaccine's N-terminal through the EAAAK linker to increase its immunogenicity. Following the inclusion of linkers and adjuvant, the final construct has 359 amino acids. The presence of B-cell and IFN-γ-epitopes validates the construct's acquired humoral and cell-mediated immune responses. To ensure the vaccine's safety and immunogenicity profile, its allergenicity, antigenicity, and various physicochemical characteristics were assessed. Docking was used to assess the binding affinity and molecular interaction between the vaccination and TLR-3. In silico cloning was used to confirm the construct's validity and expression efficiency. The results of these computer assays demonstrated that the designed vaccine is highly promising in terms of developing protective immunity against HRTV; nevertheless, additional in vivo and in vitro investigations are required to validate its true immune-protective efficiency.

A quadri-fluorescence SARS-CoV-2 pseudovirus system for efficient antigenic characterization of multiple circulating variants

The ongoing co-circulation of multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains necessitates advanced methods such as high-throughput multiplex pseudovirus systems for evaluating immune responses to different variants, crucial for developing updated vaccines and neutralizing antibodies (nAbs). We have developed a quadri-fluorescence (qFluo) pseudovirus platform by four fluorescent reporters with different spectra, allowing simultaneous measurement of the nAbs against four variants in a single test. qFluo shows high concordance with the classical single-reporter assay when testing monoclonal antibodies and human plasma. Utilizing qFluo, we assessed the immunogenicities of the spike of BA.5, BQ.1.1, XBB.1.5, and CH.1.1 in hamsters. An analysis of cross-neutralization against 51 variants demonstrated superior protective immunity from XBB.1.5, especially against prevalent strains such as "FLip" and JN.1, compared to BA.5. Our finding partially fills the knowledge gap concerning the immunogenic efficacy of the XBB.1.5 vaccine against current dominant variants, being instrumental in vaccine-strain decisions and insight into the evolutionary path of SARS-CoV-2.

Antigenic and molecular characterisation of viruses responsible for outbreaks of equine influenza (2021–2024)

Antigenic and molecular characterisation of viruses responsible for outbreaks of equine influenza (2021–2024)

Characterization of Tenacibaculum maritimum isolated from diseased salmonids farmed in Chile reveals high serological and genetic heterogeneity.

The diversity of Tenacibaculum maritimum in Chile remains poorly understood, particularly in terms of antigenic and genetic diversity. This information is crucial for the future development of a vaccine against tenacibaculosis and would increase understanding of this important fish pathogen. With this aim, the biochemical, antigenic, and genetic characteristics were analysed for 14 T. maritimum isolates, recovered from diseased Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) farmed in Chile between 1998 and 2022. Biochemical analysis showed a homogeneity among all the Chilean T. maritimum isolates and all four other strains included for comparison purposes. Serological characterization using dot-blot assaying revealed antigenic heterogeneity with the use of unabsorbed antisera. The majority of isolates showed cross-reactions, identifying three main serological patterns. When the PCR-based serotyping scheme was performed, the existence of antigenic heterogeneity was confirmed. Four Atlantic salmon isolates were 4-0; and most isolates, including the rainbow trout isolate, were 3-1 (n = 9). A turbot (Scophthalmus maximus) isolate was 1-0. Using an existing Multilocus Sequence Typing system, two newly identified sequence types (ST193 and ST198) in the database were detected. ST193 encompassed nine isolates obtained from Atlantic salmon and rainbow trout, while ST198 regrouped four isolates, all retrieved from diseased Atlantic salmon in 2022. These findings highlight significant antigenic and genetic diversity among the Chilean isolates. This information is useful for epizootiology and the selection of suitable candidate strain(s) for vaccine development against tenacibaculosis caused by T. maritimum in Chilean salmon farming.

Phylogenetic analyses and antigenic characterization of foot-and-mouth disease virus PanAsia lineage circulating in China between 1999 and 2023

Foot-and-mouth disease (FMD) is one of the most important transboundary animal diseases caused by foot-and-mouth disease virus (FMDV), leading to significant economic losses worldwide. The first report of PanAsia lineage of FMDV in China was in 1999. Since 2011, 18 outbreaks attributed to PanAsia lineage viruses have been reported across 7 provinces or municipality in China. Phylogenetic analysis indicated that these PanAsia strains were clustered into three distinct clades (clade 1, clade 2, and clade 3), with nucleotide homology ranging from 91.4% to 100%. The outbreaks of FMD caused by clade 1 strains occurred around 1999 when this lineage was prevalent globally. Clade 2 strains dominated from 2011 to 2013, while clade 3 strains were prevalent during 2018–2019, sharing only 93% homology with clade 2 strains and 91% with clade 1 strains. Tracing analysis showed that these outbreaks represented 3 distinct introductions of PanAsia viruses into China. Virus neutralization tests (VNT) have demonstrated that current commercial vaccines are effective to protect susceptible animals against these strains (r1 ​> ​0.3). However, the growing demand for livestock has promoted animal movement and encouraged the exchange of products, services, and materials between countries, thereby heightening the risk of exotic strain incursions. Therefore, it is imperative to reinforce border controls and limit animal movements among various Asian countries continually to reduce the risk of new transboundary diseases, such as FMD incursion. Additionally, PanAsia-2 strains need to be taken seriously to prevent its incursions, and the relevant vaccines against PanAsia-2 strains need to be stockpiled in preparation for any possible incursion.

Genetic and antigenic characterization of two diarrhoeicdominant rotavirus A genotypes G3P[12] and G14P[12] circulating in the global equine population.

Equine rotavirus species A (ERVA) G3P[12] and G14P[12] are two dominant genotypes that cause foal diarrhoea with a significant economic impact on the global equine industry. ERVA can also serve as a source of novel (equine-like) rotavirus species A (RVA) reassortants with zoonotic potential as those identified previously in 2013-2019 when equine G3-like RVA was responsible for worldwide outbreaks of severe gastroenteritis and hospitalizations in children. One hurdle to ERVA research is that the standard cell culture system optimized for human rotavirus replication is not efficient for isolating ERVA. Here, using an engineered cell line defective in antiviral innate immunity, we showed that both equine G3P[12] and G14P[12] strains can be rapidly isolated from diarrhoeic foals. The genome sequence analysis revealed that both G3P[12] and G14P[12] strains share the identical genotypic constellation except for VP7 and VP6 segments in which G3P[12] possessed VP7 of genotype G3 and VP6 of genotype I6 and G14P[12] had the combination of VP7 of genotype G14 and VP6 of genotype I2. Further characterization demonstrated that two ERVA genotypes have a limited cross-neutralization. The lack of an in vitro broad cross-protection between both genotypes supported the increased recent diarrhoea outbreaks due to equine G14P[12] in foals born to dams immunized with the inactivated monovalent equine G3P[12] vaccine. Finally, using the structural modelling approach, we provided the genetic basis of the antigenic divergence between ERVA G3P[12] and G14P[12] strains. The results of this study will provide a framework for further investigation of infection biology, pathogenesis and cross-protection of equine rotaviruses.