The first report of porcine parvovirus 7 (PPV7) in Colombia demonstrates the presence of variants associated with modifications at the level of the VP2-capsid protein

There are a wide variety of porcine parvoviruses (PPVs) referred to as PPV1 to PPV7. The latter was discovered in 2016 and later reported in some countries in America, Asia, and Europe. PPV7 as a pathogenic agent or coinfection with other pathogens causing disease has not yet been determined. In the present study, we report the identification of PPV7 for the first time in Colombia, where it was found retrospectively since 2015 in 40% of the provinces that make up the country (13/32), and the virus was ratified for 2018 in 4/5 provinces evaluated. Additionally, partial sequencing (nucleotides 380 to 4000) was performed of four Colombian strains completely covering the VP2 and NS1 viral genes. A sequence identity greater than 99% was found when comparing them with reference strains from the USA and China. In three of the four Colombian strains, an insertion of 15 nucleotides (five amino acids) was found in the PPV7-VP2 capsid protein (540–5554 nt; 180–184 aa). Based on this insertion, the VP2 phylogenetic analysis exhibited two well-differentiated evolutionarily related groups. To evaluate the impact of this insertion on the structure of the PPV7-VP2 capsid protein, the secondary structure of two different Colombian strains was predicted, and it was determined that the insertion is located in the coil region and not involved in significant changes in the structure of the protein. The 3D structure of the PPV7-VP2 capsid protein was determined by threading and homology modeling, and it was shown that the insertion did not imply a change in the shape of the protein. Additionally, it was determined that the insertion is not involved in suppressing a potential B cell epitope, although the increase in length of the epitope could affect the interaction with molecules that allow a specific immune response.

Prediction of Epitope Peptides for PTK Gene of Acinetobacter baumannii

Background: Acinetobacter baumannii is a gramnegative bacilli acquiring both intrinsic and adaptive patterns of multi drug resistance and virulence. Immune-informatics approach holds promise to detect putative epitope peptides from vital virulence factors which can be further synthesized and evaluated for their immunological response. Aim: The aim of the study was to predict the immuno-dominant peptides from the ptk gene of A. baumannii. Materials and Methods: Protein retrieval of the Ptk gene using CELLO V.2.5 was done with the evaluation of antigenicity and allergenicity of the predicted epitopes, using Vaxijen V2.0 server and AlgPred servers. Epitope structure prediction and validation by using RAMPAGE revealed the homology peptides. Molecular Docking of epitopes with HLA-alleles using ClusterPro server, and further identification of B cell epitope was performed by using Kolaskar and Tonganokar antigenicity method. Results: A total of 20 epitopes were predicted and 18 peptides were chosen based on antigenicity and stability analysis prediction. The structure predictions were carried out using pepfold server and based on Ramachandran plot analysis 10 epitopes were taken for further analysis. Conclusion: The present finding has detected and evaluated the desirable epitope as LFFSLIAQW using an immune-informatic approach. However, it needs further experimental validation for its immunological response using standard in-vitro studies.

Mapping Sequential IgE-Binding Epitopes on Major and Minor Egg Allergens

<b><i>Introduction:</i></b> Molecular studies of hen’s egg allergens help define allergic phenotypes, with IgE to sequential (linear) epitopes on the ovomucoid (OVM) protein associated with a persistent disease. Epitope profiles of other egg allergens are largely unknown. The objective of this study was to construct an epitope library spanning across 7 allergens and further evaluate sequential epitope-specific (<i>ses-</i>)IgE and <i>ses-</i>IgG₄ among baked-egg reactive or tolerant children. <b><i>Methods:</i></b> A Bead-Based Epitope Assay was used to identify informative IgE epitopes from 15-mer overlapping peptides covering the entire OVM and ovalbumin (OVA) proteins in 38 egg allergic children. An amalgamation of 12 B-cell epitope prediction tools was developed using experimentally identified epitopes. This ensemble was used to predict epitopes from ovotransferrin, lysozyme, serum albumin, vitellogenin-II fragment, and vitellogenin-1 precursor. <i>Ses-</i>IgE and <i>ses-</i>IgG₄ repertoires of 135 egg allergic children (82 reactive to baked-egg, the remaining 52 tolerant), 46 atopic controls, and 11 healthy subjects were compared. <b><i>Results:</i></b> 183 peptides from OVM and OVA were screened and used to create an aggregate algorithm, improving predictions of 12 individual tools. A final library of 65 sequential epitopes from 7 proteins was constructed. Egg allergic children had higher <i>ses-</i>IgE and lower <i>ses-</i>IgG₄ to predominantly OVM epitopes than both atopic and healthy controls. Baked-egg reactive children had similar <i>ses-</i>IgG₄ but greater <i>ses-</i>IgE than tolerant group. A combination of OVA-sIgE with <i>ses-</i>IgEs to OVM-023 and OVA-028 was the best predictor of reactive phenotype. <b><i>Conclusion:</i></b> We have created a comprehensive epitope library and showed that <i>ses-</i>IgE is a potential biomarker of baked-egg reactivity.

Identification of a B-Cell Epitope in the VP3 Protein of Senecavirus A

Senecavirus A (SVA) is a member of the genus Senecavirus of the family Picornaviridae. SVA-associated vesicular disease (SAVD) outbreaks have been extensively reported since 2014–2015. Characteristic symptoms include vesicular lesions on the snout and feet as well as lameness in adult pigs and even death in piglets. The capsid protein VP3, a structural protein of SVA, is involved in viral replication and genome packaging. Here, we developed and characterized a mouse monoclonal antibody (mAb) 3E9 against VP3. A motif 192GWFSLHKLTK201 was identified as the linear B-cell epitope recognized by mAb 3E9 by using a panel of GFP-tagged epitope polypeptides. Sequence alignments show that 192GWFSLHKLTK201 was highly conserved in all SVA strains. Subsequently, alanine (A)-scanning mutagenesis indicated that W193, F194, L196, and H197 were the critical residues recognized by mAb 3E9. Further investigation with indirect immunofluorescence assay indicated that the VP3 protein was present in the cytoplasm during SVA replication. In addition, the mAb 3E9 specifically immunoprecipitated the VP3 protein from SVA-infected cells. Taken together, our results indicate that mAb 3E9 could be a powerful tool to work on the function of the VP3 protein during virus infection.

Detection of Immuno Dominant Peptides against pgaB of Acinetobacter baumannii

Background: Acinetobacter baumannii is a gram negative non-motile coccobacillus, which was considered as a low priority pathogen with low virulence. Recently, it was declared as the priority pathogen under the critical category of the most dangerous pathogen by WHO. Acinetobacter Baumannii is an inhabitant of oral biofilms, and it also increases the risk of refractory periodontitis. It causes nosocomial infections with pgaB, a part of pgaABCD operon which is involved in the biofilm formation. Aim: The aim of the present study was to detect the immunodominant peptides against pgaB of Acinetobacter baumannii using bioinformatic tools and databases. Materials and Methods: The present study was carried out using immune informatics. The protein sequence of the pgaB protein from A.baumannii was subjected to assess allergenicity, secondary structure, antigenicity and stability prediction of selected T cell epitopes, physico-chemical analysis, Identification of MHC class 2 binders, Final selection of B-cell epitopes was done with IEDB B-cell epitope tool Results: Final docking of the peptides were interpreted by hydrogen bonds and interac- tion scores with TLR-2. Promising scores on antigenicity, instability were obtained. Based on the combinatorial scores, one vaccine peptide (LNLTLGLAL) was suggested to be a promising vaccine candidate against pgaB of A.baumannii. Conclusion: The findings of the present study suggest epitope LNLTLGLAL as a promising vaccine candidate against pgaB of A.baumannii. The vaccine peptides targeting the pgaB Gene in A.baumannii using an immune-informatics approach suggests promising results in the present study. However, the predicted epitope peptides need further experimentation in animal models for its application against A.baumannii.

New highly antigenic linear B cell epitope peptides from PvAMA-1 as potential vaccine candidates

Peptide-based vaccines have demonstrated to be an important way to induce long-lived immune responses and, therefore, a promising strategy in the rational of vaccine development. As to malaria, among the classic vaccine targets, the Apical membrane antigen (AMA-1) was proven to have important B cell epitopes that can induce specific immune response and, hence, became key players for a vaccine approach. The peptides selection was carried out using a bioinformatic approach based on Hidden Markov Models profiles of known antigens and propensity scale methods based on hydrophilicity and secondary structure prediction. The antigenicity of the selected B-cell peptides was assessed by multiple serological assays using sera from acute P.vivax infected subjects. The synthetic peptides were recognized by 45.5%, 48.7% and 32.2% of infected subjects for peptides I, II and III respectively. Moreover, when synthetized together (tripeptide), the reactivity increases up to 62%, which is comparable to the reactivity found against the whole protein PvAMA-1 (57%). Furthermore, IgG reactivity against the tripeptide after depletion was reduced by 42%, indicating that these epitopes may be responsible for a considerable part of the protein immunogenicity. These results represent an excellent perspective regarding future chimeric vaccine constructions that may come to contemplate several targets with the potential to generate the robust and protective immune response that a vivax malaria vaccine needs to succeed.