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In the present work we aimed to develop and characterize hybrid organic–inorganic materials based on poly(vinyl alcohol) (PVA) polymer chemically modified by organosilanes and crosslinked network to be tested as solid support on immunoassay application. Hybrids were synthesized by reacting PVA with 5 different alkoxysilanes modifying chemical groups: tetraethoxysilane (TEOS), 3-mercaptopropyltriethoxysilane (MPTES), 3-glycidoxypropyltrimethoxysilane (GPTMS), 3-(triethoxysilyl)propylisocyanate (TESPI), and 3-aminopropyltriethoxysilane (APTES). PVA-derived hybrids were also modified by chemically crosslinking with glutaraldehyde (GA) during the synthesis reaction. In order to investigate the structure in the nanometer-scale, PVA-derived hybrids were characterized by using small-angle X-ray scattering synchrotron radiation (SAXS). Fourier transform infrared spectroscopy (FTIR) was used to investigate PVA hybrids chemical functionalities and their interaction with bovine herpesviruses. The morphology of silane modified PVA films were also analyzed by SEM coupled to EDX. The bioactivity assays were tested through Enzyme Linked Immunosorbent Assay (ELISA) with bovine herpesvirus (BoHV). SAXS results have indicated nano-ordered disperse domains for PVA hybrids with different X-ray scattering patterns for PVA polymer and PVA-derived hybrids. FTIR spectra have clearly showed that the proposed modifications of PVA by organosilanes were obtained. The chemical crosslinking of PVA polymer chain by GA was verified by FTIR. The immunoassay results have showed that PVA hybrids with chemically functionalized structures have played an important role on regulating to some extent the interaction of herpesvirus and solid substrate at the interface. These results have given strong evidence that PVA-derived hybrid nanocomposites were successfully formed with GA crosslinked network. Also, such PVA based material could be advantageously used in immunoassays with enhanced specificity for diagnosis.

Understanding of microbial communities inhabiting cattle vaginal tract may lead to a better comprehension of bovine physiology and reproductive health being of great economic interest. Up to date, studies involving cattle microbiota are focused on the gastrointestinal tract, and little is known about the vaginal microbiota. This study aimed to investigate the vaginal microbiome in Nellore cattle, heifers and cows, pregnant and non-pregnant, using a culture independent approach. The main bacterial phyla found were Firmicutes (~40-50%), Bacteroidetes (~15-25%) and Proteobacteria (~5-25%), in addition to ~10-20% of non-classified bacteria. 45-55% of the samples were represented by only ten OTUs: Aeribacillus, Bacteroides, Clostridium, Ruminococcus, Rikenella, Alistipes, Bacillus, Eubacterium, Prevotella and non-classified bacteria. Interestingly, microbiota from all 20 animals could be grouped according to the respiratory metabolism of the main OTUs found, creating three groups of vaginal microbiota in cattle. Archaeal samples were dominated by the Methanobrevibacter genus (Euryarchaeota, ~55-70%). Ascomycota was the main fungal phylum (~80-95%) and Mycosphaerella the most abundant genus (~70-85%). Hormonal influence was not clear, but a tendency for the reduction of bacterial and increase of archaeal populations in pregnant animals was observed. Eukaryotes did not vary significantly between pregnant and non-pregnant animals, but tended to be more abundant on cows than on heifers. The present work describes a great microbial variability in the vaginal community among the evaluated animals and groups (heifers and cows, pregnant and non-pregnant), which is significantly different from the findings previously reported using culture dependent methods, pointing out the need for further studies on this issue. The microbiome found also indicates that the vaginal colonization appears to be influenced by the gastrointestinal community.

Several barriers for the development of an HCV vaccine still exist, including the genetic diversity of the virus, and the shortage of assessable models for in vitro and in vivo assays. Therefore, in this study, HCV epitope mapping was performed for 59 polyprotein sequences from 7 HCV genotypes. Around 2,880 peptides were considered epitopes for CD8 + T cells. The peptide induction of cytokines from Th1 and/or Th2 axes of the cellular immune response was assessed, indicating a tendency for Th2 axis. In vitro evaluation was performed using peptide microarray and a recombinant HLA-A*02:01 molecule. A total of 615 peptides of high reactivity to HLA-A*02:01 were identified, with predominance of leucine and tryptophan residues, highlighting their importance for TCR-epitope binding and CD8 + T activation. Finally, HCV-derived peptide patterns restricted to HLA-A2*02:01 observed in this study provide important information for the development of a multi-epitope-based pan-genotypic vaccine against the virus.

During epidemics, data from different sources can provide information on varying aspects of the epidemic process. Serology-based epidemiologic surveys could be used to compose a consistent epidemic scenario. We assessed the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG in serum samples collected from 7,837 blood donors in 7 cities of Brazil during March-December 2020. Based on our results, we propose a modification in a compartmental model that uses reported number of SARS-CoV-2 cases and serology results from blood donors as inputs and delivers estimates of hidden variables, such as daily values of SARS-CoV-2 transmission rates and cumulative incidence rate of reported and unreported SARS-CoV-2 cases. We concluded that the information about cumulative incidence of a disease in a city's population can be obtained by testing serum samples collected from blood donors. Our proposed method also can be extended to surveillance of other infectious diseases.

In this present work, coronavirus subfamilies and SARS-CoV-2 Variants of Concern (VOCs) were investigated for the presence of MHC-I immunodominant viral peptides using in silico and tools. In our results, HLA-A*02 haplotype showed the highest number of immunodominant epitopes but with the lowest combined prediction score. Furthermore, a decrease in combined prediction score was observed for HLA-A*02-restricted epitopes when the original strain was compared to the VOCs, indicating that the mutations on the VOCs are promoting escape from HLA-A2-mediated antigen presentation, which characterizes a immune evasion process. Additionally, epitope signature analysis revealed major immunogenic peptide loss for structural (S) and non-structural (ORF8) proteins of VOCs in comparison to the Wuhan sequence. These results may indicate that the antiviral CD8 T-cell responses generated by original strains could not be sufficient for clearance of variants in either newly or reinfection with SARS-CoV-2. In contrast, N epitopes remain the most conserved and reactive peptides across SARS-CoV-2 VOCs. Overall, our data could contribute to the rational design and development of new vaccinal platforms to induce a broad cellular CD8 T cell antiviral response, aiming at controlling viral transmission of future SARS-CoV-2 variants.

IntroductionThe present work sought to identify MHC-I-restricted peptide signatures for arbovirus using in silico and in vitro peptide microarray tools.MethodsFirst, an in-silico analysis of immunogenic epitopes restricted to four of the most prevalent human MHC class-I was performed by identification of MHC affinity score. For that, more than 10,000 peptide sequences from 5 Arbovirus and 8 different viral serotypes, namely Zika (ZIKV), Dengue (DENV serotypes 1-4), Chikungunya (CHIKV), Mayaro (MAYV) and Oropouche (OROV) viruses, in addition to YFV were analyzed. Haplotype HLA-A*02.01 was the dominant human MHC for all arboviruses. Over one thousand HLA-A2 immunogenic peptides were employed to build a comprehensive identity matrix. Intending to assess HLAA*02:01 reactivity of peptides in vitro, a peptide microarray was designed and generated using a dimeric protein containing HLA-A*02:01.ResultsThe comprehensive identity matrix allowed the identification of only three overlapping peptides between two or more flavivirus sequences, suggesting poor overlapping of virus-specific immunogenic peptides amongst arborviruses. Global analysis of the fluorescence intensity for peptide-HLA-A*02:01 binding indicated a dose-dependent effect in the array. Considering all assessed arboviruses, the number of DENV-derived peptides with HLA-A*02:01 reactivity was the highest. Furthermore, a lower number of YFV-17DD overlapping peptides presented reactivity when compared to non-overlapping peptides. In addition, the assessment of HLA-A*02:01-reactive peptides across virus polyproteins highlighted non-structural proteins as “hot-spots”. Data analysis supported these findings showing the presence of major hydrophobic sites in the final segment of non-structural protein 1 throughout 2a (Ns2a) and in nonstructural proteins 2b (Ns2b), 4a (Ns4a) and 4b (Ns4b).DiscussionTo our knowledge, these results provide the most comprehensive and detailed snapshot of the immunodominant peptide signature for arbovirus with MHC-class I restriction, which may bring insight into the design of future virus-specific vaccines to arboviruses and for vaccination protocols in highly endemic areas.

The present study sought to search for the immunodominance related to the N-terminal, Central and C-terminal regions of HTLV-1 Tax using novel, cutting-edge peptide microarray analysis. In addition, in silico predictions were performed to verify the presence of nine amino acid peptides present along Tax restricted to the human leukocyte antigen (HLA)-A2.02*01 haplotype, as well as to verify the ability to induce pro-inflammatory and regulatory cytokines, such as IFN-γ and IL-4, respectively. Our results indicated abundant dose-dependent reactivity for HLA-A*02:01 in all regions (N-terminal, Central and C-terminal), but with specific hotspots. Furthermore, the results of fold-change over the Tax11–19 reactivity obtained at lower concentrations of HLA-A*02:01 reveal that peptides from the three regions contain sequences that react 100 times more than Tax11–19. On the other hand, Tax11–19 has similar or superior HLA-A*02:01 reactivity at higher concentrations of this haplotype. The in silico analysis showed a higher frequency of IFN-γ-inducing peptides in the N-terminal portion, while the C-terminal portion showed a higher frequency of IL-4 inducers. Taken together, these results shed light on the search for new Tax immunodominant epitopes, in addition to the canonic Tax11–19, for the rational design of immunomodulatory strategies for HTLV-1 chronic diseases.

Background. Dermatologic manifestations are quite common in patients with adult T cell leukemia and lymphoma and patients with myelopathy and/or tropical spastic paraparesis associated with human T cell lymphotropic virus type 1 (HTLV-1). The aim of this study was to investigate dermatological findings presented by 30 members of a Brazilian family, half of whom are infected with HTLV-1 (as confirmed by enzyme-linked immunosorbent assay and Western blot). Methods. The subjects underwent dermatologic examination and laboratory assessment, which included the search for the HTLV-1 genome in peripheral blood mononuclear cells (PBMCs) by qualitative and semiquantitative polymerase chain reaction (PCR) and in skin samples by nested qualitative PCR and immunofluorescence assay. Results. We found that cases of xerotic dermatological alterations, including 3 cases of acquired ichthyosis, were more frequent among the infected patients (7 cases vs. none among the uninfected individuals; P = .0063). Other lesions observed in this group included impetigo, scabies, epidermal nevus, herpes zoster scar, rosacea, and juvenile acne. One HTLV-1-infected individual presented with concurrently acquired ichthyosis, impetigo, scabies, dermatophytosis, and seborrheic dermatitis. The PCR performed on PBMCs and skin samples from 24 patients confirmed the serological results in all cases. Additionally, the HTLV-1 proviral load was higher in patients with >1 skin lesion. Finally, HTLV-1 could be identified in the skin by immunofluorescence assay, which, by use of PCR as the gold standard, showed a sensitivity and specificity of 61.5% and 100%, respectively. Conclusions. Altogether, these clinical and laboratory findings point to an HTLV-1 tropism toward the skin, even in HTLV-1 carriers without adult T cell leukemia/lymphoma or HTLV-1-associated myelopathy and/or tropical spastic paraparesis.

We examined the circulating BVDV species and genotypes among cattle herds from Northeast, Southeast, and Midwest regions in Brazil. A total of 77 animals tested positive through standard PCR. Phylogenetic analyses revealed the presence of BVDV-1a, highlighting the need for better surveillance strategies to prevent BVDV spread in the country.