There is a need for an improved vaccine for tuberculosis. ESAT-6 is a cardinal vaccine antigen with unique properties and is included in several vaccine candidates in development. ESAT-6 is also the core antigen in the IFN-γ release assays (IGRA) used to diagnose latent infection, rendering IGRA tests unspecific after vaccination. This challenge has prompted the development of a companion diagnostic for ESAT-6 based vaccines, an ESAT-6 free IGRA. We screened a panel of seven potential new diagnostic antigens not recognized in BCG vaccinated individuals. Three highly recognized antigens EspC, EspF and Rv2348c were identified and combined with CFP10 in an ESAT-6 free antigen cocktail. The cocktail was prepared in a field-friendly format, lyophilized with heparin in ready-to-use vacutainer tubes. The diagnostic performance of the ESAT-6 free IGRA was determined in a cross-validation study. Compared IGRA, the ESAT-6 free IGRA induced a comparable magnitude of IFN-γ release, and the diagnostic performance was on par with Quantiferon (sensitivity 84% vs 79%; specificity 99% vs 97%). The comparable performance of the ESAT-6 free IGRA to IGRA suggests potential as companion diagnostic for ESAT-6 containing vaccines and as adjunct test for latent infection.

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Background Surveillance for circulating emerging diseases of economic importance has a major role in the rapid response to major pathogen outbreaks. Foot-and-mouth disease virus (FMDV) is one of the significant endemic viruses in Egypt. FMDV is periodically investigated for monitoring evolution and emergence of new variants. The genetic characterization of foot-and-mouth disease (FMD) virus serotype A responsible for recent outbreaks of FMD in Egypt was determined. Methods Samples were collected from different locations and virus isolation was performed using BHK-21 cells. Viral RNA was extracted and samples were screened for FMDV using real-time RT-PCR. DNA sequence analysis was performed and computational and bioinformatics analyses were used to determine the substitution rates and phylogenetic relationship. Results Sequence and phylogenetic analyses of full-length 1D region of FMDV samples collected from different governorates in 2020 showed close similarity to Egyptian FMDV strains from serotype A-African topotype-G-IV with genetic variation of 6.5%. Recently isolated FMDV strains showed high genetic variations from locally used vaccine strains in the major antigenic sites of VP1 region. Conclusions Although, efforts made by the veterinary authorities to implement an effective mass vaccination plan, the recently detected FMDV strains in this study could not be subtyped using the FMDV primers routinely used for molecular serotyping. These dissimilarities raise the alarm for reconsideration of the FMDV isolates used in vaccine manufacture. Clearly close monitoring of FMD in Egypt is urgently required to define the risks of future outbreaks and to ensure appropriate control measures against FMD major outbreaks.

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Foot and Mouth Disease Virus causes continuously annoying outbreaks and massive animal illnesses. Usually, the potential influence of the disease was due to the emergence of conquered emergent new strains or re-emergence of local strains with major antigenic variations due to the mutation in the genetic strip. Therefore, the proposed work is based on the genetic characterization of the virus by VP1 codon sequencing in the tested samples. Besides, the viral physiological testing using BHK-21 cell lines and the ELISA test for FMDV antigen serotyping. Positive serotype A samples were furtherly analyzed for nucleotide sequencing. The resulting sequences showed that they belonged to the FMD serotype A African topotypes originating from the ancestor prototype SUD/77 with a similarity of 98.48 ± 1.2% with each other. The divergence was 9.3% from the other local isolates from 2020. Additionally, they are closely related to the Egyptian-Damietta type-2016 and the Sudanese-2018 by 96.84 ± 1.01% and 95.84 ± 0.79%, respectively. Moreover, the divergence with the vaccinal strains ranged from 10 to 17%. Ultimately, the analysis of the amino acid showed that the isolates have variation in the most prominent antigenic regionsof of, allocated at residues 35–75, and at the immunogenic determinants of the G-H loop of VP1 (residues 100–146, residues 161–175). Therefore, the current isolates should be included in the vaccine to provide broader immunogenic coverages against serotype A-African topotypes.