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. 2021 Nov 23;9(12):2414. doi: 10.3390/microorganisms9122414

Figure 1.

Figure 1

Design of Bacteriophage Displaying Antigens of SARS-CoV-2 (BaDAS) recombinant phages. (A) Alignment of phage Bxb1 (Subcluster A1) and LittleGuy (Cluster A4) virion structural genes. Genomes are represented as horizontal tracks with the predicted rightwards-transcribed genes shown as colored boxes above each genome. Gene names are shown in each box and genes are colored to indicate similarity. Spectrum colored shading between genomes shows pairwise BLASTN nucleotide alignment (violet strong similarity, red weakest similarity above threshold of BLASTN E-value of 10−4); amino acid identities (%) between genes are also shown. Green and purple vertical arrows indicate the Bxb1 capsid and tail tube C-terminal extensions. (B) Alignment of Bxb1 and LittleGuy capsid and tail tube proteins; shared capsid and tail tube protein segments are colored pale green and yellow, respectively, and the Bxb1 gp14 and gp19 extensions are shown in blue. Percent amino acid identities (%) are shown. (C) Schematic representations of Bxb1 recombinant phages. phiFW1 and phiFW2 lack the gp14 C-terminal extension, and BaDAS-1–BaDAS-7 have C-terminal SARS-CoV-2 RBM additions; red (RBM30) and orange (N-term RBM30) C-terminal additions correspond to the SARS-CoV-2 Spike protein regions in panel E. (D) Schematic representation of Bxb1 gp19 recombinant phages, colored as above. (E) SARS-CoV-2 Spike protein domain organization. Domains are depicted as described previously [23], with the Receptor Binding Domain (RBM) shown in red, and its sequence [46] shown below. The RBM segments displayed in BaDAS constructs (N-term RBM30 and RBM30, denoted with orange and red arrows, respectively) span residues binding to ACE2 [23,47,48] (gray highlighted residues) or various neutralizing antibodies, denoted with colored dots (see refs [49,50,51,52,53] for details). BaDAS-1, 3, 5, and 6 contain a disulfide bond stabilizing the RBM (indicated with an arc). The constructions containing regions RBM18, RBM36, and RBM72 (18, 36 and 72-residues, respectively, shown with gray labelled lines) were unsuccessful.