SDS-PAGE of A/bat/Peru/10 HA0 (lanes 1 to 4) and its mature HA (lanes 5 to 8) in trypsin susceptibility assay.

<p>A/bat/Peru/10 HA with a monobasic cleavage site was expressed in its HA0 form in a baculovirus expression system. Lanes 1 and 2 show A/bat/Peru/10 native HA0 at pH 8.0 and pH 4.9, respectively, while lanes 3 and 4 show the equivalent reducing gel of HA0 treated with trypsin at pH 8.0 and pH 4.9, respectively. Similarly, lanes 5 and 6 show A/bat/Peru/10 mature HA at pH 8.0 and pH 4.9, respectively, while lanes 7 and 8 show the equivalent reducing gel of mature HA treated with trypsin at pH 8.0 and pH 4.9, respectively.</p

Crystal structures of A/bat/Peru/10 HA.

<p>(A) Overall structure of A/bat/Peru/10 HA. The H18 HA trimer consists of three identical monomers with one RBS per monomer. HA1 is highlighted in green and HA2 in cyan. N-linked glycans observed in the electron density maps are shown with yellow carbons. (B) The A/bat/Peru/10 HA putative RBS (in crystal 1, <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003657#ppat.1003657.s014" target="_blank">Table S6</a>) in ribbon representation with the side chains of key binding residues shown. The three highly conserved residues (W153, H183, and Y195) in HAs are colored with green carbon atoms, whereas nine residues that are conserved in A/bat/Peru/10 H18 and two H17 HAs from bat influenza viruses A/little yellow-shouldered bat/Guatemala/164/2009 (H17N10) (GU09-164) and A/little yellow-shouldered bat/Guatemala/060/2010 (H17N10) (GU10-060) are labeled in red. E190 and G225 are also conserved, especially in avian influenza A viruses. (C) Molecular surface of the putative RBS of A/bat/Peru/10 HA compared to the RBS of 2009 H1 HA from A/California/04/2009 (H1N1) (PDB code 3UBQ). A canonical sialic acid is modeled in the HA for comparison as observed in other HA structures. The RBS of A/bat/Peru/10 HA is shallower and wider than 2009 H1 HA with no space for the glycerol moiety of sialic acid (indicated by the red arrow). For comparison, figures (B) and (C) are generated in the same orientation.</p

Important functional motifs in non-bat influenza A internal proteins are largely conserved in bat influenza proteins.

†<p>Letters written as subscripts denote amino acid substitutions in bat viruses compared to the consensus non-bat amino acid sequence.</p

Detection of influenza A virus and antibody in bats from Peru (2010).

<p>Detection of influenza A virus and antibody in bats from Peru (2010).</p

Crystal structures of A/bat/Peru/10 NAL.

<p>(A) Overall structure of A/bat/Peru/10 NAL with a conserved calcium binding site. The N11 NAL tetramer is viewed from above the viral surface, and consists of four identical monomers with C4 symmetry. One monomer is colored in six different colors to illustrate the canonical <i>β</i>-propeller shape of six four-stranded, anti-parallel <i>β</i>-sheets. The putative active site is located on the membrane-distal surface (on top of the molecule). The observed N-linked glycosylation sites are shown with attached carbohydrates. A single calcium ion is shown in red spheres. (B) The A/bat/Peru/10 NAL putative active site (crystal form 1, <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003657#ppat.1003657.s014" target="_blank">Table S6</a>) with the conserved catalytic and active site residues in other NAs shown as well as other polar and charged residues. The six residues (R118, W178, S179, R224, E276 and E425) conserved in all influenza NAs are colored with green carbon atoms in contrast to other putative active site residues in yellow carbon atoms, whereas eight residues that are conserved in two bat influenza N10 and N11 NAL proteins are labeled in red. (C) Molecular surface of the active site of A/bat/Peru/10 N11 NAL and 1918 N1 NA from A/Brevig Mission/1/18 (H1N1) (PDB code 3BEQ). A canonical sialic acid is modeled in A/bat/Peru/10 NAL as in other NA structures and appears to collide with the NA putative active site around the glycerol moiety (as indicated by the red arrow). The putative active site pocket of A/bat/Peru/10 NAL is much wider than 1918 N1 NA. For comparison, figures (B) and (C) are generated in the same orientation.</p