Molecular Signatures of Hemagglutinin Stem-Directed Heterosubtypic Human Neutralizing Antibodies against Influenza A Viruses

Recent studies have shown high usage of the IGHV1-69 germline immunoglobulin gene for influenza hemagglutinin stem-directed broadly-neutralizing antibodies (HV1-69-sBnAbs). Here we show that a major structural solution for these HV1-69-sBnAbs is achieved through a critical triad comprising two CDR-H2 loop anchor residues (a hydrophobic residue at position 53 (Ile or Met) and Phe54), and CDR-H3-Tyr at positions 98±1; together with distinctive V-segment CDR amino acid substitutions that occur in positions sparse in AID/polymerase-η recognition motifs. A semi-synthetic IGHV1-69 phage-display library screen designed to investigate AID/polη restrictions resulted in the isolation of HV1-69-sBnAbs that featured a distinctive Ile52Ser mutation in the CDR-H2 loop, a universal CDR-H3 Tyr at position 98 or 99, and required as little as two additional substitutions for heterosubtypic neutralizing activity. The functional importance of the Ile52Ser mutation was confirmed by mutagenesis and by BCR studies. Structural modeling suggests that substitution of a small amino acid at position 52 (or 52a) facilitates the insertion of CDR-H2 Phe54 and CDR-H3-Tyr into adjacent pockets on the stem. These results support the concept that activation and expansion of a defined subset of IGHV1-69-encoded B cells to produce potent HV1-69-sBnAbs does not necessarily require a heavily diversified V-segment acquired through recycling/reentry into the germinal center; rather, the incorporation of distinctive amino acid substitutions by Phase 2 long-patch error-prone repair of AID-induced mutations or by random non-AID SHM events may be sufficient. We propose that these routes of B cell maturation should be further investigated and exploited as a pathway for HV1-69-sBnAb elicitation by vaccination

A multimodal cell census and atlas of the mammalian primary motor cortex

ABSTRACT We report the generation of a multimodal cell census and atlas of the mammalian primary motor cortex (MOp or M1) as the initial product of the BRAIN Initiative Cell Census Network (BICCN). This was achieved by coordinated large-scale analyses of single-cell transcriptomes, chromatin accessibility, DNA methylomes, spatially resolved single-cell transcriptomes, morphological and electrophysiological properties, and cellular resolution input-output mapping, integrated through cross-modal computational analysis. Together, our results advance the collective knowledge and understanding of brain cell type organization: First, our study reveals a unified molecular genetic landscape of cortical cell types that congruently integrates their transcriptome, open chromatin and DNA methylation maps. Second, cross-species analysis achieves a unified taxonomy of transcriptomic types and their hierarchical organization that are conserved from mouse to marmoset and human. Third, cross-modal analysis provides compelling evidence for the epigenomic, transcriptomic, and gene regulatory basis of neuronal phenotypes such as their physiological and anatomical properties, demonstrating the biological validity and genomic underpinning of neuron types and subtypes. Fourth, in situ single-cell transcriptomics provides a spatially-resolved cell type atlas of the motor cortex. Fifth, integrated transcriptomic, epigenomic and anatomical analyses reveal the correspondence between neural circuits and transcriptomic cell types. We further present an extensive genetic toolset for targeting and fate mapping glutamatergic projection neuron types toward linking their developmental trajectory to their circuit function. Together, our results establish a unified and mechanistic framework of neuronal cell type organization that integrates multi-layered molecular genetic and spatial information with multi-faceted phenotypic properties

Prevalence of Inflammatory Bowel Disease Among Patients with Autism Spectrum Disorders

Background:The objective of this study was to measure the prevalence of inflammatory bowel disease (IBD) among patients with autism spectrum disorders (ASD), which has not been well described previously.Methods:The rates of IBD among patients with and without ASD were measured in 4 study populations with distinct modes of ascertainment: a health care benefits company, 2 pediatric tertiary care centers, and a national ASD repository. The rates of IBD (established through International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes) were compared with respective controls and combined using a Stouffer meta-analysis. Clinical charts were also reviewed for IBD among patients with ICD-9-CM codes for both IBD and ASD at one of the pediatric tertiary care centers. This expert-verified rate was compared with the rate in the repository study population (where IBD diagnoses were established by expert review) and in nationally reported rates for pediatric IBD.Results:In all of case-control study populations, the rates of IBD-related ICD-9-CM codes for patients with ASD were significantly higher than that of their respective controls (Stouffer meta-analysis, P < 0.001). Expert-verified rates of IBD among patients with ASD were 7 of 2728 patients in one study population and 16 of 7201 in a second study population. The age-adjusted prevalence of IBD among patients with ASD was higher than their respective controls and nationally reported rates of pediatric IBD.Conclusions:Across each population with different kinds of ascertainment, there was a consistent and statistically significant increased prevalance of IBD in patients with ASD than their respective controls and nationally reported rates for pediatric IBD

Characterization of HV1-69-sBnAbs VH domain.

<p><b>A</b>) Alignment of 38 published HV1-69-sBnAbs is shown with highlights referring to hydrophobic residues at position 53 (light plum), the conserved Phe54 (dark plum), the occurrence of CDR-H3-Tyr (pink) residues. Other highlights refer to panel <b>B</b>), which describes the result of a Fisher's exact test with Bonferroni adjustment that compared V-segment amino acid substitutions diversity and frequency of the 37 51p1 allele related HV1-69-sBnAbs with that of a reference <i>IGHV1-69</i> 51p1 allele related Ab dataset. 13 amino acid substitutions were determined to uniquely associate with the HV1-69-sBnAb dataset (P<0.05).</p

Validating the structural role of Ser52 in HV1-69-sBnAbs.

<p><b>A</b>) F10 V-segment germline variants were analyzed for H5VN04 binding in the phage-Ab (5 scFv/phage) format by MSD ELISA <i>(left)</i> and for their ability to activate B-cell when expressed as B-cell receptors in the presence of H5VN04 <i>(right)</i>. <b>B</b>) HV1-69-sBnAb variants of S52I in F10 and A66, G52aP in CR6331, G17 and D8 were analyzed for H5VN04 reactivity by ELISA. <b>C</b>) Kinetic analysis by Biacore of F10 and A66 CDR-H2 variants against purified H5VN04. Residues colored in blue are non-germline amino acids. <b>D</b>) Circular dichroism measurement of F10 and the non-H5 reactive variant characterized by a germline configured CDR-H2 shows a highly similar CD profile for both constructs.</p

Studying the location of SHM hotspots and nucleotide substitutions frequencies in the <i>IGHV1-69</i> reference Ab dataset.

<p><b>A</b>) Number of V-segment substitutions observed in 38 HV1-69-sBnAbs with color notations that designate the HV1-69-sBnAbs characterized by the distinctive CDR-H2 Ser52 or Ala/Gly52a and “other” which do not contain CDR-H2 Ser52 or Ala/Gly52a. (<b>B–D</b>) <b>Upper panel</b> – the common nucleotide substitutions that generated the distinctive amino acid substitutions in the respective CDR domain. <b>Main panel</b> - The <i>IGHV1-69</i> 51p1 Ab reference dataset was studied for substitution frequency of nucleotides in the V-segment CDRs and for location of AID and polη hotspots (AID = WR<u>C</u>Y yellow solid triangle/R<u>G</u>YW dark red solid triangle, Polη W<u>A</u> brown open triangle/<u>T</u>W blue empty triangle. The horizontal line shows the mean±SD (6.44±7.23) of non-germline nucleotide substitution frequency observed for FR regions to serve as a reference.</p

Understanding the structural role of the distinctive CDR-H2 amino acid substitutions in HV1-69-sBnAbs.

<p>A) VDW contact analysis (black lines) shows that Ser52 of F10 and CR9114 (orange), and Ile52 of CR6261(gray) make only intramolecular contacts; i.e., do not form contacts with their respective H5VN04s. Antibodies are shown in color; HA is in light gray. At far right, steric consequences of the germline Ile52 and the Ile52Ser substitutions are shown when the Abs are overlaid on their framework residues (RMSD ∼0.5 Å). Comparing structures of the HV1-69-sBnAbs, centered on Ile52 of CR6261 (green), with F10 (yellow) and CR9114 (cyan), the Ile52Ser mutation in F10 and CR9114 enables the 2 strands to come closer together, as indicated by the yellow and cyan arrows. Distances in red indicate hypothetical steric clashes (<3 Å) that would be created if Ile52 were present in CR9114 and F10. B) Comparison between the unbound (PDB 4FQH, left) and H5VN04-bound structures (PDB 4FQI, right) of CR9114, colored according to the magnitude of structural change after superposition on the main-chain of the VH domain (from blue = 0 Å, through white = 1 Å, to red = 1.8 Å). CDRs and side-chains of the major contact residues are shown, as depicted in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004103#ppat-1004103-g001" target="_blank">Figure 1A</a>. Distances between the Cα and Cβ atoms of Phe54 and the Cα atom of CDR-H3 Tyr98 (shown as dashed lines) are indicated. Large rotations of the side chains of CDR-H3 Tyr98, CDR-H2 Phe54 and CDR-H2 Ile53 are also evident, as previously noted <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004103#ppat.1004103-Dreyfus1" target="_blank">[7]</a>.</p

Semi-synthetic HV1-69 phage-Ab library yields potent anti-H5VN04/H1CA0409 Abs characterized by a minimal V-segment amino acid substitutions.

<p><b>A</b>) Characterization of binding activities of anti-H5VN04 and anti-H1CA0409 phage-Abs isolated from the semi-synthetic HV1-69 phage-display library. Sequences are detailed in <b>Figure S4 in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004103#ppat.1004103.s001" target="_blank">Text S1</a></b>. <b>B</b>) Heavy chain CDR sequences of anti-H5VN04 phage Abs characterized by >95% neutralization activity against both H5VN04 and H1PR8 pseudotyped viruses. The 5 highlighted residues in the CDRs refer to panel <b>C</b>) which describes the result of a Chi square statistical analysis approach used to identify residues that were significantly enriched as compared to their frequency in the library (P<0.05). Also highlighted are Tyr99 and position73 in the <i>IGHV1-69</i> germline sequences.</p