September 22, 2019  |  

Androgen receptor variant AR-V9 is co-expressed with AR-V7 in prostate cancer metastases and predicts abiraterone resistance.

Purpose: Androgen receptor (AR) variant AR-V7 is a ligand-independent transcription factor that promotes prostate cancer resistance to AR-targeted therapies.  Accordingly, efforts are underway to develop strategies for monitoring and inhibiting AR-V7 in castration-resistant prostate cancer (CRPC).  The purpose of this study was to understand whether other AR variants may be co-expressed with AR-V7 and promote resistance to AR-targeted therapies. Experimental Design:  We utilized complementary short- and long-read sequencing of intact AR mRNA isoforms to characterize AR expression in CRPC models.  Co-expression of AR-V7 and AR-V9 mRNA in CRPC metastases and circulating tumor cells was assessed by RNA-seq and RT-PCR, respectively.  Expression of AR-V9 protein in CRPC models was evaluated with polyclonal antisera.  Multivariate analysis was performed to test whether AR variant mRNA expression in metastatic tissues was associated with a 12-week progression-free survival endpoint in a prospective clinical trial of 78 CRPC-stage patients initiating therapy with the androgen synthesis inhibitor, abiraterone acetate. Results: AR-V9 was frequently co-expressed with AR-V7.  Both AR variant species were found to share a common 3′ terminal cryptic exon, which rendered AR-V9 susceptible to experimental manipulations that were previously-thought to target AR-V7 uniquely.  AR-V9 promoted ligand-independent growth of prostate cancer cells.  High AR-V9 mRNA expression in CRPC metastases was predictive of primary resistance to abiraterone acetate (HR = 4.0, 95% CI = 1.31-12.2, P = 0.02).   Conclusions:  AR-V9 may be an important component of therapeutic resistance in CRPC. Copyright ©2017, American Association for Cancer Research.

September 22, 2019  |  

The role of MHC-E in T cell immunity is conserved among humans, rhesus macaques, and cynomolgus macaques.

MHC-E is a highly conserved nonclassical MHC class Ib molecule that predominantly binds and presents MHC class Ia leader sequence-derived peptides for NK cell regulation. However, MHC-E also binds pathogen-derived peptide Ags for presentation to CD8+ T cells. Given this role in adaptive immunity and its highly monomorphic nature in the human population, HLA-E is an attractive target for novel vaccine and immunotherapeutic modalities. Development of HLA-E-targeted therapies will require a physiologically relevant animal model that recapitulates HLA-E-restricted T cell biology. In this study, we investigated MHC-E immunobiology in two common nonhuman primate species, Indian-origin rhesus macaques (RM) and Mauritian-origin cynomolgus macaques (MCM). Compared to humans and MCM, RM expressed a greater number of MHC-E alleles at both the population and individual level. Despite this difference, human, RM, and MCM MHC-E molecules were expressed at similar levels across immune cell subsets, equivalently upregulated by viral pathogens, and bound and presented identical peptides to CD8+ T cells. Indeed, SIV-specific, Mamu-E-restricted CD8+ T cells from RM recognized antigenic peptides presented by all MHC-E molecules tested, including cross-species recognition of human and MCM SIV-infected CD4+ T cells. Thus, MHC-E is functionally conserved among humans, RM, and MCM, and both RM and MCM represent physiologically relevant animal models of HLA-E-restricted T cell immunobiology. Copyright © 2017 by The American Association of Immunologists, Inc.

September 22, 2019  |  

Rodent papillomaviruses.

Preclinical infection model systems are extremely valuable tools to aid in our understanding of Human Papillomavirus (HPV) biology, disease progression, prevention, and treatments. In this context, rodent papillomaviruses and their respective infection models are useful tools but remain underutilized resources in the field of papillomavirus biology. Two rodent papillomaviruses, MnPV1, which infects the Mastomys species of multimammate rats, and MmuPV1, which infects laboratory mice, are currently the most studied rodent PVs. Both of these viruses cause malignancy in the skin and can provide attractive infection models to study the lesser understood cutaneous papillomaviruses that have been frequently associated with HPV-related skin cancers. Of these, MmuPV1 is the first reported rodent papillomavirus that can naturally infect the laboratory strain of mice. MmuPV1 is an attractive model virus to study papillomavirus pathogenesis because of the ubiquitous availability of lab mice and the fact that this mouse species is genetically modifiable. In this review, we have summarized the knowledge we have gained about PV biology from the study of rodent papillomaviruses and point out the remaining gaps that can provide new research opportunities.

September 22, 2019  |  

No assembly required: Full-length MHC class I allele discovery by PacBio circular consensus sequencing.

Single-molecule real-time (SMRT) sequencing technology with the Pacific Biosciences (PacBio) RS II platform offers the potential to obtain full-length coding regions (~1100-bp) from MHC class I cDNAs. Despite the relatively high error rate associated with SMRT technology, high quality sequences can be obtained by circular consensus sequencing (CCS) due to the random nature of the error profile. In the present study we first validated the ability of SMRT-CCS to accurately identify class I transcripts in Mauritian-origin cynomolgus macaques (Macaca fascicularis) that have been characterized previously by cloning and Sanger-based sequencing as well as pyrosequencing approaches. We then applied this SMRT-CCS method to characterize 60 novel full-length class I transcript sequences expressed by a cohort of cynomolgus macaques from China. The SMRT-CCS method described here provides a straightforward protocol for characterization of unfragmented single-molecule cDNA transcripts that will potentially revolutionize MHC class I allele discovery in nonhuman primates and other species. Published by Elsevier Inc.

September 22, 2019  |  

Single-molecule long-read 16S sequencing to characterize the lung microbiome from mechanically ventilated patients with suspected pneumonia.

In critically ill patients, the development of pneumonia results in significant morbidity and mortality and additional health care costs. The accurate and rapid identification of the microbial pathogens in patients with pulmonary infections might lead to targeted antimicrobial therapy with potentially fewer adverse effects and lower costs. Major advances in next-generation sequencing (NGS) allow culture-independent identification of pathogens. The present study used NGS of essentially full-length PCR-amplified 16S ribosomal DNA from the bronchial aspirates of intubated patients with suspected pneumonia. The results from 61 patients demonstrated that sufficient DNA was obtained from 72% of samples, 44% of which (27 samples) yielded PCR amplimers suitable for NGS. Out of the 27 sequenced samples, only 20 had bacterial culture growth, while the microbiological and NGS identification of bacteria coincided in 17 (85%) of these samples. Despite the lack of bacterial growth in 7 samples that yielded amplimers and were sequenced, the NGS identified a number of bacterial species in these samples. Overall, a significant diversity of bacterial species was identified from the same genus as the predominant cultured pathogens. The numbers of NGS-identifiable bacterial genera were consistently higher than identified by standard microbiological methods. As technical advances reduce the processing and sequencing times, NGS-based methods will ultimately be able to provide clinicians with rapid, precise, culture-independent identification of bacterial, fungal, and viral pathogens and their antimicrobial sensitivity profiles. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

September 22, 2019  |  

Meeting report: 31st International Mammalian Genome Conference, Mammalian Genetics and Genomics: From Molecular Mechanisms to Translational Applications.

High on the Heidelberg hills, inside the Advanced Training Centre of the European Molecular Biology Laboratory (EMBL) campus with its unique double-helix staircase, scientists gathered for the EMBL conference “Mammalian Genetics and Genomics: From Molecular Mechanisms to Translational Applications,” organized in cooperation with the International Mammalian Genome Society (IMGS) and the Mouse Molecular Genetics (MMG) group. The conference attracted 205 participants from 30 countries, representing 6 of the 7 continents-all except Antarctica. It was a richly diverse group of geneticists, clinicians, and bioinformaticians, with presentations by established and junior investigators, including many trainees. From the 24th-27th of October 2017, they shared exciting advances in mammalian genetics and genomics research, from the introduction of cutting-edge technologies to descriptions of translational studies involving highly relevant models of human disease.

September 22, 2019  |  

Major histocompatibility complex haplotyping and long-amplicon allele discovery in cynomolgus macaques from Chinese breeding facilities.

Very little is currently known about the major histocompatibility complex (MHC) region of cynomolgus macaques (Macaca fascicularis; Mafa) from Chinese breeding centers. We performed comprehensive MHC class I haplotype analysis of 100 cynomolgus macaques from two different centers, with animals from different reported original geographic origins (Vietnamese, Cambodian, and Cambodian/Indonesian mixed-origin). Many of the samples were of known relation to each other (sire, dam, and progeny sets), making it possible to characterize lineage-level haplotypes in these animals. We identified 52 Mafa-A and 74 Mafa-B haplotypes in this cohort, many of which were restricted to specific sample origins. We also characterized full-length MHC class I transcripts using Pacific Biosciences (PacBio) RS II single-molecule real-time (SMRT) sequencing. This technology allows for complete read-through of unfragmented MHC class I transcripts (~1100 bp in length), so no assembly is required to unambiguously resolve novel full-length sequences. Overall, we identified 311 total full-length transcripts in a subset of 72 cynomolgus macaques from these Chinese breeding facilities; 130 of these sequences were novel and an additional 115 extended existing short database sequences to span the complete open reading frame. This significantly expands the number of Mafa-A, Mafa-B, and Mafa-I full-length alleles in the official cynomolgus macaque MHC class I database. The PacBio technique described here represents a general method for full-length allele discovery and genotyping that can be extended to other complex immune loci such as MHC class II, killer immunoglobulin-like receptors, and Fc gamma receptors.

September 22, 2019  |  

Interpreting microbial biosynthesis in the genomic age: Biological and practical considerations.

Genome mining has become an increasingly powerful, scalable, and economically accessible tool for the study of natural product biosynthesis and drug discovery. However, there remain important biological and practical problems that can complicate or obscure biosynthetic analysis in genomic and metagenomic sequencing projects. Here, we focus on limitations of available technology as well as computational and experimental strategies to overcome them. We review the unique challenges and approaches in the study of symbiotic and uncultured systems, as well as those associated with biosynthetic gene cluster (BGC) assembly and product prediction. Finally, to explore sequencing parameters that affect the recovery and contiguity of large and repetitive BGCs assembled de novo, we simulate Illumina and PacBio sequencing of the Salinispora tropica genome focusing on assembly of the salinilactam (slm) BGC.

September 22, 2019  |  

The full transcription map of mouse papillomavirus type 1 (MmuPV1) in mouse wart tissues.

Mouse papillomavirus type 1 (MmuPV1) provides, for the first time, the opportunity to study infection and pathogenesis of papillomaviruses in the context of laboratory mice. In this report, we define the transcriptome of MmuPV1 genome present in papillomas arising in experimentally infected mice using a combination of RNA-seq, PacBio Iso-seq, 5′ RACE, 3′ RACE, primer-walking RT-PCR, RNase protection, Northern blot and in situ hybridization analyses. We demonstrate that the MmuPV1 genome is transcribed unidirectionally from five major promoters (P) or transcription start sites (TSS) and polyadenylates its transcripts at two major polyadenylation (pA) sites. We designate the P7503, P360 and P859 as “early” promoters because they give rise to transcripts mostly utilizing the polyadenylation signal at nt 3844 and therefore can only encode early genes, and P7107 and P533 as “late” promoters because they give rise to transcripts utilizing polyadenylation signals at either nt 3844 or nt 7047, the latter being able to encode late, capsid proteins. MmuPV1 genome contains five splice donor sites and three acceptor sites that produce thirty-six RNA isoforms deduced to express seven predicted early gene products (E6, E7, E1, E1^M1, E1^M2, E2 and E8^E2) and three predicted late gene products (E1^E4, L2 and L1). The majority of the viral early transcripts are spliced once from nt 757 to 3139, while viral late transcripts, which are predicted to encode L1, are spliced twice, first from nt 7243 to either nt 3139 (P7107) or nt 757 to 3139 (P533) and second from nt 3431 to nt 5372. Thirteen of these viral transcripts were detectable by Northern blot analysis, with the P533-derived late E1^E4 transcripts being the most abundant. The late transcripts could be detected in highly differentiated keratinocytes of MmuPV1-infected tissues as early as ten days after MmuPV1 inoculation and correlated with detection of L1 protein and viral DNA amplification. In mature warts, detection of L1 was also found in more poorly differentiated cells, as previously reported. Subclinical infections were also observed. The comprehensive transcription map of MmuPV1 generated in this study provides further evidence that MmuPV1 is similar to high-risk cutaneous beta human papillomaviruses. The knowledge revealed will facilitate the use of MmuPV1 as an animal virus model for understanding of human papillomavirus gene expression, pathogenesis and immunology.

September 22, 2019  |  

Improved full-length killer cell immunoglobulin-like receptor transcript discovery in Mauritian cynomolgus macaques.

Killer cell immunoglobulin-like receptors (KIRs) modulate disease progression of pathogens including HIV, malaria, and hepatitis C. Cynomolgus and rhesus macaques are widely used as nonhuman primate models to study human pathogens, and so, considerable effort has been put into characterizing their KIR genetics. However, previous studies have relied on cDNA cloning and Sanger sequencing that lack the throughput of current sequencing platforms. In this study, we present a high throughput, full-length allele discovery method utilizing Pacific Biosciences circular consensus sequencing (CCS). We also describe a new approach to Macaque Exome Sequencing (MES) and the development of the Rhexome1.0, an adapted target capture reagent that includes macaque-specific capture probe sets. By using sequence reads generated by whole genome sequencing (WGS) and MES to inform primer design, we were able to increase the sensitivity of KIR allele discovery. We demonstrate this increased sensitivity by defining nine novel alleles within a cohort of Mauritian cynomolgus macaques (MCM), a geographically isolated population with restricted KIR genetics that was thought to be completely characterized. Finally, we describe an approach to genotyping KIRs directly from sequence reads generated using WGS/MES reads. The findings presented here expand our understanding of KIR genetics in MCM by associating new genes with all eight KIR haplotypes and demonstrating the existence of at least one KIR3DS gene associated with every haplotype.

September 22, 2019  |  

KIR3DL01 upregulation on gut natural killer cells in response to SIV infection of KIR- and MHC class I-defined rhesus macaques.

Natural killer cells provide an important early defense against viral pathogens and are regulated in part by interactions between highly polymorphic killer-cell immunoglobulin-like receptors (KIRs) on NK cells and their MHC class I ligands on target cells. We previously identified MHC class I ligands for two rhesus macaque KIRs: KIR3DL01 recognizes Mamu-Bw4 molecules and KIR3DL05 recognizes Mamu-A1*002. To determine how these interactions influence NK cell responses, we infected KIR3DL01+ and KIR3DL05+ macaques with and without defined ligands for these receptors with SIVmac239, and monitored NK cell responses in peripheral blood and lymphoid tissues. NK cell responses in blood were broadly stimulated, as indicated by rapid increases in the CD16+ population during acute infection and sustained increases in the CD16+ and CD16-CD56- populations during chronic infection. Markers of proliferation (Ki-67), activation (CD69 & HLA-DR) and antiviral activity (CD107a & TNFa) were also widely expressed, but began to diverge during chronic infection, as reflected by sustained CD107a and TNFa upregulation by KIR3DL01+, but not by KIR3DL05+ NK cells. Significant increases in the frequency of KIR3DL01+ (but not KIR3DL05+) NK cells were also observed in tissues, particularly in the gut-associated lymphoid tissues, where this receptor was preferentially upregulated on CD56+ and CD16-CD56- subsets. These results reveal broad NK cell activation and dynamic changes in the phenotypic properties of NK cells in response to SIV infection, including the enrichment of KIR3DL01+ NK cells in tissues that support high levels of virus replication.

September 22, 2019  |  

Novel full-length major histocompatibility complex class I allele discovery and haplotype definition in pig-tailed macaques.

Pig-tailed macaques (Macaca nemestrina, Mane) are important models for human immunodeficiency virus (HIV) studies. Their infectability with minimally modified HIV makes them a uniquely valuable animal model to mimic human infection with HIV and progression to acquired immunodeficiency syndrome (AIDS). However, variation in the pig-tailed macaque major histocompatibility complex (MHC) and the impact of individual transcripts on the pathogenesis of HIV and other infectious diseases is understudied compared to that of rhesus and cynomolgus macaques. In this study, we used Pacific Biosciences single-molecule real-time circular consensus sequencing to describe full-length MHC class I (MHC-I) transcripts for 194 pig-tailed macaques from three breeding centers. We then used the full-length sequences to infer Mane-A and Mane-B haplotypes containing groups of MHC-I transcripts that co-segregate due to physical linkage. In total, we characterized full-length open reading frames (ORFs) for 313 Mane-A, Mane-B, and Mane-I sequences that defined 86 Mane-A and 106 Mane-B MHC-I haplotypes. Pacific Biosciences technology allows us to resolve these Mane-A and Mane-B haplotypes to the level of synonymous allelic variants. The newly defined haplotypes and transcript sequences containing full-length ORFs provide an important resource for infectious disease researchers as certain MHC haplotypes have been shown to provide exceptional control of simian immunodeficiency virus (SIV) replication and prevention of AIDS-like disease in nonhuman primates. The increased allelic resolution provided by Pacific Biosciences sequencing also benefits transplant research by allowing researchers to more specifically match haplotypes between donors and recipients to the level of nonsynonymous allelic variation, thus reducing the risk of graft-versus-host disease.

September 22, 2019  |  

Comparative genomics of Escherichia coli sequence type 219 clones from the same patient: Evolution of the IncI1 blaCMY-carrying plasmid in vivo.

This study investigates the evolution of an Escherichia coli sequence type 219 clone in a patient with recurrent urinary tract infection, comparing isolate EC974 obtained prior to antibiotic treatment and isolate EC1515 recovered after exposure to several ß-lactam antibiotics (ceftriaxone, cefixime, and imipenem). EC974 had a smooth colony morphology, while EC1515 had a rough colony morphology on sheep blood agar. RAPD-PCR analysis suggested that both isolates belonged to the same clone. Antimicrobial susceptibility tests showed that EC1515 was more resistant to piperacillin/tazobactam, cefepime, cefpirome, and ertapenem than EC974. Comparative genomic analysis was used to investigate the genetic changes of EC974 and EC1515 within the host, and showed three plasmids with replicons IncI1, P0111, and IncFII in both isolates. P0111-type plasmids pEC974-2 and pEC1515-2, contained the antibiotic resistance genes aadA2, tetA, and drfA12. IncFII-type plasmids pEC974-3 and pEC1515-3 contained the antibiotic resistance genes blaTEM-1, aadA1, aadA22, sul3, and inuF. Interestingly, blaCMY-111 and blaCMY-4 were found in very similar IncI1 plasmids that also contained aadA22 and aac(3)-IId, from isolates EC974 (pEC974-1) and EC1515 (pEC1515-1), respectively. The results showed in vivo amino acid substitutions converting blaCMY-111 to blaCMY-4 (R221W and A238V substitutions). Conjugation experiments showed a high frequency of IncI1 and IncFII plasmid co-transference. Transconjugants and DH5a cells harboring blaCMY-4 or blaCMY-111 showed higher levels of resistance to ampicillin, amoxicillin, cefazolin, cefuroxime, cefotaxime, cefixime, and ceftazidime, but not piperacillin/tazobactam, cefpime, or ertapenem. All known genes (outer membrane proteins and extended-spectrum AmpC ß-lactamases) involved in ETP resistance in E. coli were identical between EC974 and EC1515. This is the first study to identify the evolution of an IncI1 plasmid within the host, and to characterize blaCMY-111 in E. coli.

September 22, 2019  |  

The integrative conjugative element clc (ICEclc) of Pseudomonas aeruginosa JB2.

Integrative conjugative elements (ICE) are a diverse group of chromosomally integrated, self-transmissible mobile genetic elements (MGE) that are active in shaping the functions of bacteria and bacterial communities. Each type of ICE carries a characteristic set of core genes encoding functions essential for maintenance and self-transmission, and cargo genes that endow on hosts phenotypes beneficial for niche adaptation. An important area to which ICE can contribute beneficial functions is the biodegradation of xenobiotic compounds. In the biodegradation realm, the best-characterized ICE is ICEclc, which carries cargo genes encoding for ortho-cleavage of chlorocatechols (clc genes) and aminophenol metabolism (amn genes). The element was originally identified in the 3-chlorobenzoate-degrader Pseudomonas knackmussii B13, and the closest relative is a nearly identical element in Burkholderia xenovorans LB400 (designated ICEclc-B13 and ICEclc-LB400, respectively). In the present report, genome sequencing of the o-chlorobenzoate degrader Pseudomonas aeruginosa JB2 was used to identify a new member of the ICEclc family, ICEclc-JB2. The cargo of ICEclc-JB2 differs from that of ICEclc-B13 and ICEclc-LB400 in consisting of a unique combination of genes that encode for the utilization of o-halobenzoates and o-hydroxybenzoate as growth substrates (ohb genes and hyb genes, respectively) and which are duplicated in a tandem repeat. Also, ICEclc-JB2 lacks an operon of regulatory genes (tciR-marR-mfsR) that is present in the other two ICEclc, and which controls excision from the host. Thus, the mechanisms regulating intracellular behavior of ICEclc-JB2 may differ from that of its close relatives. The entire tandem repeat in ICEclc-JB2 can excise independently from the element in a process apparently involving transposases/insertion sequence associated with the repeats. Excision of the repeats removes important niche adaptation genes from ICEclc-JB2, rendering it less beneficial to the host. However, the reduced version of ICEclc-JB2 could now acquire new genes that might be beneficial to a future host and, consequently, to the survival of ICEclc-JB2. Collectively, the present identification and characterization of ICEclc-JB2 provides insights into roles of MGE in bacterial niche adaptation and the evolution of catabolic pathways for biodegradation of xenobiotic compounds.

July 19, 2019  |  

The deep origin and recent loss of venom toxin genes in rattlesnakes.

The genetic origin of novel traits is a central but challenging puzzle in evolutionary biology. Among snakes, phospholipase A2 (PLA2)-related toxins have evolved in different lineages to function as potent neurotoxins, myotoxins, or hemotoxins. Here, we traced the genomic origin and evolution of PLA2 toxins by examining PLA2 gene number, organization, and expression in both neurotoxic and non-neurotoxic rattlesnakes. We found that even though most North American rattlesnakes do not produce neurotoxins, the genes of a specialized heterodimeric neurotoxin predate the origin of rattlesnakes and were present in their last common ancestor (~22 mya). The neurotoxin genes were then deleted independently in the lineages leading to the Western Diamondback (Crotalus atrox) and Eastern Diamondback (C. adamanteus) rattlesnakes (~6 mya), while a PLA2 myotoxin gene retained in C. atrox was deleted from the neurotoxic Mojave rattlesnake (C. scutulatus; ~4 mya). The rapid evolution of PLA2 gene number appears to be due to transposon invasion that provided a template for non-allelic homologous recombination. Copyright © 2016 Elsevier Ltd. All rights reserved.

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