Current protocols in microbiology
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- [Show abstract] [Hide abstract] ABSTRACT: Kaposi's sarcoma-associated herpesvirus (KSHV) is a human oncovirus linked to the development of several malignancies in immunocompromised patients. Like other herpesviruses, KSHV has a large DNA genome encoding more than 100 distinct gene products. Despite being transcribed and processed by cellular machinery, the structure and organization of KSHV genes in the virus genome differ from what is observed in cellular genes from the human genome. A typical feature of KSHV expression is the production of polycistronic transcripts initiated from different promoters but sharing the same polyadenylation site (pA site). This represents a challenge in determination of the 3' end of individual viral transcripts. Such information is critical for generation of a virus transcriptional map for genetic studies. Here we present PA-seq, a high-throughput method for genome-wide analysis of pA sites of KSHV transcripts in B lymphocytes with latent or lytic KSHV infection. Besides identification of all viral pA sites, PA-seq also provides quantitative information about the levels of viral transcripts associated with each pA site, making it possible to determine the relative expression levels of viral genes at various stages of infection. Due to the indiscriminate nature of PA-seq, the pA sites of host transcripts are also concurrently mapped in the testing samples. Therefore, this technology can simultaneously estimate the expression changes of host genes and RNA polyadenylation upon KSHV infection. © 2016 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: The aim of this protocol is to describe the replication, purification, and titration of mimiviruses. These viruses belong to the Mimiviridae family, the first member of which was isolated in 1992 from a cooling tower water sample collected during an outbreak of pneumonia in a hospital in Bradford, England. In recent years, several new mimiviruses have been isolated from different environmental conditions. These giant viruses are easily replicated in amoeba of the Acanthamoeba genus, its natural host. Mimiviruses present peculiar features that make them unique viruses, such as the particle and genome size and the genome's complexity. The discovery of these viruses rekindled discussions about their origin and evolution, and the genetic and structural complexity opened up a new field of study. Here, we describe some methods utilized for mimiviruses replication, purification, and titration. © 2016 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Molecular events during the papillomavirus life cycle can be mapped in infected tissue biopsies using antibodies to viral and cellular gene products, or by in situ hybridization approaches that detect viral DNA or viral transcription products. For proteins, ease of immunodetection depends on antibody specificity and antigen availability. Epitopes in formalin-fixed paraffin-embedded (FFPE) samples are often masked by crosslinking and must be exposed for immunodetection. RNA in FFPE material is often degraded, and such tissue must be handled carefully to optimize detection. Viral proteins and viral genomic DNA are both well preserved in routinely processed FFPE samples, with sensitive detection methodologies allowing the simultaneous detection of multiple markers. The combined visualization of nucleic acid and (viral) protein targets, when coupled with image analysis approaches that allow correlation with standard pathology diagnosis, have allowed us to understand the molecular changes required for normal HPV life-cycle organization as well as deregulation during cancer progression. © 2016 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Kaposi's sarcoma-associated herpesvirus (KSHV), a human gamma-herpesvirus, is etiologically linked to the development of several malignancies, mainly Kaposi's sarcoma. Expressed as an early viral protein, KSHV ORF57 is essential for lytic replication and virion production. ORF57 selectively binds to a subset of viral RNA and affects nearly all aspects of viral RNA processing. To globally identify all viral and host RNA associated with KSHV ORF57 in the infected cells, we have utilized UV cross-linking and immunoprecipitation (CLIP) of KSHV ORF57 combined with high-throughput RNA sequencing (CLIP-seq) to identify ORF57-binding RNA in BCBL-1 cells at genome-wide level. This unit provides step-by-step details on this new method that is applicable for any pathogen or host RNA-binding proteins by slight modification. © 2016 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Ion-pumping rhodopsins transfer ions across the microbial cell membrane in a light-dependent fashion. As the rate of biochemical characterization of microbial rhodopsins begins to catch up to the rate of microbial rhodopsin identification in environmental and genomic sequence data sets, in vitro analysis of their light-absorbing properties and in vivo analysis of ion pumping will remain critical to characterizing these proteins. As we learn more about the variety of physiological roles performed by microbial rhodopsins in different cell types and environments, observing the localization patterns of the rhodopsins and/or quantifying the number of rhodopsin-bearing cells in natural environments will become more important. Here, we provide protocols for purification of rhodopsin-containing membranes, detection of ion pumping, and observation of functional rhodopsins in laboratory and environmental samples using total internal reflection fluorescence microscopy. © 2016 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Human papillomaviruses (HPVs) are small double-stranded DNA viruses that are associated with greater than 95% of cervical cancers and 20% of head and neck cancers. These cancers arise from persistent infections in which there is continued expression of the HPV E6 and E7 oncogenes, often as a consequence of integration of HPV DNA into the host genome. Such cancers represent "dead ends" for the virus as integration disrupts the viral genome and because the cancers are defective in normal epithelial differentiation, which is required for production of progeny papillomavirus. In order to study the full viral life cycle, from the establishment to maintenance to productive stages, our lab makes use of the organotypic epithelial tissue culture system. This system allows us to mimic the three-dimensional structure of epithelia whose differentiation is tightly linked to the completion of the HPV viral life cycle. In this chapter we describe how various aspects of the HPV life cycle are monitored in raft cultures making use of an immortalized keratinocyte cell line. © 2016 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Complex regulation of viral transcription patterns and DNA replication levels is a feature of many DNA viruses. This is especially true for those viruses which establish latent or persistent infections (e.g., herpesviruses, papillomaviruses, polyomaviruses, or adenovirus), as long-term persistence often requires adaptation of gene expression programs and/or replication levels to the cellular milieu. A key factor in the control of such processes is the establishment of a specific chromatin state on promoters or replication origins, which in turn will determine whether or not the underlying DNA is accessible for other factors that mediate downstream processes. Chromatin immunoprecipitation (ChIP) is a powerful technique to investigate viral chromatin, in particular to study binding patterns of modified histones, transcription factors or other DNA-/chromatin-binding proteins that regulate the viral lifecycle. Here, we provide protocols that are suitable for performing ChIP-PCR and ChIP-Seq studies on chromatin of large and small viral genomes.© 2016 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Nucleic acids can be obtained in numerous ways from clinical specimens; however, the quality of the nucleic acid is only as good as the sampling and isolation protocol. While nucleic acids may be extracted they may not be representative of the original source. Large areas of tissue and explanted hardware must be successfully surveyed to reflect the overall clinical picture. Once good sampling technique has been established, successful bacterial nucleic acid isolation is essential. Clinical samples may be difficult to process because of the presence of scar tissue, bone, implants, and bacterial biofilms. The following protocols provide details on sampling techniques and DNA isolation from a variety of clinical samples which can then be used in downstream molecular applications including PCR-MS-ESI-TOF technology. © 2016 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Papillomaviruses are a family of small, non-enveloped DNA tumor viruses. Knowing a complete transcription map of each papillomavirus genome can provide guidance for various papillomavirus studies. This unit provides detailed protocols to construct a transcription map of human papillomavirus type 18. The same approach can be easily adapted to other transcription map studies of any other papillomavirus genotype due to the high degree of conservation in genome structure, organization, and gene expression among papillomaviruses. The focused methods are 5'- and 3'-rapid amplification of cDNA ends (RACE), which are techniques commonly used in molecular biology to obtain full-length RNA transcript or to map a transcription start site (TSS) or an RNA polyadenylation (pA) cleavage site. Primer walking RT-PCR is a method for studying the splicing junction of RACE products. In addition, RNase protection assay and primer extension are also introduced as alternative methods in the mapping analysis. © 2016 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Genetic manipulation of obligate intracellular bacteria of the genus Rickettsia is currently undergoing a rapid period of change. The development of viable genetic tools, including replicative plasmids, transposons, homologous recombination, fluorescent protein-encoding genes, and antibiotic selectable markers has provided the impetus for future research development. This unit is designed to coalesce the basic methods pertaining to creation of genetically modified Rickettsia. The unit describes a series of methods, from inserting exogenous DNA into Rickettsia to the final isolation of genetically modified bacterial clones. Researchers working towards genetic manipulation of Rickettsia or similar obligate intracellular bacteria will find these protocols to be a valuable reference. © 2015 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: This unit first describes how to infect cells with vaccinia virus and then transfect them with a plasmid-transfer vector to generate a recombinant virus. Methods are also presented for purifying vaccinia virus and for isolating viral DNA, which can be used during transfection. Also presented are selection and screening methods used to isolate recombinant viruses and a method for the amplification of recombinant viruses. Finally, a method for live immunostaining that has been used primarily for detection of recombinant modified vaccinia virus Ankara (MVA) is presented.
- [Show abstract] [Hide abstract] ABSTRACT: Myxobacteria are a highly social group among the delta proteobacteria that display unique multicellular behaviors during their complex life cycle and provide a rare opportunity to study the boundary between single cells and multicellularity. These organisms are also unusual as their entire life cycle is surface associated and includes a number of social behaviors: social gliding and rippling motility, 'wolf-pack'-like predation, and self-organizing complex biostructures, termed fruiting bodies, which are filled with differentiated environmentally resistant spores. Here we present methods for the growth, maintenance, and storage of Myxococcus xanthus, the most commonly studied of the myxobacteria. We also include methods to examine various developmental and social behaviors (fruiting body and spore formation, predation, and rippling motility). As the myxobacteria, similar to the streptomycetes, are excellent sources of many characterized and uncharacterized antibiotics and other natural products, we have provided a protocol for obtaining natural isolates from a variety of environmental sources. © 2015 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: This unit is an overview of biosafety compliance and oversight in the United States. Specific attention is given to the oversight of the Institutional Biosafety Committee (IBC) and how the purview of the IBC may overlap with other local committees, such as the Institutional Animal Care and Use Committee (IACUC) for animal research and the Institutional Review Board (IRB) for research on human subjects. Requirements for the Federal Select Agent Program and Dual Use Research of Concern (DURC) are also briefly reviewed for those working with materials and experiments covered under these regulations. This unit serves as a guide for new and established investigators who are navigating the regulatory world and how regulatory oversight applies to their research. © 2015 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Human papillomaviruses (HPV) infect skin or mucosal epidermis. The simplistic capsid consists of a major capsid protein L1, a minor capsid protein L2, and a double-stranded circular DNA of about 8kB in size. The development of HPV-based vectors [i.e., pseudovirions (PsV)] as tools to study the initial infection has facilitated our understanding of HPV entry. The covalent coupling of fluorescent molecules to these PsV allows following the viruses en route to the nucleus, i.e., the site of replication. In the first section, we describe a facile method to covalently label HPV PsV that retain their infectivity. In this method, fluorophores coupled to a reactive succinimidyl ester are covalently attached to amine residues in the virion in a one-step chemical reaction. In the second section of this unit, several assays are outlined that use the fluorescently labeled virions for entry studies in live and fixed cells. © 2015 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: The vast majority of surgical biopsy and post-mortem tissue samples are formalin-fixed and paraffin-embedded (FFPE), but this process leads to RNA degradation that limits gene expression analysis. As an example, the viral RNA genome of the 1918 pandemic influenza A virus was previously determined in a 9-year effort by overlapping RT-PCR from post-mortem samples. Using the protocols described here, the full genome of the 1918 virus was determined at high coverage in one high-throughput sequencing run of a cDNA library derived from total RNA of a 1918 FFPE sample after duplex-specific nuclease treatments. This basic methodological approach should assist in the analysis of FFPE tissue samples isolated over the past century from a variety of infectious diseases. © 2015 by John Wiley & Sons, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging highly pathogenic respiratory virus. Although MERS-CoV only emerged in 2012, we and others have developed assays to grow and quantify infectious MERS-CoV and RNA products of replication in vitro. MERS-CoV is able to infect a range of cell types, but replicates to high titers in Vero E6 cells. Protocols for the propagation and quantification of MERS-CoV are presented. © 2015 by John Wiley & Sons, Inc.
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