In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.

Arenaviruses are a family of enveloped RNA viruses that cause severe human disease. The first step in the arenavirus life cycle is attachment of viral particles to host cells. While virus-cell attachment can be measured through the use of virions labeled with biotin, radioactive isotopes, or fluorescent dyes, these approaches typically require high multiplicities of infection (MOI) to enable detection of bound virus. We describe a quantitative (q)RT-PCR-based assay that measures Junin virus strain Candid 1 attachment via quantitation of virion-packaged viral genomic RNA. This assay has several advantages including its extreme sensitivity and ability to measure attachment over a large dynamic range of MOIs without the need to purify or label input virus. Importantly, this approach can be easily tailored for use with other viruses through the use of virus-specific qRT-PCR reagents. Further, this assay can be modified to permit measurement of particle endocytosis and genome uncoating. In conclusion, we describe a simple, yet robust assay for highly sensitive measurement of arenavirus-cell attachment. The video component of this article can be found at http://www.jove.com/video/53682/ 15, 23 . The qRT-PCR-based assay described here can detect attachment events using as few as 20 plaque forming units (PFUs) of virus, which translates into an MOI of 0.0004 for a 48-well plate. Therefore, the strong sensitivity of the assay overcomes the requirement for high MOI as well as any virus labeling or concentration steps. Further, the assay can be i) adapted to measure virion endocytosis Journal of Visualized Experiments
Highly Sensitive Assay for Measurement of Arenavirus-cell Attachment

ATP-dependent chromatin remodelling proteins represent a diverse family of proteins that share ATPase domains that are adapted to regulate protein-DNA interactions. Here we present structures of the yeast Chd1 protein engaged with nucleosomes in the presence of the transition state mimic ADP-beryllium fluoride. The path of DNA strands through the ATPase domains indicates the presence of contacts conserved with single strand translocases and additional contacts with both strands that are unique to Snf2 related proteins. The structure provides connectivity between rearrangement of ATPase lobes to a closed, nucleotide bound state and the sensing of linker DNA. Two turns of linker DNA are prised off the surface of the histone octamer as a result of Chd1 binding, and both the histone H3 tail and ubiquitin conjugated to lysine 120 are re-orientated towards the unravelled DNA. This indicates how changes to nucleosome structure can alter the way in which histone epitopes are presented.
Structure of the chromatin remodelling enzyme Chd1 bound to a ubiquitinylated nucleosome

Mouse hepatitis virus, a coronavirus, was rescued from latently infected mouse neuroblastoma cells by polyethylene glyeol-induced fusion to permissive cells. The isolated viruses grew to equal or higher titers than parental JHM virus at 39" but were restricted in replication at 32" and hence were cold-sensitive mutants. Neither isolate synthesized RNA at the nonpermissive temperature (32"), and temperature shift experiments indicated that the restrictive cold-sensitive step in replication occurred during an early viral function. The isolates were unable to complement each other at 32". Although coinfection between each mutant and parental JHM virus often resulted in decreased yields of both infecting viruses, interference could not be convincingly demonstrated. Both mutants were more thermostable than parental JHM virus and could be distinguished from each other and from parental JHM virus by their thermal inactivation kinetics. The isolates were obtained from single cell clones and therefore presumed to be homogeneous; however, thermal inactivation of one (S-3JHM) indicated the possible existence of a second population. Subclones of virus prepared from each isolate were also found to be thermally stable and to retain the cold sensitive defect. No indication of a second ~pulation of S-3JHM virus was detected.

Characterization of the Cold-Sensitive Murine Hepatitis Virus Mutants Rescued from Latently Infected Cells by Cell Fusion