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.

Q: doi: bioRxiv preprint 65 required for the antiviral activity of both IFITM3 and IFITM1 [9]. The subcellular localization of 66 IFITMs is a key determinant of their antiviral profile. When expressed singly, IFITM3 and IFITM2 67 preferentially localize to early and late endosomes and lysosomes, and restrict viruses that enter via 68 these endo-lysosomal compartments. In contrast, IFITM1 primarily localizes at the cell surface and 69 can restrict viruses that enter through the plasma membrane [11-14]. Indeed, mutants of IFITM3 70 that lack an N-terminal endocytic sorting motif 20 YEML 23 localize to the plasma membrane and lose 71 their ability to inhibit influenza A virus (IAV), alphavirus and coronavirus infection by endosomal 72 routes [14-18]. 73 74 Studies focusing on IFITM3 restriction of IAV and Semliki Forest Virus (SFV) indicate that virus 75 internalization is unaffected by IFITM3 expression and, for SFV at least, the viral envelope 76 . CC-BY-NC-ND 4.0 International license author/funder. It is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/737841 doi: bioRxiv preprint 109 knockout mice show enhanced morbidity after infection with IAV, alphaviruses and flaviviruses [33-110 .

A: Comparative analysis reveals adaptive evolution of bat IFITMs and a novel 1 antiviral determinant
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Q: Chemical denaturant sensitivity of the dimeric main protease from severe acute respiratory syndrome (SARS) coronavirus to guanidinium chloride was examined in terms of fluorescence spectroscopy, circular dichroism, analytical ultracentrifuge, and enzyme activity change. The dimeric enzyme dissociated at guanidinium chloride concentration of ,0.4 M, at which the enzymatic activity loss showed close correlation with the subunit dissociation. Further increase in guanidinium chloride induced a reversible biphasic unfolding of the enzyme. The unfolding of the C-terminal domain-truncated enzyme, on the other hand, followed a monophasic unfolding curve. Different mutants of the full-length protease (W31 and W207/W218), with tryptophanyl residue(s) mutated to phenylalanine at the C-terminal or N-terminal domain, respectively, were constructed. Unfolding curves of these mutants were monophasic but corresponded to the first and second phases of the protease, respectively. The unfolding intermediate of the protease thus represented a folded C-terminal domain but an unfolded N-terminal domain, which is enzymatically inactive due to loss of regulatory properties. The various enzyme forms were characterized in terms of hydrophobicity and size-and-shape distributions. We provide direct evidence for the functional role of C-terminal domain in stabilization of the catalytic N-terminal domain of SARS coronavirus main protease.

A: Reversible Unfolding of the Severe Acute Respiratory Syndrome Coronavirus Main Protease in Guanidinium Chloride
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Q: Human metapneumovirus (hMPV), a newly discovered virus of the family Paramyxoviridae, has been associated with upper and lower respiratory tract infections in different age groups in many countries. The putative attachment (G) glycoprotein of this virus was previously reported to have shown more extensive nucleotide and deduced amino acid sequence polymorphism than any other genomic regions of this virus, leading to four sub-lineages. Using a maximum likelihood-based codon substitution model of sequence evolution, here we report that sequences of extracellular domain of 8 amino acid sites in lineage 1a, and 3 amino acid sites each in lineage 1b, 2a, and 2b have a higher rate of nonsynonymous substitutions (d N ) than the synonymous substitutions (d S ) with a posterior probability above 0.95, thus suggesting the evidence of adaptive evolution driven by Darwinian selection. Although it is unclear whether these amino acid adaptations are driven by differential immune pressure or some other factors, identification of these positively selected amino acid sites would help in better screening using epitope mapping technology to identify and localize the sites that can be recognized by the immune system. We also observed surprisingly higher nucleotide substitution rates per site, per year for each lineage of hMPV than the rates that were previously reported for the human respiratory syncytial virus, suggesting rapid evolutionary dynamics of hMPV.

A:
Positive natural selection in the evolution of human metapneumovirus attachment glycoprotein
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