Definition: 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.
Input: 2 The abbreviations used are: S, spike; SARS-CoV, severe acute respiratory syndrome coronavirus; MLV, murine leukemia virus; DC-SIGN, dendritic cell-specific intercellular adhesion molecule-3-gubbing non-integrin, ACE2, argiotensin I conserting enzyme 2. FIGURE 4. Introduction of alanine residues in the S2 region modulates elastase-induced virus entry mediated by SARS-CoV S. A and B, pseudotyped virion infections were performed as described for Fig. 2. Infection was induced by treatment with elastase (A) or trypsin (B). Results are presented as relative light units (RLU). Error bars represent the S.E. of three independent experiments. C, cleavage of SARS-CoV by elastase. HEK293T cells expressing the wild type (WT) or mutant SARS-CoV spike protein were treated with 50 g/ml elastase. Cell surface proteins were biotinylated and precipitated, and cleavage products of the SARS-CoV spike protein were analyzed in Western blot with an antibody recognizing the C9 tag at the C terminus of the protein.

Elastase-mediated Activation of the Severe Acute Respiratory Syndrome Coronavirus Spike Protein at Discrete Sites within the S2 Domain * □ S