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.

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

Influenza infection is a major cause of morbidity and mortality worldwide, especially during pandemics outbreaks. Emerging data indicate that phase II antioxidant enzyme pathways could play a role in virusassociated inflammation and immune clearance. While Nrf2-dependent gene expression is known to modify inflammation, a mechanistic role in viral susceptibility and clearance has yet to be elucidated. Therefore, we utilized differentiated human nasal epithelial cells (NEC) and an enzymatic virus-like particle entry assay, to examine the role Nrf2-dependent gene expression has on viral entry and replication. Herein, lentiviral vectors that express Nrf2-specific short hairpin (sh)-RNA effectively decreased both Nrf2 mRNA and Nrf2 protein expression in transduced human NEC from healthy volunteers. Nrf2 knockdown correlated with a significant increase in influenza virus entry and replication. Conversely, supplementation with the potent Nrf2 activators sulforaphane (SFN) and epigallocatechin gallate (EGCG) significantly decreased viral entry and replication. The suppressive effects of EGCG on viral replication were abolished in cells with knocked-down Nrf2 expression, suggesting a causal relationship between the EGCG-induced activation of Nrf2 and the ability to protect against viral infection. Interestingly, the induction of Nrf2 via nutritional supplements SFN and EGCG increased antiviral mediators/responses: RIG-I, IFN-β, and MxA at baseline in the absence of infection. Our data indicate that there is an inverse relationship between the levels of Nrf2 expression and the viral entry/ replication. We also demonstrate that supplementation with Nrf2-activating antioxidants inhibits viral replication in human NEC, which may prove to be an attractive therapeutic intervention. Taken together, these data indicate potential mechanisms by which Nrf2-dependent gene expression regulates susceptibility to influenza in human epithelial cells.
Nrf2 expression modifies influenza A entry and replication in nasal epithelial cells ☆

Objective: In order to investigate the clinical and epidemiological rules of severe acute respiratory syndrome (sArs), rates and levels sArs coronavirus (sArs-coV) IgG antibodies of the patients and community populations from several areas were detected. Methods: Indirect immunofluorescent assay (IFA) and double-antigen sandwich enzyme-linked immunosorbent assay (ELIsA) were used to detect the sArs coronavirus-specific IgG antibodies in sera of 1700, including 1453 general populations from Hongkong, Marco, Guangzhou and Peking and 257 SARS patients from Guangzhou and Peking. The dynamics of the serum antibodies of SARS patients were observed from 3 to 360 days after onset of symptoms. Results: 90% of 257 patient serum specimens after 20 days of disease onset showed positive SARS-CoV IgG either using ELISA or IFA . 257 SARS patients, antibodies titers increased steadily in early 4 to 6 months after onset of SARS. The titers of most cases came to the peak in the 6th month. Then antibodies titers declined rapidly in some cases. However, all specimens still were positive for SARS-CoV IgG in the 48th month. Conclusions: this study suggest that few inapparent infectious patients exist during sArs epidemic. serum IgG antibodies has diagnostic value for SARS in the late course of disease and the antibodies present more than 48 months. (Int J Biomed Sci 2005; 1: 72-75) 

Seroepidemiological Study on SARS-CoV IgG Antibodies of Different Populations from Several Areas