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.
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Question: Background: SARS coronavirus (SARS-CoV) was identified as the etiological agent of SARS, and extensive investigations indicated that it originated from an animal source (probably bats) and was recently introduced into the human population via wildlife animals from wet markets in southern China. Previous studies revealed that the spike (S) protein of SARS had experienced adaptive evolution, but whether other functional proteins of SARS have undergone adaptive evolution is not known. We employed several methods to investigate selective pressure among different SARS-CoV groups representing different epidemic periods and hosts. Our results suggest that most functional proteins of SARS-CoV have experienced a stepwise adaptive evolutionary pathway. Similar to previous studies, the spike protein underwent strong positive selection in the early and middle phases, and became stabilized in the late phase. In addition, the replicase experienced positive selection only in human patients, whereas assembly proteins experienced positive selection mainly in the middle and late phases. No positive selection was found in any proteins of bat SARS-like-CoV. Furthermore, specific amino acid sites that may be the targets of positive selection in each group are identified. This extensive evolutionary analysis revealed the stepwise evolution of different functional proteins of SARS-CoVs at different epidemic stages and different hosts. These results support the hypothesis that SARS-CoV originated from bats and that the spill over into civets and humans were more recent events.

Answer: Differential stepwise evolution of SARS coronavirus functional proteins in different host species

Question: Three leading infectious disease experts in China were invited to share their bedside observations in the management of COVID-19 patients. Professor Taisheng Li was sent to Wuhan to provide frontline medical care. He depicts the clinical course of SARS-CoV-2 infection. Furthermore, he observes the significant abnormality of coagulation function and proposes that the early intravenous immunoglobulin and low molecular weight heparin anticoagulation therapy are very important. Professor Hongzhou Lu, a leader in China to try various anti-viral drugs, expresses concern on the quality of the ongoing clinical trials as most trials are small in scale and repetitive in nature, and emphasizes the importance of the quick publication of clinical trial results. Regarding the traditional Chinese medicine, Professor Lu suggests to develop a creative evaluation system because of the complicated chemical compositions. Professor Wenhong Zhang is responsible for Shanghai's overall clinical management of the COVID-19 cases. He introduces the team approach to manage COVID-19 patients. For severe or critically ill patients, in addition to the respiratory supportive treatment, timely multiorgan evaluation and treatment is very crucial. The medical decisions and interventions are carefully tailored to the unique characteristics of each patient.

Answer: Clinical observation and management of COVID-19 patients

Question: The occurrence of idiopathic pulmonary lesions in laboratory rats, characterized by lymphohistiocytic interstitial pneumonia with dense perivascular lymphoid cuffs, has been reported over the past decade. Although the term rat respiratory virus (RRV) was adopted to confer a putative viral etiology to the idiopathic pulmonary lesions, the etiology of this disease remains to be elucidated. Recently, inflammatory lesions have been observed in the lungs of immunocompetent laboratory rats similar to those previously described. Based on the latest evidence indicating that Pneumocystis carinii (P. carinii), and not putative RRV, causes infectious interstitial pneumonia in laboratory rats, the present study investigated whether the pulmonary lesions observed were caused by P. carinii infection. Male Sprague-Dawley rats, free of known pathogens, were introduced into a rat colony positive for RRV-type lesions. Routine histopathological examinations were performed on the rat lung tissues following exposure. The presence of Pneumocystis organisms was confirmed using Grocott's methenamine silver (GMS) staining. At week 3 following introduction, a few small lymphoid aggregates were located adjacent to the edematous vascular sheath. By week 5, foci of dense perivascular lymphoid cuffing were observed. Multifocal lymphohistiocytic interstitial pneumonia and prominent lymphoid perivascular cuffs were observed between week 7 and 10. GMS staining confirmed the presence of Pneumocystis cysts. Thus, the results of the present study demonstrated that P. carinii caused lymphohistiocytic interstitial pneumonia in a group of laboratory rats. The observations strongly support the conclusion that P. carinii infection in immunocompetent laboratory rats causes the lung lesions that were previously attributed to RRV.

Answer:
Histopathology of Pneumocystis carinii pneumonia in immunocompetent laboratory rats