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]: 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.
[A]: Differential stepwise evolution of SARS coronavirus functional proteins in different host species


[Q]: Infectious bronchitis virus (IBV), the first coronavirus described, was initially associated with severe respiratory disease. However, outbreaks have more recently also been associated with nephropathogenesis. Topographically interrelated antigenic determinants of the nephropathogenic Gray strain of IBV were characterized using eleven monoclonal antibodies (MAbs). Four MAbs (IgG 2a~c) defined epitopes that were both conformation-independent and group specific, reacting with Gray, Arkansas (Ark), and Massachusetts41 (Mass41) strains. Seven MAbs (IgG 1~:) defined conformation-dependent epitopes that could differentiate the Gray from the Ark and Mass strains. The spike protein specificity of the MAbs was determined with the conformation-independent MAbs and one MAb that reacted only in "non-denaturing" western blot assays. Competitive binding studies using these MAbs suggested a high degree of functional dependency among the associated epitopes as might be expected with a protein of complex secondary and tertiary structure. At least two regions associated with complete protection of infected embryos were identified that consisted of both conformation-dependent and independent epitopes. However, a "non-neutralizing" MAb, which did not protect the embryo from gross lesions, did inhibit virus-induced lesions and replication in the kidneys. These MAbs should be valuable tools in studying IBV pathogenesis.
[A]: Epitopes on the spike protein of a nephropathogenic strain of infectious bronchitis virus


[Q]: Abstract：In 2012, an FHV-1-like virus was isolated from a tiger that presented with clinical signs of sialorrhea, sneezing and purulent rhinorrhea. Isolation was performed with the FK81 cell line, and the virus was identified by PCR, transmission electron microscopy (TEM), and the phylogenetic analysis of the partial thymidine kinase (TK) and glycoprotein B (gB) genes. A total of 253 bp of the TK gene and 566 bp of the gB gene were amplified from the trachea of the tiger by PCR/RT-PCR method. Phylogenetic analysis showed that the isolate belonged to the same cluster with other FHV-1 strains obtained from GenBank. Herpes-like viruses with an envelope and diameters of approximately 200 nm were observed in the culture supernatants of FK81 cells inoculated with samples from the tiger. The FHV-1 infection was confirmed by an animal challenge experiment in a cat model. Viruses 2014, 6 Our finding extends the host range of FHV-1 and has implications for FHV-1 infection and South China tiger conservation.
[A]:
Isolation and Identification of Feline Herpesvirus Type 1 from a South China Tiger in China