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: 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
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Q: To elucidate the impact of a hepatitis B (HB) vaccination program on the prevalence of HB surface antigen (HBsAg) and HB envelope antigen (HBeAg) as well as the success rate of HBeAg clearance among parturients, we collected data on parturients who gave birth between 2000 and 2010, and recorded the HB status postpartum of those with positive HBeAg before birth. A total of 8696 parturients were enrolled, of whom 113 with prenatal positive HBeAg were invited back. The prevalence of HBsAg decreased over the study period, particularly in the vaccinated cohort, while there was no change in the prevalence of HBeAg. Foreign parturients had a higher HBeAg-positive rate and delayed HBeAg clearance, and those with a higher body mass index (>24 kg/m 2 ) had earlier HBeAg clearance (51.9% vs. 23.9%, p = 0.005). Only 30% of the subjects who were positive for HBeAg before birth became negative 5 years after delivery. In conclusion, the downward trend in HB infection with more significance among vaccinated parturients reflects effective prevention and the impact of universal HB immunization. Nonetheless, aggressive follow-up is necessary for parturients who are persistently positive for HBeAg postpartum, as well as developing different public health policies for foreign parturients from endemic areas. Published: xx xx xxxx OPEN www.nature.com/scientificreports/ 2 Scientific RepoRts | 7: 1212 |

A: Changes in the Prevalence of HBsAg and HBeAg: a Study of 8696 Parturients in a Well Vaccinated Area OPEN
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Q: Porcine reproductive and respiratory syndrome virus (PRRSV) RNA endoribonuclease nsp11 belongs to the XendoU superfamily and plays a crucial role in arterivirus replication. Here, we report the first crystal structure of the arterivirus nsp11 protein from PRRSV, which exhibits a unique structure and assembles into an asymmetric dimer whose structure is completely different from the hexameric structure of coronavirus nsp15. However, the structures of the PRRSV nsp11 and coronavirus nsp15 catalytic domains were perfectly superimposed, especially in the "active site loop" (His129 to His144) and "supporting loop" (Val162 to Thr179) regions. Importantly, our biochemical data demonstrated that PRRSV nsp11 exists mainly as a dimer in solution. Mutations of the major dimerization site determinants (Ser74 and Phe76) in the dimerization interface destabilized the dimer in solution and severely diminished endoribonuclease activity, indicating that the dimer is the biologically functional unit. In the dimeric structure, the active site loop and supporting loop are packed against one another and stabilized by monomer-monomer interactions. These findings may help elucidate the mechanism underlying arterivirus replication and may represent great potential for the development of antiviral drugs. IMPORTANCE The PRRSV nsp11 endoribonuclease plays a vital role in arterivirus replication, but its precise roles and mechanisms of action are poorly understood. Here, we report the first dimeric structure of the arterivirus nsp11 from PRRSV at 2.75-Å resolution. Structural and biochemical experiments demonstrated that nsp11 exists mainly as a dimer in solution and that nsp11 may be fully active as a dimer. Mutagenesis and structural analysis revealed NendoU active site residues, which are conserved throughout the order Nidovirales (families Arteriviridae and Coronaviridae) and the major determinants of dimerization (Ser74 and Phe76) in Arteriviridae. Importantly, these findings may provide a new structural basis for antiviral drug development. . 2016. A dimerization-dependent mechanism drives the endoribonuclease function of porcine reproductive and respiratory syndrome virus nsp11. J Virol 90:4579 -4592.

A:
A Dimerization-Dependent Mechanism Drives the Endoribonuclease Function of Porcine Reproductive and Respiratory Syndrome Virus nsp11
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