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.

Background: In last three years, 96 suspected poultry farms from different provinces in China were diagnosed for avian infectious bronchitis (IB) survey. Finally, 221 IBV strains were confirmed by dwarf embryo test and RT-PCR assay. By virus recovery trials, 187 of the isolates caused the birds died or distressed from nephritis, which was accordant with the clinical record. Results: Based on epidemiology analysis of recent field isolates of nephropathogenic IB in vaccinated farms in China, YL6 strain were used for vaccination and evaluated by antibody titer and challenge tests. The immunoprotection test indicated that the practical application of vaccine based on the recent field strains could finely facilitate controlling the nephropathogenic IB. Conclusions: Our study was aim at setting a guide for safeguard against nephropathogenic IBV-caused disease in China.
Epidemiology and immunoprotection of nephropathogenic avian infectious bronchitis virus in southern China