Objective The feasibility of predicting the B-cell epitopes of human Neutrophil Gelatinase-Associated Lipocalin (NGAL) was discussed by applicating bioinformatics technology.Linear epitope molecules that have diagnostic value were screened and these recombinant linear multi-epitope peptides were constructed,and expressed.The immunogenicity of the recombinant linear multi-epitope peptides were also identified.Methods NGAL amino acid sequence was got from GenBank in the Department of Clinical Laboratory of the Second Affiliated Hospital of Nanjing Medical University in July 2015,the Predicted,ABCpred,BepiPred,BcePred,and Lasergene softwares were used to predict the linear B cell epitope prediction.The predict epitopes were constructed and prokaryotic expressed,and then the single epitope antigens which could reacted with commercially available polyclonal NGAL antibody were screened out by Western blot.Finally,the multi-epitope peptide was constructed,expressed,and identified through immunoreactions.Results Eight possible epitopes were obtained after prediction.pET32a-N1-N8 prokaryotic expression vector were used to express the predict epitopes.After purification and Western blot analysis,three of the epitopes have strong antigenicity,and then a soluble fusion protein was expressed and obtained from the multi-epitope prokaryotic expression vector pET22b-Ngal_MEP1.The fusion protein was successfully purified by Ni2 + affinity column.Western blot analysis showed that the fusion protein had a strong antigenicity.Conclusions The constructed multi-epitope linear NGAL antigen peptides can obtain high soluble expression in prokaryotic expression system,and have a strong immunoreactivity,which can be used in subsequent antibody preparation.

Objective To analyze the characteristics and epidemic trends of Mycoplasma pneumoniae(MP)infection among the pa-tients in our hospital,and explore the diagnostic values of interleukin-6(IL-6)and procalcitonin(PCT)detection for MP infection.Methods A retrospective analysis was conducted on the test results of MP nucleic acid and clinical data,including age,gender,sam-pling date,and treatment category of the 1 122 pneumonia patients in our hospital from September 1,2022,to August 31,2023.The positive detection rate of MP nucleic acid was analyzed in different genders,ages,visit categories,and seasons.Receiver operating characteristic(ROC)curves were plotted to analyze the diagnostic value of IL-6 and PCT levels,and their ratio values in Mycoplasma pneumoniae pneumonia(MPP).Results Among the 1 122 pneumonia patients,the overall positive detection rate of MP was 24.96％.The positive detection rates of MP nucleic acid in male and female patients were 23.28％and 27.29％,respectively,with no statistical-ly significant difference(P＞0.05).The median age of MP nucleic acid-negative patients was 37 years,while that of MP nucleic acid-positive patients was 7 years,showing a statistically significant difference(P＜0.01).MP nucleic acid-positive patients were mainly concentrated in the age groups of 1 to 2 years(20.37％),3 to 5 years(25.60％),and 6 to 8 years(67.40％).The positive detection rates of MP nucleic acid among 913 inpatients and 209 outpatients were 22.45％and 35.89％,respectively,with statistically significant difference(P＜0.01).The highest MP nucleic acid positive detection rate was observed in autumn(42.47％).MP could be co-infected with five other respiratory pathogens in which human rhinovirus(HRV)was the most common(17 cases).ROC curve analysis showed that the IL-6/PCT ratio had the best diagnostic performance for MP infection in the patients with all ages,with an area under the curve(AUCROC)of 0.746,superior to IL-6 and PCT alone.For MP-susceptible patients aged 6 to 8 years,IL-6 had the highest predictive value for MP infection,with an AUCROC of 0.767.Conclusions MPP tends to be epidemic in autumn,with children aged 6 to 8 years being the main susceptible population.The IL-6/PCT ratio is expected to become an auxiliary diagnostic and prognostic evaluation indi-cator for MPP.IL-6 levels have the highest predictive value for MP infection in the susceptible population.