Objective To knockout Rag2 and IL2rg genes and construct severe combined immunodeficiency mice based on CRISPR/Cas9 technology. Method Design and synthesis of 25 bp sgRNA were made according to the Rag2 and IL2rg sequences in Genbank. After annealing, sgRNA was cloned into pX330 vector. Recombination plasmid Rag2?sgRNA, IL2rg?sgRN and Cas9 were then transcribed into RNA, these RNA were microinjected into zygotes and the zygotes were transplanted into recipient ICR mice. F0 founders were born and mutated F0 founders mated with wild type mice to obtain F1 generation heterozygous mice. Mutated F1 mice were crossed and got F2 generation homozygous mice. Genotype and phenotype of the knockout mice were identified by sequencing, flow cytometry and xenograft model. Results Rag2?sgRNA and IL2rg?sgRNA recombination plasmids were constructed and transcribed into RNA. After microinjection and mat? ing, F0 founders were born and F2 homozygous mice were obtained. The results of sequencing showed that there were two types of genotype in IL2rg gene, 10 bp or 11 bp deletion;however, there was only one genotype in Rag2 gene, which was 8 bp deletion. Compared with wild?type BALB/c mice, the number of CD3 +, B220 + and NKp46 + cells in peripheral blood of the knockout mice was reduced significantly. After inoculation of human breast cancer cell line SKBR?2HL cells, tumor size in the xenograft mouse model was increased gradually along with time extension. Conclusion CRISPR/Cas9 is an efficient way to mutate Rag2 and IL2rg gene in mice in vivo, leading to aberrant T cells, B cells and NK cells.

Objective:To explore the risk factors and prognosis of carbapenem-resistant Klebsiella pneumoniae (CRKP) infection for inpatients in hepatobiliary surgery. Methods:The clinical data of patients with Klebsiella pneumoniae infection admitted to the Department of Hepatobiliary Surgery, Hunan Provincial People's Hospital from January 2016 to December 2020 were retrospectively analyzed. For each patient with CRKP infection, two patients with non-carbapenem-resistant Klebsiella pneumoniae (non-CRKP) infection were selected for matching. A total of 720 patients with Klebsiella pneumoniae infection were involved, including 444 males and 276 females, aged (58.0±11.6) years old. According to the infection conditions, they were divided into two groups: CRKP group ( n=240) and non-CRKP group ( n=480). The 240 CRKP patients were divided into two subgroups according to their prognosis: death group ( n=34) and survival group ( n=206). The general information, laboratory test results, antibiotic use and infection outcomes of patients were recorded to analyze the risk factors of infection and death after infection. Results:Acute pancreatitis ( OR=3.473, 95% CI: 1.844-6.541), chronic cardiovascular disease before infection ( OR=2.028, 95% CI: 1.228-3.347), chronic renal failure ( OR=1.873, 95% CI: 1.142-3.073), hypoalbuminemia ( OR=3.060, 95% CI: 1.869-5.010), use of carbapenems ( OR=3.882, 95% CI: 2.518-5.985), admission to intensive care unit ( OR=1.783, 95% CI: 1.034-3.075) and surgery within 30 days before infection ( OR=13.463, 95% CI: 7.482-24.223) were independent risk factors for CRKP infection inpatients in hepatobiliary surgery(all P<0.05). Chronic respiratory disease before infection ( OR=3.784, 95% CI: 1.420-10.089), mechanical ventilation ( OR=5.085, 95% CI: 1.436-18.011), disturbance of consciousness ( OR=40.710, 95% CI: 3.564-464.943), hormone therapy ( OR=14.977, 95% CI: 3.819-58.743) and treatment of quinolone antibiotics ( OR=4.102, 95% CI: 1.226-13.726) were independent risk factors for death of inpatients with CRKP infection in hepatobiliary surgery (all P<0.05). The resistance of amikacin, tobramycin, ceftazidime, cefepime, aztreonam, ciprofloxacin, levofloxacin, co-sulfamethoxazole and piperacillin/tazobactamand in CRKP group were significantly different compared with non-CRKP group (all P<0.05). Conclusion:The occurrence of CRKP infection for inpatients in hepatobiliary surgery is related to various factors such as underlying diseases, antibiotic use and self-barrier destruction, and these factors affect the infection outcome of patients.