To achieve efficient and rapid detection of duck astrovirus type 2(DAstV-2),RPA prim-ers and crRNA were designed and synthesized based on the conserved sequence of the ORF2 gene of DAstV-2.A detection method for DAstV-2 was constructed,integrating RPA nucleic acid ampli-fication,LwCas13a cleavage,and colloidal gold lateral flow dipstick visualization.The specificity,sensitivity,and concordance of this detection method were evaluated.The experimental results showed that the detection limit for the DAstV-2 recombinant plasmid standard was 1.2×101 cop-ies/μL,which is superior to the conventional RT-PCR method.The method can specifically detect DAstV-2 pathogenic nucleic acids without cross-reactivity with DAstV-1,DAstV-3,DAstV-4,duck plague virus(DEV),and duck tembusu virus(DTMUV).When testing liver tissue samples from ducks suspected of being infected with DAstV-2,the results obtained using this method were com-pletely consistent with those from real-time quantitative PCR,with a 100％concordance rate.How-ever,this method is simpler and faster to perform.The research indicates that the established RPA-CRISPR/Cas13a-LFD detection system has high sensitivity,strong specificity,and high accuracy,capable of completing rapid visual detection of DAstV-2 nucleic acids within 1 h at a constant tem-perature of 37 ℃,providing a new technical platform for the rapid diagnosis of DAstV-2.

To achieve efficient and rapid detection of duck astrovirus type 2(DAstV-2),RPA prim-ers and crRNA were designed and synthesized based on the conserved sequence of the ORF2 gene of DAstV-2.A detection method for DAstV-2 was constructed,integrating RPA nucleic acid ampli-fication,LwCas13a cleavage,and colloidal gold lateral flow dipstick visualization.The specificity,sensitivity,and concordance of this detection method were evaluated.The experimental results showed that the detection limit for the DAstV-2 recombinant plasmid standard was 1.2×101 cop-ies/μL,which is superior to the conventional RT-PCR method.The method can specifically detect DAstV-2 pathogenic nucleic acids without cross-reactivity with DAstV-1,DAstV-3,DAstV-4,duck plague virus(DEV),and duck tembusu virus(DTMUV).When testing liver tissue samples from ducks suspected of being infected with DAstV-2,the results obtained using this method were com-pletely consistent with those from real-time quantitative PCR,with a 100％concordance rate.How-ever,this method is simpler and faster to perform.The research indicates that the established RPA-CRISPR/Cas13a-LFD detection system has high sensitivity,strong specificity,and high accuracy,capable of completing rapid visual detection of DAstV-2 nucleic acids within 1 h at a constant tem-perature of 37 ℃,providing a new technical platform for the rapid diagnosis of DAstV-2.

Objective To explore the repair result of full-thickness cartilage defects in diannan small-ear pig by bone mesenchymal stem cells (BMSCs) transferred with both transforming growth factor-β3(TGF-β3) and bone morphogenetic protein-2(BMP-2) gene mediated by adenovirus vector and combined with deminerized bone matrix (DBM). Methods 32 full-thickness defects from 16 knees of 8 pigs were randomly divided into 4 groups in the experiments. In group A, the animals′ lateral femoral condyle of right knee joint was repaired with DBM and BMSC infected with both Ad-TGF-β3 and Ad-BMP-2. In group B, the medial femoral condyle of right knee joint was repaired with DBM and BMSC without infection. In group C, the lateral femoral condyle of left knee joint was repaired with DBM. And the group D is control group. Morphology and histology were observed 2, 4, 8 and 12 weeks after operation. Results 12 weeks after operation, the whole defects were repaired in group A, HE staining showed typical cartilaginous structure in the repaired area. In group D, defects were not repaired but filled with fibrous tissue. The O′driscoll scores were 15.65 ± 0.11 (group A), 11.33 ± 0.22 (group B), 6.13 ± 0.15 (group C) and 5.08 ± 0.15 (group D). There was significant difference among the groups (P < 0.05). Conclusions The new type of tissue engineering scaffold that DBM combined with BMSCs transfected with both Ad-BMP-2 and Ad-TGF-β3 could induce cartilage regeneration and repair the defects.

Objective To explore the enhancement effect of N-trimethyl chitosan(TMC) on transdermal absorption of 8-methoxypsoralen-loaded liposomal(LMOP) gels in vitro.Methods TMC with quaternization degree of 60％ (TMC60) as the enhancer,the LMOP gels were prepared with free TMC60 or TMC60-coating.The enhancement of free TMC60 or TMC60-coating was studied by using Franz diffusion,cells with LMOP gels as the negative control and LMOP gels including 1％ Azone + propylene glycol as the positive control.Results Compared with the negative control,enhancement and drug amount in skin of LMOP gels with enhancer all showed significant difference (x2 =8.65,P ＜ 0.05),and the free TMC.60 was the best.Conclusion TMC can enhance the transdermal penetration of LMOP gels in vitro and is valuable to be studied further.