Human influenza A virus (IAV) is a major cause of life-threatening respiratory tract disease worldwide. Defensins are small cationic peptides of about 2-6 kDa that are known for their broad-spectrum antimicrobial activity. Here, we focused on the anti-influenza A activity of mouse beta-defensin 2 (mBD2). The prokaryotic expression plasmid pET32a-mBD2 was constructed and introduced into Escherichia coli Rosseta gami (2) to produce recombinant mBD2 (rmBD2). Purified rmBD2 showed strong antiviral activity against IAV in vitro. The protective rate for Madin-Darby canine kidney cells was 93.86% at an rmBD2 concentration of 100 microg/ml. Further studies demonstrated that rmBD2 prevents IAV infection by inhibiting viral entry. In addition, both pretreatment and postinfection treatment with rmBD2 provided protection against lethal virus challenge with IAV in experimental mice, with protection rates of 70 and 30%, respectively. These results suggest that the mBD2 might have important effects on influenza A virus invasion.

Background High-risk population of blood donation increases the prevalence of transmit blood-borne diseases and harm the blood safety. Syphilis accounts for approximately 10% of commonly sexually transmitted diseases. The risk factors for blood donors infected with syphilis are also risk factors for other blood borne diseases. The objective of the study is to investigate the seroprevalence and risk factors on syphilis among blood donors, and analyze the donation status of high-risk population. Methods A retrospective study was conducted in Chengdu Blood Center during 2005 and 2017. Serological test results of volunteer blood donors were collected. Conditional logistic regression models were performed to investigate syphilis-related risk factors and population attributable risk (PAR) was performed to predict the tendencies of high-risk populations’ on risky behaviors. Results The serological epidemic for syphilis among blood donors in Chengdu showed an upward trend from 2005 to 2017.TP positive blood donors were more likely to have multiple sexual partners and commercial sex (50.6% vs.22.6, 11.1% vs.4.6%). Multiple condition logistic regression model denoted the following risk factors for increasing rates of syphilis infections: multiple sexual partners (OR = 7.1, 95% CI:1.72–6.58), razor reuse (OR = 1.7;, 95% CI:1.01–2.01); ear piercing (OR = 2.7, 95% CI:1.48–3.37); tattoo (OR = 3.3, 95% CI:1.17–6.78); condom occasionally (OR = 2.8, 95% CI:0.68–1.66). The PAR for each of the risk factors were 0.225, 0.144, 0.147, 0.018, 0.129, 0.018, respectively. Conclusion Health consultation and screening of high-risk groups before blood donation need to be further improved. Blood donor recruitment should emphasize on excluding the high-risk donors and recruiting more low-risk blood donors. In addition, this study also shows that sharing cosmetic surgical instrument has been proven to transmit blood-borne diseases. Therefore, the syphilis in blood circulation should not be ignored. Electronic supplementary material The online version of this article (10.1186/s12879-019-4128-7) contains supplementary material, which is available to authorized users.

Influenza (flu) pandemics have presented a threat to human health in the past century. Because of outbreaks of avian flu in humans in some developing countries in recent years, humans are more eager to find a way to control flu. Mammalian beta-defensins (beta-defensins) are associated primarily with mucosal and skin innate immunity. Previous studies have demonstrated antimicrobial properties of a variety of defensin peptides. We have identified the presence of mouse beta-defensin 1, 2, and 3 genes (Mbd-1, 2, and 3) in trachea and lung tissues by RT-PCR before and after infection with influenza virus. We constructed a eukaryotic expression plasmid containing Mbd-3, pcDNA 3.1(+)/MBD-3, and the plasmid was introduced into Madin-Darby canine kidney (MDCK) cells by transfection. The expression of Mbd-3 in MDCK cells was verified by immunofluorescence test, RT-PCR, and Western blot. The pcDNA 3.1(+)/MBD-3 plasmid was injected into mice to observe its effect against influenza A virus (IAV) in vivo. Mouse beta-defensin genes could be expressed in trachea and lung tissues before IAV infection, but expression of Mbd-2 and Mbd-3 was increased significantly after IAV infection. The survival rate of mice with MBD-3 against IAV challenge was 71.43%, and MDCK cells with MBD-3 could clearly inhibit IAV replication. The results demonstrated that mouse beta-defensins possess anti-influenza virus activity, suggesting that mouse beta-defensins might be used as agents to prevent and treat influenza.

Background. Human umbilical cord mesenchymal stem cells (UC-MSCs) can regulate the function of immune cells. However, whether and how UC-MSCs can modulate the function of Vγ9Vδ2 T cells has not been fully understood. Methods. The PBMCs or Vγ9Vδ2 T cells were activated and expanded with pamidronate (PAM) and interleukin-2 (IL-2) with or without the presence UC-MSCs. The effects of UC-MSCs on the proliferation, cytokine expression, and cytotoxicity of Vγ9Vδ2 T cells were determined by flow cytometry. The effects of UC-MSCs on Fas-L, TRAIL-expressing Vγ9Vδ2 T cells, and Vγ9Vδ2 T cell apoptosis were determined by flow cytometry. Results. UC-MSCs inhibited Vγ9Vδ2 T cell proliferation in a dose-dependent but cell-contact independent manner. Coculture with UC-MSCs reduced the frequency of IFNγ+ but increased granzyme B+ Vγ9Vδ2 T cells. UC-MSCs inhibited the cytotoxicity of Vγ9Vδ2 T cells against influenza virus H1N1 infected A549 cells and also reduced the frequency of Fas-L+, TRAIL+ Vγ9Vδ2 T cells but failed to modulate the apoptosis of Vγ9Vδ2 T cells. Conclusions. These results indicated that UC-MSCs efficiently suppressed the proliferation and cytotoxicity of Vγ9Vδ2 T cells and modulated their cytokine production. Fas-L and TRAIL were involved in the regulation. Cell contact and apoptosis of Vγ9Vδ2 T cells were not necessary for the inhibition.

Mouse beta defensin-1 (mBD-1) is a cationic 37-amino acid antimicrobial peptide with three conserved cysterine disulfied bonds. It exhibits a broad antimicrobial spectrum, but mBD-1 against Candida albicans (C. albicans) and Cryptococcus neoformans (C. neoformans) is poorly understood. This study describes the mBD-1 gene, the heterologous fusion expression of the peptide in Escherichia coli, and the bioactive assay of released mature mBD-1. By constructing the expression plasmid (pET32a-mBD1), high yields of soluble mBD-1 fusion protein (0.67 g/L) could be obtained in E. coli and cleaved by enterokinase. The digested product was further purified and desalted with the final amount of pure mature mBD-1 being 0.14 g/L. Classical fungi growth inhibition assay showed clear antifungal activity against C. albicans and C. neoformans with IC(50) of 5 and 2 microM, respectively. The results show that the mBD-1 control fungal colonization through hyphal induction, direct fungicidal activity, and the activity is suppressed by increasing NaCl concentration. Successful expression of the mBD-1 peptide in E. coli offers a basis for further studying its antifungal mechanisms and may provide significance in developing this peptide to an antifungal drug.