The research on the immunoregulatory effect of programmed death-1 (PD-1) in infectious diseases mainly focuses on chronic viral infection, but there are few studies on acute viral infection. In chronic viral infection, PD-1 is highly expressed on the surface of CD8+ T cells, which is a sign of CD8+ T cell depletion. Recent studies have shown that in chronic viral infection, PD-1 is also highly expressed on the surface of regulatory T cells and binds to programmed death-ligand 1 (PD-L1) on the surface of exhausted CD8+ T cells, resulting in a stronger inhibitory effect on CD8+ T cell immunity. Blocking the PD-1/PD-L1 signaling pathway between exhausted CD8+ T cells and regulatory T cells can significantly reverse the depletion of CD8+ T cells and greatly improve the antiviral effect of CD8+ T cells. However, the role of the PD-1/PD-L1 signaling pathway in acute viral infection remains unknown. This article summarizes the latest research on PD-1 in infectious diseases and discusses its role in acute and chronic viral infection.

Objective The aim of this study was to investigate the value of detection of serum antibody of EV71-IgM in early diagnosis for hand foot and mouth disease (HFMD) by EV71 infection.Methods A total of 436 cases of children clinically diagnosed with HFMD from April to October 2014 and April to October 2016 in Guangxi were studied.All the serums were tested for EV71-IgM.Throat swabs or anal swabs were collected from 136 cases of 436 children to detect viral nucleic acid by fluorescence quantitative RT-PCR.All data were analyzed with SPSS 17.0.Results Among 436 cases of clinical diagnosed HFMD,256 cases were EV71-IgM antibody positive,while 180 cases were negative.The positive rate of EV71-IgM antibody in fatal group and severe group was significantly higher than that in mild group (x2=88.016,P＜0.001).The fluorescent quantitative RT-PCR was used as the standard.In 136 cases,comparing the EV71-RNA detected from throat swabs or anal swabs with EV-IgM detected from serum,the detection consistency of the two methods was moderately reliable (Kappa=0.575,P＜0.001),the sensitivity of EV71-IgM detection was 93.67％(74 /79),the specificity was 61.40％ (35/57).The positive rate of EV71-IgM antibody was gradually increased in the course of 1-3 days after the onset.The detection rate was 92.31％ in the third days,and the detection rate was 100％ in the course of 4-10 days after the onset.Conclusion Rapid detection of serum EV71-IgM antibody had good application value,providing a high sensitivity and convenient operation way for early diagnosis of EV71 infection.

Objective:To investigate the etiological characteristics of 319 cases of hand foot mouth disease (HFMD).Methods:A total of 319 children diagnosed with HFMD from January 2014 to January 2016 in Guangxi were collected and divided into three groups:fatal group (85 9ases),severe group (132 cases) and mild group (102 cases).Serum EV71-IgM antibody and CVA16-IgM antibody were detected with enzymelinked immunosorbent assay (ELISA).Results:The positive rate of EV71-IgM antibody in the fatal group and severe group were significantly higher than that in the mild group (P ＜0.05).The positive rate of EV71-IgM antibody in death cases was 85.71 ％.The positive rate of CVA16-IgM antibody in mild group was significantly higher than those in the fatal group and severe group (P ＜0.05).There was no significant difference on the gender ratio and age composition among EV71-IgM antibody positive cases,CVA16-IgM antibody positive cases,EV71-IgM antibody and CVA16-IgM antibody double positive cases,EV71-IgM antibody and CVA16-IgM antibody double negative cases (P ＞0.05).Conclusion:The etiology analysis revealed that severe and fatal HFMD were mainly caused by EV71.Meanwhile,we need to pay attention to the possibility that CVA16 and other enteroviruses infected cases developing into severe ones.