Advances of targeted protein degradation technology and its applications in diseases therapy / 生物工程学报

Targeted protein degradation (TPD) technology facilitates specific and efficient degradation of disease-related proteins through hijacking the two major protein degradation systems in mammalian cells: ubiquitin-proteasome system and lysosome pathway. Compared with traditional small molecule-inhibitors, TPD-based drugs exhibit the characteristics of a broader target spectrum. Compared with techniques interfere with protein expression on the gene and mRNA level, TPD-based drugs are target-specific, efficaciously rapid, and not constrained by post-translational modification of proteins. In the past 20 years, various TPD-based technologies have been developed. Most excitingly, two TPD-based therapeutic drugs have been approved by FDA for phase Ⅰ clinical trials in 2019. Despite of the early stage characteristics and various obstructions of the TPD technology, it could serve as a powerful tool for the development of novel drugs. This review summarizes the advances of different degradation systems based on TPD technologies and their applications in disease therapy. Moreover, the advantages and challenges of various technologies were discussed systematically, with the aim to provide theoretical guidance for further application of TPD technologies in scientific research and drug development.

Progress in interactions between rotavirus infection and innate immunity / 中华微生物学和免疫学杂志

Rotavirus (RV) is one of the leading causes of acute gastroenteritis in infants and young animals worldwide. Rotavirus infection has obvious species specificity and mainly causes diarrhea in infants and young animals. The host innate responses suppress the infection and replication of rotavirus through activating multiple signaling pathways. Meanwhile, rotavirus also antagonizes the innate immune responses in various ways. This article reviewed the mechanisms of host innate immune responses to rotavirus infection and the antagonistic mechanism of rotavirus against host innate immunity with a view to providing reference for the development of therapeutic drugs and the prevention of rotavirus infection.

Neutralizing and binding antibody kinetics of COVID-19 patients during hospital and convalescent phases

Knowledge of the host immune response after natural SARS-CoV-2 infection is essential for informing directions of vaccination and epidemiological control strategies against COVID-19. In this study, thirty-four COVID-19 patients were enrolled with 244 serial blood specimens (38.1% after hospital discharge) collected to explore the chronological evolution of neutralizing (NAb), total (TAb), IgM, IgG and IgA antibody in parallel. IgG titers reached a peak later (approximately 35 days postonset) than those of Nab, Ab, IgM and IgA (20[~]25 days postonset). After peaking, IgM levels declined with an estimated average half-life of 10.36 days, which was more rapid than those of IgA (51.25 days) and IgG (177.39 days). Based on these half-life data, we estimate that the median times for IgM, IgA and IgG to become seronegative are 4.59 (IQR 4.12-5.03), 7.78 (IQR 6.71-9.16) and 42.72 (IQR 33.75-47.96) months post disease onset. The relative contribution of IgM to NAb was higher than that of IgG (standardized {beta} regression coefficient: 0.53 vs 0.48), so the rapid decline in NAb may be attributed to the rapid decay of IgM in acute phase. However, the relative contribution of IgG to NAb increased and that of IgM further decreased after 6 weeks postonset. Its assumed that the decline rate of NAb might slow down to the same level as that of IgG over time. This study suggests that SARS-CoV-2 infection induces robust neutralizing and binding antibody responses in patients and that humoral immunity against SARS-CoV-2 acquired by infection may persist for a relatively long time.

Room-temperature-storable PCR Mixes for SARS-CoV-2 Detection

A novel coronavirus (severe acute respiratory syndrome coronavirus 2, SARS-CoV-2) emerged in late 2019, causing an outbreak of pneumonia [coronavirus disease 2019 (COVID-19)] in Wuhan, China, which then rapidly spread globally. Although the use of ready-made reaction mixes can enable more rapid PCR-based diagnosis of COVID-19, the need to transport and store these mixes at low temperatures presents challenges to already overburdened logistics networks. Here, we present an optimized freeze-drying procedure that allows SARS-CoV-2 PCR mixes to be transported and stored at ambient temperatures, without loss of activity. Additive-supplemented PCR mixes were freeze-dried. The residual moisture of the freeze-dried PCR mixes was measured by Karl-Fischer titration. We found that freeze-dried PCR mixes with [~]1.2% residual moisture are optimal for storage, transport, and reconstitution. The sensitivity, specificity, and repeatability of the freeze-dried reagents were similar to those of freshly prepared, wet reagents. The freeze-dried mixes retained activity at room temperature (18[~]25{degrees}C) for 28 days, and for 14 and 10 days when stored at 37{degrees}C and 56{degrees}C, respectively. The uptake of this approach will ease logistical challenges faced by transport networks and make more cold storage space available at diagnosis and hospital laboratories. This method can also be applied to the generation of freeze-dried PCR mixes for the detection of other pathogens.

Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease 2019

BackgroundThe novel coronavirus SARS-CoV-2 is a newly emerging virus. The antibody response in infected patient remains largely unknown, and the clinical values of antibody testing have not been fully demonstrated. MethodsA total of 173 patients with confirmed SARS-CoV-2 infection were enrolled. Their serial plasma samples (n = 535) collected during the hospitalization period were tested for total antibodies (Ab), IgM and IgG against SARS-CoV-2 using immunoassays. The dynamics of antibodies with the progress and severity of disease was analyzed. ResultsAmong 173 patients, the seroconversion rate for Ab, IgM and IgG was 93.1% (161/173), 82.7% (143/173) and 64.7% (112/173), respectively. Twelve patients who had not seroconverted were those only blood samples at the early stage of illness were collected. The seroconversion sequentially appeared for Ab, IgM and then IgG, with a median time of 11, 12 and 14 days, respectively. The presence of antibodies was < 40% among patients in the first 7 days of illness, and then rapidly increased to 100.0%, 94.3% and 79.8% for Ab, IgM and IgG respectively since day 15 after onset. In contrast, the positive rate of RNA decreased from 66.7% (58/87) in samples collected before day 7 to 45.5% (25/55) during days 15 to 39. Combining RNA and antibody detections significantly improved the sensitivity of pathogenic diagnosis for COVID-19 patients (p < 0.001), even in early phase of 1-week since onset (p = 0.007). Moreover, a higher titer of Ab was independently associated with a worse clinical classification (p = 0.006). ConclusionsThe antibody detection offers vital clinical information during the course of SARS-CoV-2 infection. The findings provide strong empirical support for the routine application of serological testing in the diagnosis and management of COVID-19 patients.

Research progress in signal amplification for immunoassays / 中华微生物学和免疫学杂志

With the requirements of early diagnosis, biomarker development and functional definition, the challenge of sensitivity of immunoassay has become increasingly prominent. How to improve it to break the bottleneck has become a major challenge in the field of bioassays. Amplifying the immunosignal is the most direct method to improve detection sensitivity. Biotin-avidin system (BAS), tyramide signal amplification (TSA) and immuno-polymerase chain reaction (Im-PCR) are the most classic signal amplification techniques which significantly improved the sensitivity of immunoassays. In recent years, studies have confirmed that the sensitivity of immunoassays can be further increased by approximately three orders of magnitude with the invention of techniques including catalyzed reporter deposition-based signal amplification, nanotechnologies-based signal amplification and hybridization chain reaction-based signal amplification. Herein, we will summarize the techniques that have been developed in recent years for amplifying the signals of immunodetection and comparatively analyze their advantages and disadvantages in order to provide reference for the developed techniques transformed to clinical application and further research on ultrasensitive immunoassays.

Polymerization and evaluation of the protective efficacy of rotavirus VP4* proteins / 生物工程学报

In previous studies, we found that truncated rotavirus VP4* (aa 26-476) could be expressed in soluble form in Escherichia coli and confer high protection against rotavirus in the mouse mode. In this study, we further improved the immunogenicity of VP4* by polymerization. The purified VP4* was polymerized through incubation at 37 ℃ for 24 h, and then the homogeneity of the particles was analyzed by HPLC, TEM and AUC, while the thermal stability and antigenicity was analyzed by DSC and ELISA, respectively. Finally, the immunogenicity and protective efficacy of the polymers analyzed by a mouse maternal antibody model. The results showed that VP4* aggregated into homogeneous polymers, with high thermostability and neutralizing antibody binding activity. In addition, VP4* polymers (endotoxin <20 EU/dose) stimulated higher neutralizing antibodies and confer higher protection against rotavirus-induced diarrhoea compared with the VP4* trimers when immunized with aluminium adjuvant. In summary, the study in VP4* polymers provides a new strategy for the development of recombinant rotavirus vaccines.

Advances in reverse genetics systems for rotavirus / 中华微生物学和免疫学杂志

Reverse genetics approaches can directly manipulate the genome of virus at the gene level, making it possible to quickly, directly and thoroughly study the mechanisms of virus replication and pathogenesis. At present, many viruses of the family Reoviridae, such as mammalian orthoreovirus ( MRV) and bluetongue virus ( BTV) , have made great progress in basic viral research using the powerful tool of re-verse genetics. However, for members of the genus Rotavirus in the family Reoviridae, progress in the con-struction of reverse genetic systems has been slow. The remarkable reverse genetics system based on helper-viruses was established in 2006, and it was not until 2017 that the entirely plasmid-based reverse genetics system was successfully established. This paper briefly reviewed the development of reverse genetics systems for rotavirus and prospected the direction for future research in order to provide technical support for acceler-ating the basic research on mechanisms of rotavirus infection.

Research progress in laboratory detection of cytomegalovirus and its feasibility analysis for neonatal screening / 临床儿科杂志

Most of the human cytomegalovirus (HCMV) infection has no obvious clinical symptoms, but it can be latent for life and activated under specific conditions. HCMV active infection during pregnancy can lead to abortion, stillbirth, birth-defect and so on, which causes serious economic and social burdens. Both primary and secondary HCMV infection can lead to congenital infection of newborn, but there is still no effective method for the screening of HCMV secondary infection during pregnancy currently. Therefore, a comprehensive congenital HCMV screening for newborns is implemented for early intervention and thus reducing the consequences of congenital HCMV infection. In this paper, the methods of HCMV laboratory detection and its feasibility for neonatal screening are analyzed, in order to provide a basis for the selection of methods in neonatal congenital HCMV screening.

Establishment and validation of an enzyme-linked immunosorbent assay for IgG antibody against cytomegalovirus based on pp150 antigen.

The development of HCMV vaccines for the prevention of congenital HCMV has been identified as a top priority by the Institute of Medicine (USA), and virus infection is an important endpoint for the efficacy evaluation of the candidate vaccines. However, it is technically difficult to capture the HCMV viremia or uremia in infected individuals because the viremia or uremia can be detected only transiently during acute infection, and most people who are infected are asymptomatic. Thus, it is much desired to develop a serological assay for effectively distinguishing anti-HCMV antibodies as a result of natural infection from those elicited by subunit antigen vaccination. In this study, five HCMV proteins other than antigens commonly used as subunit vaccine candidates were expressed in Escherichia coli and purified, and out of them, the HCMV tegument protein pp150 exhibited the most robust reactivity to seropositive sera and the faintest cross reaction to seronegative sera. With a coefficient of variability less than 15%, an ELISA based on pp150 antigen (pp150-ELISA) showed 100% (366/366) sensitivity and 100% (77/77) specificity (using neutralizing activity as a gold standard) and good quantitative correlation with an in-house ELISA based on virus lysate antigens. Taken together, these results indicate that pp150-ELISA, which has comparable performance to generally used assays based on virus lysate antigens, might provide a simple method to detect HCMV infection or reactivation and could be useful in future HCMV subunit vaccine efficacy trials.

Research progress in rotavirus VP4 subunit vaccine / 生物工程学报

Rotaviruses are leading causes of worldwide acute diarrhea in children younger than 5 years old, with severe consequence of social and economic burden. Vaccination is the most effective way to control rotavirus infection, however, the licensed rotavirus vaccines are ineffective in some low-income countries of Africa and Asia, where the mortality caused by rotavirus is higher than other areas. In addition, there are also safety concerns such as increased risk of intussusception. Therefore, it is urgent to improve the efficiency and safety of rotavirus vaccine to reduce the morbidity and mortality caused by rotavirus. Till now, many efforts are made to improve the effectiveness of rotavirus vaccines, and the inactive vaccine becomes the main trend in the research of rotavirus vaccine. The developments in recombinant rotavirus vaccines, especially in VP4 subunit vaccines are summarized in this review, and it could be helpful to develop effective recombinant rotavirus vaccines in further studies.

Impact of maternal antibodies on protective efficacy of rotavirus vaccine:a review / 中华微生物学和免疫学杂志

Rotavirus is one of the most common causes of gastroenteritis among children under five years of age worldwide. Most children are infected with rotavirus in their early childhood. Currently, no ef-fective treatment is available for diarrhea caused by rotavirus infection, and vaccination is the most effective way to prevent rotavirus infection. With the introduction of rotavirus vaccines, the morbidity and mortality of severe diarrhea in children caused by rotavirus infection are declined significantly, but these rotavirus vac-cines have significantly lower efficacy in developing countries in Africa and some countries in Asia where the mortality of rotavirus-related diseases is high than in developed countries. High titers of maternal antibodies may be one of the reasons why the efficacy of rotavirus vaccines is low in these countries. Extensive studies have been conducted on the relationship between neonatal response to rotavirus vaccine immunization and ro-tavirus-specific antibodies in the mother′s milk and serum in recent years. However, results of some studies are in conflict. In this review, we summarize the relationship between maternal antibodies and the immune responses after vaccination with rotavirus vaccines in order to provide basis for improving the efficacy of rota-virus vaccines in low-income countries.

Impact of maternal antibodies on protective efficacy of rotavirus vaccine:a review / 中华微生物学和免疫学杂志

Rotavirus is one of the most common causes of gastroenteritis among children under five years of age worldwide. Most children are infected with rotavirus in their early childhood. Currently, no ef-fective treatment is available for diarrhea caused by rotavirus infection, and vaccination is the most effective way to prevent rotavirus infection. With the introduction of rotavirus vaccines, the morbidity and mortality of severe diarrhea in children caused by rotavirus infection are declined significantly, but these rotavirus vac-cines have significantly lower efficacy in developing countries in Africa and some countries in Asia where the mortality of rotavirus-related diseases is high than in developed countries. High titers of maternal antibodies may be one of the reasons why the efficacy of rotavirus vaccines is low in these countries. Extensive studies have been conducted on the relationship between neonatal response to rotavirus vaccine immunization and ro-tavirus-specific antibodies in the mother′s milk and serum in recent years. However, results of some studies are in conflict. In this review, we summarize the relationship between maternal antibodies and the immune responses after vaccination with rotavirus vaccines in order to provide basis for improving the efficacy of rota-virus vaccines in low-income countries.