The Chimeric Chaoyang-Zika Vaccine Candidate Is Safe and Protective in Mice.

Zika virus (ZIKV) is an emerging flavivirus that causes congenital syndromes including microcephaly and fetal demise in pregnant women. No commercial vaccines against ZIKV are currently available. We previously generated a chimeric ZIKV (ChinZIKV) based on the Chaoyang virus (CYV) by replacing the prME protein of CYV with that of a contemporary ZIKV strain GZ01. Herein, we evaluated this vaccine candidate in a mouse model and showed that ChinZIKV was totally safe in both adult and suckling immunodeficient mice. No viral RNA was detected in the serum of mice inoculated with ChinZIKV. All of the mice inoculated with ChinZIKV survived, while mice inoculated with ZIKV succumbed to infection in 8 days. A single dose of ChinZIKV partially protected mice against lethal ZIKV challenge. In contrast, all the control PBS-immunized mice succumbed to infection after ZIKV challenge. Our results warrant further development of ChinZIKV as a vaccine candidate in clinical trials.

Rapid Generation of Recombinant Flaviviruses Using Circular Polymerase Extension Reaction.

The genus Flavivirus is a group of arthropod-borne single-stranded RNA viruses, which includes important human and animal pathogens such as Japanese encephalitis virus (JEV), Zika virus (ZIKV), Dengue virus (DENV), yellow fever virus (YFV), West Nile virus (WNV), and Tick-borne encephalitis virus (TBEV). Reverse genetics has been a useful tool for understanding biological properties and the pathogenesis of flaviviruses. However, the conventional construction of full-length infectious clones for flavivirus is time-consuming and difficult due to the toxicity of the flavivirus genome to E. coli. Herein, we applied a simple, rapid, and bacterium-free circular polymerase extension reaction (CPER) method to synthesize recombinant flaviviruses in vertebrate cells as well as insect cells. We started with the de novo synthesis of the JEV vaccine strain SA-14-14-2 in Vero cells using CPER, and then modified the CPER method to recover insect-specific flaviviruses (ISFs) in mosquito C6/36 cells. Chimeric Zika virus (ChinZIKV) based on the Chaoyang virus (CYV) backbone and the Culex flavivirus reporter virus expressing green fluorescent protein (CxFV-GFP) were subsequently rescued in C6/36 cells. CPER is a simple method for the rapid generation of flaviviruses and other potential RNA viruses. A CPER-based recovery system for flaviviruses of different host ranges was established, which would facilitate the development of countermeasures against flavivirus outbreaks in the future.

Lasting antibody and T cell responses to SARS-CoV-2 in COVID-19 patients three months after infection.

The dynamics, duration, and nature of immunity produced during SARS-CoV-2 infection are still unclear. Here, we longitudinally measured virus-neutralising antibody, specific antibodies against the spike (S) protein, receptor-binding domain (RBD), and the nucleoprotein (N) of SARS-CoV-2, as well as T cell responses, in 25 SARS-CoV-2-infected patients up to 121 days post-symptom onset (PSO). All patients seroconvert for IgG against N, S, or RBD, as well as IgM against RBD, and produce neutralising antibodies (NAb) by 14 days PSO, with the peak levels attained by 15-30 days PSO. Anti-SARS-CoV-2 IgG and NAb remain detectable and relatively stable 3-4 months PSO, whereas IgM antibody rapidly decay. Approximately 65% of patients have detectable SARS-CoV-2-specific CD4+ or CD8+ T cell responses 3-4 months PSO. Our results thus provide critical evidence that IgG, NAb, and T cell responses persist in the majority of patients for at least 3-4 months after infection.

[Hyperactivation of c-Jun NH(2)-terminal protein kinase contributes to the proliferation of B lymphoma cells].

This study was purposed to explore the effect of hyperactivation of c-Jun NH(2)-terminal protein kinase (JNK) on the proliferation of B lymphoma cells. The human B lymphoma cell lines Daudi and Raji were chosen as research objects. The expression of JNK protein was determined by Western blot. The subcellular localization of JNK protein was detected by immunofluorescence. The cell cycle was analyzed by flow cytometry. The suppressive effect of JNK inhibitor SP600125 on the proliferation of Daudi and Raji cells was assayed by ATPLite method. The results demonstrated that hyperactivation of JNK has been found in Daudi and Raji cells. Immunofluorescence confirmed the aberrant subcellular localization of JNK protein in Daudi and Raji cells. Cell cycle assay revealed that Daudi and Raji cells underwent G(2)-M arrest in the presence of SP600125. Furthermore, Daudi and Raji cells showed significant increase in sub-G(1) population, an indicator of apoptotic cells, with the treatment of JNK inhibitors. These data suggested that JNK inhibitors suppressed the growth of B lymphoma cells via cell cycle arrest and apoptosis. Daudi and Raji cells treated with different concentrations of JNK selective inhibitor SP600125 showed dose-dependent reduction in the growth of Daudi and Raji cells. It is concluded that hyperactivation of JNK enhance the proliferation of Daudi and Raji cells. The aberrant subcellular localization of JNK protein may facilitate the nuclear accumulation of basal JNK activity, which made JNK to be a potential target to treat human B lymphoma.