An in-depth investigation of the safety and immunogenicity of an inactivated SARS-CoV-2 vaccine

BACKGROUNDIn-depth investigations of the safety and immunogenicity of inactivated SARS-CoV-2 vaccines are needed. METHODIn a phase I randomized, double-blinded, and placebo-controlled trial involving 192 healthy adults 18-59 years of age, two injections of three different doses (50 EU, 100 EU and 150 EU) of an inactivated SARS-CoV-2 vaccine or the placebo were administered intramuscularly with a 2- or 4-week interval between the injections. The safety and immunogenicity of the vaccine were evaluated within 28 days. FINDINGIn this study, 191 subjects assigned to three doses groups or the placebo group completed the 28-day trial. There were 44 adverse reactions within the 28 days, most commonly mild pain and redness at the injection site or slight fatigue, and no abnormal variations were observed in 48 cytokines in the serum samples of immunized subjects. The serum samples diluted from 1:32 to 1:4096 and incubated with the virus did not show antibody-dependent enhancement effects (ADEs) with regard to human natural killer cells, macrophages or dendritic cells. At day 14, the seroconversion rates had reached 92%, 100% and 96% with geometric mean titers (GMTs) of 18.0, 54.5 and 37.1, and at day 28, the seroconversion rates had reached 80%, 96% and 92% with GMTs of 10.6, 15.4 and 19.6in 0, 14 and 0, 28 procedures, respectively. Seroconversion was associated with the synchronous upregulation of ELISA antibodies against the S protein, N protein and virion and a cytotoxic T lymphocyte (CTL) response. Transcriptome analysis shaped the genetic diversity of immune response induced by the vaccine. INTERPRETATIONIn a population aged 18-59 years, this inactivated SARS-CoV-2 vaccine was safe and immunogenic. Trial registrationNCT04412538 FUNDINGThe National Key R&D Program of China (2020YFC0849700), the Program of Chinese Academy of Medicine Science and the Major Science and Technology Special Projects of Yunnan Province.

A valid protective immune response elicited in rhesus macaques by an inactivated vaccine is capable of defending against SARS-CoV-2 infection

With the relatively serious global epidemic outbreak of SARS-CoV-2 infection, public concerns focus on not only clinical therapeutic measures and public quarantine for this disease but also the development of vaccines. The technical design of our SARS-CoV-2 inactivated vaccine provides a viral antigen that enables the exposure of more than one structural protein based upon the antibody composition of COVID-19 patients convalescent serum. This design led to valid immunity with increasing neutralizing antibody titers and a CTL response detected post-immunization of this vaccine by two injections in rhesus macaques. Further, this elicited immunoprotection in macaques enables not only to restrain completely viral replication in tissues of immunized animals, compared to the adjuvant control and those immunized by an RBD peptide vaccine, but also to significantly alleviate inflammatory lesion in lung tissues in histo-pathologic detection, compared to the adjuvant control with developed interstitial pneumonia. The data obtained from these macaques immunized with the inactivated vaccine or RBD peptide vaccine suggest that immunity with a clinically protective effect against SARS-CoV-2 infection should include not only specific neutralizing antibodies but also specific CTL responses against at least the S and N antigens.

Pathogenesis of nasal and genital infection with herpes simplex virus type Ⅱ in BALB/c mice / 中华微生物学和免疫学杂志

Objective To observe and analyze the pathological changes in BALB/c mice infected with herpes simplex virus typeⅡ (HSV-2) through nasal and genital inoculation. Methods Six-week old female BALB/c mice were divided into two groups, experimental and control groups. In the experimental group, the mice were infected with HSV-2 (104 CCID50/20μl per mouse) through nasal and genital tract in-oculation. Accordingly, the mice in the control group were injected with equal volume of PBS. Tissue speci-mens were collected from lung, nervous system and reproductive system for pathological analysis and viral load detection at different time points after infection. Lat gene expression in mouse trigeminal and sacral gan-glia was detected through in situ hybridization. In addition, the proliferation of viruses isolated form trigemi-nal and sacral ganglia of the infected mice was observed in vitro. Results Weight loss and histopathological lesions were observed in the mice of the experimental group 6 d after infection. Major pathological changes in the HSV-2-infected mice through nasal tract inoculation involved the lung and central nervous system( CNS) , including alveolar wall congestion, cerebrovascular cuff response and lymphocyte infiltration. How-ever, the major lesions in the infected mice through genital tract inoculation were found in the reproductive ducts, such as sacral ganglion necrosis, eosinophilia in the vagina and uterus, and ovarian congestion. Re-sults of the viral load detection in tissues and organs of the infected mice were consistent with the pathological changes. The mice infected through nasal tract inoculation had significantly higher viral loads in the nerves and lungs than those by genital tract inoculation, but lower viral loads in the genital tracts and sacral ganglia. Positive expression of lat gene at mRNA level was detected in the trigeminal and sacral ganglia of mice with HSV-2 latency 28 d after infection. In addition, both of the tissue fragments from trigeminal and sacral ganglia had cytopathic effects ( CPEs) on Vero cells. Enhanced expression of lat gene at mRNA level and much severer CPEs were induced by genital tract inoculation than by nasal tract inoculation. Conclu-sions HSV-2 could infect and cause histopathological damages in BALB/c mice through both nasal and genital tracts. In addition, the locations of the pathological lesions were closely related to the mode of infection.

Expression characteristics of signaling molecules associated with innate immune response induced by HSV1 and HSV2 in respiratory and vaginal epithelial cells / 中华微生物学和免疫学杂志

Objective To investigate the influences of herpes simplex virus 1 and 2 ( HSV1 and HSV2) infection on the expression of signaling molecules associated with innate immune response in respira-tory and vaginal epithelial cells for bettering understanding of HSV infection and pathological characteristics in the primary infection site, namely mucosal epithelial tissues. Methods KMB17 and VK2 cells were in-fected with HSV. Changes in cell morphology and inner structure after HSV infection were observed under optical microscope and scanning electron microscope, respectively. Viral proliferation in KMB17 and VK2 cells was detected by plaque assay, microcytopathic assay and real-time quantitative PCR. Expression of sig-naling molecules associated with innate immune response in virus-infected KMB17 and VK2 cells were ana-lyzed by real-time quantitative PCR. Results Both HSV1 and HSV2 could infect KMB17 and VK2 cells, and cause damage to cell morphology and inner structure after 12 hours. Both of the two viruses formed simi-lar plaque on the single layer of KMB17 and VK2 cells, although HSV2 proliferated slower than HSV1. There were differences in the expression of signaling molecules associated with innate immune response in-duced by the two viruses in KMB17 and VK2 cells. Conclusion Both HSV1 and HSV2 could infect and proliferate in epithelial cells ( KMB17 and VK2 cells) . Although there were slight differences in viral prolif-eration between them, significant differences in the expression of signaling molecules associated with innate immune response induced by the two viruses were observed.