Priming with SARS CoV S DNA and boosting with SARS CoV S epitopes specific for CD4+ and CD8+ T cells promote cellular immune responses

Vaccine
Volume 25, Issues 39–40, 28 September 2007, Pages 6981-6991

Jun Huang, Yingnan Cao, Jiali Du, Xianzhang Bu, Rui Ma, Changyou Wu.

Abstract

Cellular immune response plays an important role in antiviral immunity. In our previous study, immunization of mice with severe acute respiratory syndrome coronavirus (SARS CoV) spike (S) DNA vaccine could induce both humoral and cellular immunity in response to a pool of entire overlapping S peptides. Identification of functional dominant epitopes in SARS CoV S protein for T cells is crucial for further understanding of cellular immune responses elicited by SARS CoV S DNA vaccine. In present study, mice were immunized with SARS CoV S DNA vaccine. Subsequently, a pool of 17–19 mers overlapped SARS CoV S peptides, which served as immunogens, were scanned to identify the specific epitopes for T cells. Two H-2d restricted CD4+ T epitopes, N60 (S435–444) and P152 (S1111–1127), and two H-2d restricted CD8+ T cell epitopes, N50 (S365–374) and P141 (S1031–1047) were identified by three different methods, enzyme-linked immunosorbent assay (ELISA), enzyme linked immunospot assay (ELISPOT) and fluorescence activated cell sorter (FACS). The dominant CD4+ T cell epitope (N60) and CD8+ T cell epitope (N50) located in the receptor-binding domain (RBD) of SARS CoV S protein, which mediated virus combining and fusing to susceptible cells. Importantly, our novel finding is that mice primed with SARS S DNA vaccine and boosted with T cell epitopes (N50 and N60) could promote antigen specific CD4+ and CD8+ T cell immune responses. Our study provides valuable information for the design of vaccine for SARS study.

Keywords

SARS CoV, T cells, Epitope, Vaccines

Towards our understanding of SARS-CoV, an emerging and devastating but quickly conquered virus

Comparative Immunology, Microbiology and Infectious Diseases
Volume 30, Issues 5–6, September 2007, Pages 309-327

Youjun Feng, George F. Gao.

Abstract

Severe acute respiratory syndrome (SARS) is a newly emerging infectious disease caused by a novel coronavirus (SARS-CoV), which has overwhelmed more than 30 countries claiming nearly 8400 cases with over 800 fatalities. Thanks to the unprecedented international collaboration, the whole-genomes of SARS-CoVs were successfully deciphered shortly after the identification of the causative pathogen for outbreak of SARS in southern China, in 2003. Hitherto, the SARS-CoV, as a viral paradigm of emerging infectious entities, has been extensively studied that has ranged from epidemiology, molecular virology/immunology to structural genomics. Also, several lines of breakthroughs have been record-brokenly obtained, that included the finding of ACE2, a functional receptor for the SARS-CoV, solution of the 3CLpro structure, a first crystal structure of SARS-related macromolecules, revealing of bats as natural reservoirs for SARS-like viruses and the possible involvement of civet cats in the SARS emergence. This review intends to outline the major progress in the journey of SARS-related exploration, by emphasizing those inaugurated studies with milestone-like significance contributed by Chinese research groups.

Keywords

Severe acute respiratory syndrome (SARS), Coronavirus (CoV), SARS-CoV, Molecular epidemiology, Natural reservoir, Receptor, T cell immunity, CTL epitopes, Structural genomics

Isolation and identification of an scFv antibody against nucleocapsid protein of SARS-CoV

Microbes and Infection
Volume 9, Issue 8, July 2007, Pages 1026-1033

Aizhi Zhao, Weijun Qin, Yueheng Han, Weihong Wen, Wenhong Zhang, Zhonghui Lian, Gang Chen, Zhuoli Zhang, Jianqiang Peng, He Wang, Yinglu Guo.

Abstract

To develop reagents for early diagnosis and therapeutic drugs against SARS-associated coronavirus (SARS-CoV), a large (3 × 109) immunized human antibody library was constructed from peripheral blood mononuclear cells from six SARS convalescent patients. A single chain variable fragment antibody (N18) with high affinity against N protein of SARS-CoV was isolated. Sequence analysis revealed that the VL gene was composed of VL3 h (V lambda subgroup) and JL2 regions and the VH gene was composed of VH1-69 (VH1 subgroup), D2-15, D3-22 and JH6 regions. Soluble N18 antibody was expressed in Escherichia coli HB2151, purified by Ni–NTA affinity chromatography and verified by SDS-PAGE and Western blot. The potential application for early diagnosis was evaluated using N protein capture ELISA in which N18 antibody demonstrated high sensitive activity in detecting N protein of SARS-CoV. Finally, the potential usefulness of the N18 antibody in prophylaxis, vaccine design and therapy of SARS is discussed.

Keywords

SARS-CoV, scFv, Nucleocapsid, Phage display

Utility of the aged BALB/c mouse model to demonstrate prevention and control strategies for Severe Acute Respiratory Syndrome coronavirus (SARS-CoV)

Vaccine
Volume 25, Issue 12, 8 March 2007, Pages 2173-2179

Leatrice N. Vogel, Anjeanette Roberts, Christopher D. Paddock, Gillian L. Genrich, Elaine W. Lamirande, Sagar U. Kapadia, John K. Rose, Sherif R. Zaki, Kanta Subbarao.

Abstract

The causative agent of Severe Acute Respiratory Syndrome (SARS) was identified as a coronavirus (CoV) following the outbreak of 2002–2003. There are currently no licensed vaccines or treatments for SARS-CoV infections. Potential prevention and control strategies that show promise in vitro must be evaluated in animal models. The aged BALB/c mouse model for SARS supports a high level of viral replication in association with clinical illness and disease that mimics SARS in the elderly. We tested two preventive strategies, vaccination and passive transfer of serum antibody, to determine the extent of protection achieved against SARS-CoV challenge in this model. These approaches were able to achieve or induce antibody titers sufficient to reduce viral load, protect from weight loss and reduce or eliminate histopathologic changes in the lungs of aged mice. This study validates the utility of the aged BALB/c mouse model for evaluation of the efficacy of vaccines and immunoprophylaxis.

Keywords

SARS-CoV, Aged mouse model, Prophylaxis

Antibodies against trimeric S glycoprotein protect hamsters against SARS-CoV challenge despite their capacity to mediate FcγRII-dependent entry into B cells in vitro

Vaccine
Volume 25, Issue 4, 8 January 2007, Pages 729-740

Yiu Wing Kam, François Kien, Anjeanette Roberts, Yan Chung Cheung, Elaine W. Lamirande, Leatrice Vogel, Shui Ling Chu, Jane Tse, Jeannette Guarner, Sherif R. Zaki, Kanta Subbarao, Malik Peiris, Béatrice Nal, Ralf Altmeyere.

Abstract

Vaccine-induced antibodies can prevent or, in the case of feline infectious peritonitis virus, aggravate infections by coronaviruses. We investigated whether a recombinant native full-length S-protein trimer (triSpike) of severe acute respiratory syndrome coronavirus (SARS-CoV) was able to elicit a neutralizing and protective immune response in animals and analyzed the capacity of anti-S antibodies to mediate antibody-dependent enhancement (ADE) of virus entry in vitro and enhancement of replication in vivo. SARS-CoV-specific serum and mucosal immunoglobulins were readily detected in immunized animals. Serum IgG blocked binding of the S-protein to the ACE2 receptor and neutralized SARS-CoV infection in vitro. Entry into human B cell lines occurred in a FcγRII-dependent and ACE2-independent fashion indicating that ADE of virus entry is a novel cell entry mechanism of SARS-CoV. Vaccinated animals showed no signs of enhanced lung pathology or hepatitis and viral load was undetectable or greatly reduced in lungs following challenge with SARS-CoV. Altogether our results indicate that a recombinant trimeric S protein was able to elicit an efficacious protective immune response in vivo and warrant concern in the safety evaluation of a human vaccine against SARS-CoV.

Keywords

SARS-CoV, Protection, ADE