Molecular Advances in Severe Acute Respiratory Syndrome-associated Coronavirus (SARS-CoV)

Chow, Ken Yan Ching; Hon, Chung Chau; Hui, Raymond Kin Hi; Wong, Raymond Tsz Yeung; Yip, Chi Wai; Zeng, Fanya; Leung, Frederick Chi Ching

Current knowledge on coronavirus immunity has mainly been acquired from research on animal coronaviruses. Clinical observations have shown that humoral and cell-mediated immune responses may be both necessary against SARS-CoV infection (105 ) . It was reported that T cell (CD3+, CD4 and CD8+) depletion was observed in early infection, but that levels returned to normal as the disease was improved (106 ) . IgG antibody could be detected at the 7th day after the onset of symptoms and kept at high titer at least three months (107 ) . Another report indicated that the virus was still detectable in respiratory and stool specimens by RT-PCR diagnosis but could not be cultured more than 40 days after presentation (108 ) , implying that the antibody could be stimulated rapidly and might restrict the virus infection. However it has also been reported in fowl and feline coronaviral diseases that low-level antibody may exacerbate diseases (109 ) . It is therefore important to conduct further investigations into the immune response to SARS patients in the future so as to benefit the vaccine development and disease control.