抗病毒胜肽抑制貓冠狀病毒複製之評估

Abstract

貓傳染性腹膜炎 (Feline infectious peritonitis, FIP) 為貓冠狀病毒 (Feline coronavirus, FCoV) 所引起之一免疫媒介高度致死性疾病，目前尚無有效之疫苗及治療方法。本研究利用以severe acute respiratory syndrome coronavirus (SARS-CoV) 及FCoV之棘蛋白(spike protein, S) heptad repeat 2 (HR2) 序列為基礎所合成之胜肽，藉由抑制FCoV感染之融合效應，測試其抑制病毒複製之效力。結果顯示在20 μM濃度下，SARS-CoV HR胜肽具33% 至55% 之抑制病毒效力，而FCoV-HR 胜肽之抑制病毒效力則可達到72% 至97%。此結果表示相較於SARS-CoV HR 胜肽，FCoV HR 胜肽對於FCoV之抑制更具特異性。進一步探討HR 胜肽與其他已知具抗FCoV複製藥物之加乘作用 (Synergistic antiviral effect)，將SARS-CoV HR胜肽與nelfinavir、Galanthus nivalis agglutinin (GNA) 合併未出現加乘作用，而與人源Interferon-α (IFN-α) 合併，則發現以20 μM FCoV HR胜肽與不同濃度之IFN-α合併後皆出現加乘抗病毒效應。探討此FCoV HR胜肽之抑制機制發現其主要是藉由干擾病毒與標的細胞之融合，進而抑制病毒之複製。總結本實驗之結果，FCoV HR 胜肽為一具有潛力可應用於FIP臨床預防及治療之藥物。

Feline infectious peritonitis (FIP) is an immune-mediated disease with high mortality rate in felids caused by feline coronavirus (FCoV). At present, no effective vaccine or treatments are available for FIP. We carried out fusion inhibition assay to analyze the designed peptides based on spike protein (S) heptad repeat 2 (HR2) sequences of severe acute respiratory syndrome coronavirus (SARS-CoV) and FCoV. The results showed the inhibition percentages of FCoV replication for 20 μM of SARS-CoV and FCoV peptides were 31% to 55% and 72% to 97%, respectively. This indicates that the peptides derived from FCoV are more specific than from SARS-CoV. The effective FCoV-derived peptides were further tested for their synergistic antiviral effect with other known anti-FCoV agents, i.e. Galanthus nivalis agglutinin 會, nelfinavir and human interferon-α (IFN-α). When 20 μM of FCoV HR peptide was combined with different concentrations of IFN-α, a significant synergistic anti-FCoV effect can be observed, however not with GNA and nelfinavir. Investigation of the inhibition mechanism for FCoV-derived HR peptide revealed that the peptide interferes with virus-cell fusion thus leading to a reduction in viral replication. Taken together, the peptides derived from FCoV have the potential to be used as a therapeutic agent in the prevention and treatment of FIP.