Browsing by Author "Khan, Sehaam"

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    The genetic organisation of a 2,966 basepair DNA fragment of a Single Capsid Nucleopolyhedrovirus isolated from Trichoplusia ni
    (Springer Verlag, 2002) Fielding, Burtram C.; Khan, Sehaam; Wang, Weizhou; Kruger, Courtney; Abrahams, Rayaana; Davison, Sean
    In order to investiagte the genomic organization of the Trichoplusia ni Single Capsid Nucleoplyhedrovirus (TnSNPV) , a 2,966 base pairs (bp) genomic fragment was sequenced. The fragment was found to contain five open reading frames (ORF's) homologous to baculovirus genes, including p26, fibrillin (p10), AcMNPV ORF-29, late expression facor 6 (lef 6) and the C-terminal portion of p74, on either stand of DNA. Predicted amini acid sequences for the ORFs were compared and identity values of between 12% and 54% were observed. Clustering and arrangement of the TnSNPV genes were similar to the clustering reported for SeMNPV, confirming TnSNPV was a Group II NPV.
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    Over-expression of severe acute respiratory syndrome coronavirus 3b protein induces both apoptosis and necrosis in Vero E6 cells
    (Elsevier, 2006) Khan, Sehaam; Fielding, Burtram C.; Tan, Timothy H.P.; Chou, Chih-Fong; Shou, Shen; Lim, Seng Gee; Hong, Wanjin; Tan, Yee-Joo
    The genome of the severe acute respiratory syndrome coronavirus encodes for eight accessory viral proteins with no known homologues in other coronaviruses. One of these is the 3b protein, which is encoded by the second open reading frame in subgenomic RNA 3 and contains 154 amino acids. Here, a detailed time-course study was performed to compare the apoptosis and necrosis profiles induced by full-length 3b, a 3b mutant that was deleted by 30 amino acids from the C terminus (3b 124-154) and the classical apoptosis inducer, Bax. Our results showed that Vero E6 cells transfected with a construct for expressing 3b underwent necrosis as early as 6 h after transfection and underwent simultaneous necrosis and apoptosis at later time-points. At all the time-points analysed, the apoptosis induced by the expression of 3b was less than the level induced by Bax but the level of necrosis was comparable. The 3b 124-154 mutant behaves in a similar manner indicating that the localization of the 3b protein does not seems to be important for the cell-death pathways since full-length 3b is localized predominantly to the nucleolus, while the mutant is found to be concentrated in the peri-nuclear regions. To our knowledge, this is the first report of the induction of necrosis by a SARS-CoV protein.
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    Severe acute respiratory syndrome coronavirus protein 7a interacts with hSGT
    (Elsevier, 2006) Fielding, Burtram C.; Gunalan, Vithiagaran; Tan, Timothy H.P.; Chou, Chih-Fong; Shen, Shuo; Khan, Sehaam; Lim, Seng Gee; Hong, Wanjin; Tan, Yee-Joo
    Severe acute respiratory syndrome coronavirus (SARS-CoV) 7a is an accessory protein with no known homologues. In this study, we report the interaction of a SARS-CoV 7a and small glutamine-rich tetratricopeptide repeat-containing protein (SGT). SARS-CoV 7a and human SGT interaction was identified using a two-hybrid system screen and confirmed with interaction screens in cell culture and cellular co-localization studies. The SGT domain of interaction was mapped by deletion mutant analysis and results indicated that tetratricopeptide repeat 2 (aa 125-158) was essential for interaction. We also showed that 7a interacted with SARS-CoV structural proteins M (membrane) and E (envelope), which have been shown to be essential for virus-like particle formation. Taken together, our results coupled with data from studies of the interaction between SGT and HIV-1 vpu indicated that SGT could be involved in the life-cycle, possibly assembly of SARS-CoV.