Comparative Evaluation of Human Papillomavirus Type 16 L1 Protein Expressed in Plasmid- and Baculovirus-Based Systems in Insect Cells.

Human papillomavirus (HPV) has been associated with specific types of papillomas, lesions at particular anatomic sites, and malignancies. The HPV16 and HPV18 have been shown to play a role in a variety of carcinomas. The most documented HPV-associated cancer is cervical carcinoma. Suitable antigens are needed to be identified for the diagnostic tests and vaccines and the expression of L1 recombinant protein should be accelerated in papillomaviruses. Therefore, in this study, the expression of the L1 protein of HPV16 was evaluated and compared in insect cells using a plasmid and a baculovirus system. The expression of the L1 protein of HPV16 in insect cells was investigated using a plasmid (InsectDirect) and a baculovirus system (BacMagic). The expressed recombinant proteins were purified from the Sf9 lysate using Ni-NTA resin columns. The characterization of recombinant L1 protein expressed in both systems (BacMagic and InsectDirect) was performed using immunofluorescence, SDS-PAGE, western blot, and dot blot. The yields of the purified proteins from the plasmid- and baculovirus-based systems (10 ml culture; 107 cells) had the ranges of 455-495 µg/ml and 1.44-1.6 mg/ml as analyzed by spectrophotometer, respectively. The SDS-PAGE analysis of purified proteins revealed that the recombinant proteins with the expected size of 58 KDa were produced in both InsectDirect and baculovirus systems. A high degree (95%) of purification was achieved using this system as observed in SDS-PAGE. The purified L1 protein in the baculovirus system was clearly more efficient than the InsectDirect system. The results of this study indicate that the BacMagic system is an appropriate tool for large scale protein production and provides an alternative to the traditional baculovirus system. In addition, the InsectDirect system might provide a rapid and dependable pointer of whether a protein can be successfully produced in a baculovirus system. Both InsectDirect and BacMagic systems present remarkable savings in cost and time.

Age-related pattern of KI and WU polyomavirus infection.

BACKGROUND: The role of two recently identified polyomaviruses, KI and WU, in the causation of respiratory disease has not been established. OBJECTIVES: To determine the prevalence of KI and WU viruses (KIV and WUV) in 371 respiratory samples and evaluate their contribution to respiratory disease. STUDY DESIGN: Specimens were screened for KIV and WUV using single, multiplex or real time PCR; co-infection with other respiratory viruses was evaluated. RESULTS: Of the 371 samples analysed, 10 (2.70%) were positive for KIV and 4 (1.08%) were positive for WUV yielding an overall case prevalence of KIV and WUV infection of 3.77%. KIV and WUV were identified in patients aged<15 years (11 patients) with upper or lower respiratory tract infection and >45 years (3 patients) with upper respiratory tract infection. Co-infections were found in 5 (50%) and 3 (75%) of the KIV and WUV positive samples, respectively. CONCLUSIONS: This study supports previous conclusions that KIV and WUV detection in the respiratory tract may be coincidental and reflect reactivation of latent or persistent infection with these viruses. The age distribution of KIV and WUV infection in this study mirrors that found for the other human polyomaviruses, BK and JC.