Jeremy N. Stables

Characterization of factors involved in human papillomavirus type 16-mediated immortalization of oral keratinocytes

We have examined intrinsic and external factors that influence human papillomavirus type 16 (HPV-16)-mediated immortalization of oral keratinocytes. The efficiency with which HPV can immortalize human oral keratinocytes was quantified and a considerable difference in the transfection and immortalization competence of the cells was detected. The ability of HPV-16 to immortalize oral cells appeared to be linked to the age of the culture upon transfection. The addition of dexamethasone to the transfected cultures increased the efficiency of immortalization, possibly indicating a role for a critical level of HPV gene expression in initial outgrowth of immortalized colonies. We also document in detail the changes in the oral keratinocyte induced by HPV-16 immortalization. These include alterations associated with crisis and feeder independence as well as basic changes in keratin expression and differentiation.

Development and characterization of a novel xenograft model permissive for human papillomavirus DNA amplification and late gene expression.

Human papillomaviruses (HPVs) are important human pathogens associated with a range of epithelial neoplasia. The rising incidence of HPV infection and association of HPV with malignancy has led to increased interest in appropriate management of these infections. Development of new therapies for viral warts has been frustrated by the lack of availability of models permissive for viral replication. Here we describe the development of HPV-severe combined immunodeficient mouse model which reproduces mature HPV-infected epithelia. Grafting of anogenital and laryngeal papillomas harbouring either HPV-6 or HPV-11 resulted in the formation of a differentiated neo-epithelium exhibiting the hallmark features of HPV infection including basal hyperplasia, acanthosis and koilocytosis. The reformed warty epithelium contained amplified HPV DNA and expressed capsid protein in the differentiated layers. A striking feature is the production of macroscopic papillomata in an anatomically relevant and accessible site, providing a system of particular relevance for the temporal evaluation of developing lesions and selection of antiviral agents.

The effect of two novel analogues of antimycin A on oxygen consumption and survival of filarial nematodes in vitro

The effects of two novel analogues of antimycin A (BWA466C and BWA728C) on filarial oxygen consumption, energy generation and survival were investigated in vitro. For comparison, incubations were performed with a range of mitochondrial respiration inhibitors. All compounds tested (rotenone, antimycin A, KCN, oligomycin, CCCP, rafoxanide, BWA466C and BWA728C) inhibited oxygen uptake. The two analogues were less potent than antimycin A at impairing respiration of either filariae or beef heart submitochondrial particles. However, the two compounds affected motility and were lethal in vitro. Although the analogues affected oxygen uptake similarly to antimycin A itself, the levels of ATP were significantly lower than those noted in the presence of antimycin A. Glucose consumption and lactate output were markedly reduced by BWA466C and BWA728C. Glucose transport (measured as 2-deoxy-[2,6-3H]glucose) was reduced after treatment with BWA728C. It is likely that a combination of the effects on glucose transport and inhibition of oxidative pathways of carbohydrate metabolism may lead to worm death in vitro.