Chronic Viral Infection and Primary Central Nervous System Malignancy

Primary central nervous system (CNS) tumors cause significant morbidity and mortality in both adults and children. While some of the genetic and molecular mechanisms of neuro-oncogenesis are known, much less is known about possible epigenetic contributions to disease pathophysiology. Over the last several decades, chronic viral infections have been associated with a number of human malignancies. In primary CNS malignancies, two families of viruses, namely polyomavirus and herpesvirus, have been detected with varied frequencies in a number of pediatric and adult histological tumor subtypes. However, establishing a link between chronic viral infection and primary CNS malignancy has been an area of considerable controversy, due in part to variations in detection frequencies and methodologies used among researchers. Since a latent viral neurotropism can be seen with a variety of viruses and a widespread seropositivity exists among the population, it has been difficult to establish an association between viral infection and CNS malignancy based on epidemiology alone. While direct evidence of a role of viruses in neuro-oncogenesis in humans is lacking, a more plausible hypothesis of neuro-oncomodulation has been proposed. The overall goals of this review are to summarize the many human investigations that have studied viral infection in primary CNS tumors, discuss potential neuro-oncomodulatory mechanisms of viral-associated CNS disease and propose future research directions to establish a more firm association between chronic viral infections and primary CNS malignancies

Purification of cell culture-derived influenza virus A/Puerto Rico/8/34 by membrane-based immobilized metal affinity chromatography

The presented study focuses on the feasibility of immobilized metal affinity chromatography for purification of Madin Darby canine kidney cell culture-derived influenza virus particles. Therefore, influenza virus A/Puerto Rico/8/34 was screened for adsorption to different transition metal ions attached to iminodiacetic acid. Subsequently, capturing of the same virus strain using zinc-modified iminodiacetic acid membrane adsorbers was characterized regarding viral recoveries, host cell nucleic acid and total protein depletion as well as zinc ion leaching. In addition, the effect of the imidazole proton pump on virus stability was studied based on the hemagglutination activity. During adsorption in the presence of 1 M sodium chloride the majority of virus particles were recovered in the product (64 % Hemagglutination activity). Host cell nucleic acid and total protein content were reduced to approximately 7 % and 26%, respectively. This inexpensive and rapid method was applied reproducibly for influenza virus A/Puerto Rico/8/34 preparations on the laboratory scale. However, preliminary results with other virus strains indicated clearly a strong strain dependency for viral adsorption. Copyright © 2009 Elsevier B.V. All rights reserved. [Accessed September 16, 2009

Affinity capture of cell culture-derived influenza virus particles

Human influenza vaccines are traditionally produced in embryonated chicken eggs. However, due to several disadvantages of this method, mammalian cell culture based influenza vaccine production processes are currently being established demanding new virus purification methods. Our study provides comprehensive results from three different strategies to capture Madin-Darby canine kidney (MDCK) cell culture-derived influenza virus particles (A/Wisconsin/67/2005, A/Puerto Rico/8/34, B/Malaysia/2506/2004) based on affinity and pseudo-affinity adsorption. First, an affinity based capture step, lectin-affinity chromatography (LAC), was developed. This method was investigated concerning the selection of lectins and matrices, viral recoveries and contaminant depletion as well as process robustness. LAC showed a high degree of contaminant reduction, in particular host cell dsDNA depletion. The results from LAC represent a high potential of an affinity capture step at the beginning of a downstream process for production of viral vaccines. Influenza viruses have an affinity to sulfated carbohydrates, such as heparin or sulfated cellulose. Hence, column based Cellufine® sulfate is often used in industrial influenza virus purification. The main disadvantage of this method is the limited flow rate, due to high back pressure, leading to suboptimal process productivity. To overcome this drawback, we have developed a second capturing method for influenza viruses based on sulfated reinforced cellulose membranes (SCM). Compared to commercially available cation exchange membrane adsorbers and column based Cellufine® sulfate resin, these membrane adsorbers achieved high product recoveries and contaminant reduction. In addition, the SCM allow an increased flow rate during capturing leading to superior productivity compared to conventional bead chromatography. Hence, this method is an economic alternative for industrial influenza vaccine production. The third purification strategy was capturing of influenza viruses by immobilized metal affinity chromatography (IMAC) using zinc modified membrane adsorbers. This method shows valuable purification results for the influenza virus strain A/Puerto Rico/8/34. However, IMAC depends highly on the primary structure of viral envelope proteins as well as the accessibility of certain amino acids. Hence, IMAC is an interesting capturing method of A/Puerto Rico/8/34 in a laboratory scale, but is only of limited interest for industrial vaccine production processes