Development of biotechnological tools for studying infectious pathways of canine and human parvoviruses

Abstract

Leona Gilbertin väitöskirjatyö antaa uutta tietoa parvovirusten pinnanmuokkauksesta ja hyödyllisyydestä virologian, geeniterapian ja biolääketieteen sovelluksissa. Parvovirukset ovat pieniä, yksisäikeistä DNA:ta sisältäviä eläinviruksia, jotka kykenevät infektoimaan isäntänsä soluja. Ihmisillä ne aiheuttavat ihottumaa sekä nivelkipuja. Tutkimuksessa tuotettiin bakuloviruksen avulla hyönteissoluissa sekä koiran että ihmisen parvoviruksen rakenneproteiineista fluoresloivia fuusioproteiineja. Selvisi, että parvoviruksen pinta sopii hyvin muokkaamiseen ja vieraiden molekyylien ilmentämiseen. Lisäksi havaittiin, että bakuloviruksia voidaan käyttää geeninsiirtovälineenä mm. parvovirusproteiinien liikkeiden tarkkailemiseen nisäkässoluissa.

Parvoviruses are among the smallest vertebrate DNA viruses known to date. The production of parvovirus-like particles (parvo-VLPs) has been successfully exploited for parvovirus vaccine development. The baculovirus expression vector system (BEVS) has been the popular choice to correctly express and produce VLPs. These multimeric structures are morphologically and structurally identical to the original virus. The capsid proteins can also be produced individually or in combination to monitor structural protein functions in the parvovirus life cycle. Moreover, the ability of baculoviruses to transduce a wide range of mammalian cells has brought about the opportunity to use these viruses as gene vectors to express individual parvoviral structural proteins of interest. The present study was aimed to address a set of problems in the field of parvovirus biology and biotechnology with the development of novel parvoviral biotechnological tools. Non-fluorescent and fluorescent fusion proteins of the structural proteins of canine and human parvovirus, as well as recombinant baculoviruses encoding these proteins were successfully generated. Enhanced green fluorescent protein was incorporated on the surface of the parvo-VLPs and these recombinant baculoviruses (rBVs) were shown to be practical when following parvoviral structural proteins in vivo. The chimeric parvo-VLPs were further scrutinized specifically with regard to their assembly capabilities, trafficking events and nuclear targeting. In addition, a baculovirus-mediated de novo vector system was created to shed additional light on the synthesis and trafficking of individual parvoviral structural proteins in mammalian cells. Together, these results showed that the surface of parvoviruses could be modified, display a large foreign moiety and assemble correctly. Similarly recombinant baculoviruses could be used as gene transfer vectors to monitor the individual parvoviral proteins in transduced mammalian target cells. The parvovirus display and transduction techniques show promise as potential tools for various scientific applications ranging from basic virological studies, to gene therapy applications, and developments in biomedicine.