TC-83-derived alphavirus vectors, particles and methods

Abstract

The present disclosure provides TC-83 VEE-derived replicons, alphaviral replicon particles and immunogenic compositions containing TC-83 alphaviral replicon particles which direct the expression of at least one antigen when introduced into a suitable host cell. The TC-83 VEE-derived ARPs described herein are improved in that they are subject to a lower vector-specific immune response than prior art ARPs.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims benefit of U.S. Provisional Application No. 60 / 572,212, filed May 18, 2004, which application is incorporated by reference herein to the extent there is no inconsistency with the present disclosure.ACKNOWLEDGMENT OF FEDERAL RESEARCH SUPPORT [0002] This invention was made, at least in part, through funding from the United States government, through grants from the National Institutes of Health, grant numbers 1U01 AI056438-01 and 5U01 AI 55071-02.BACKGROUND OF THE INVENTION [0003] The present invention relates to recombinant DNA technology, and in particular to introducing foreign nucleic acid in a eukaryotic cell, and more particularly to compositions and methods for producing alphavirus replicon particles useful in immunotherapies and / or gene therapy applications. In particular, the present invention discloses a genetic background for the alphavirus replicon particle system that is based on the Venezuelan Equine ...

AI Technical Summary

Benefits of technology

[0009] The present invention provides compositions of infective, replication-defective, highly immunogenic alphavirus replicon particles based on a particular alphavirus strain, i.e., the TC-83 of VEE, and methods of preparation thereof. As described previously (see, for example, U.S. Pat. Nos. 5,792,462; 6,156,558; 5,811,407; 6,008,035; 6,583,121; WO 03 / 023026; U.S. Publication No. 2003 / 0119182, all incorporated herein by reference), functional alphavirus replicon particles have been made from several different alphaviruses and chimeras thereof (see, for example, U.S. Publication No 2003 / 0148262). These particles are useful in vaccine and gene therapy applications, and the optimal characteristics of the alphavirus replicon particles differ in these applications. For instance, it may be useful to reduce the expression of proteins from the replicon during gene therapy applications, and thus techniques have been developed in the art to reduce such expression (see e.g. U.S. Pat. Nos. 5,843,723 and 6,451,592). In the case of vaccine applications, maximizing the expression of the heterologous RNA from the replicon, minimizing any anti-vector responses, and targeting the tissues and cells of the immune system are desirable features. The alphaviruses Venezuelan Equine Encephalitis (VEE) virus and South African Arbovirus No. 86 have proved particularly useful in the vaccine applications. To improve the safety of these alphavirus vectors in the rare event that a replication-competent virus is generated, at least one attenuating mutation has been introduced into the alphaviral genomic fragments. The present inventors have now discovered that the TC-83 strain of VEE can be used as the genetic background for an alphavirus replicon particle system which provides a surprisingly effective VEE particle preparation for use in immunogenic compositions and which has other surprisingly advantageous properties useful in a vaccine vector system, including the ability to prepare purified preparations with ease.

[0011] The inventors have now produced a replicon particle vaccine based on the TC-83 strain, and it has several surprisingly advantageous characteristics for both vaccine and gene therapy applications including, but not limited to, much higher yields as compared to those achieved with particles based on wild-type VEE or on those carrying other attenuating mutations; lowered anti-vector responses; increased purity; excellent immunogenicity that is comparable to other VEE strains carrying only one, two or three attenuating mutations, and no non-responsiveness, in contrast to the noted non-responsiveness of animals to the live TC-83 strain used as a vaccine.

[0012] Additionally, the inventors have discovered that packaging an alphavirus replicon in the VEETC83 structural proteins results in significantly higher yields of replicon particle vaccines from cell cultures. Thus, the VEETC83 structural proteins can be advantageously used to package replicons from other alphaviruses, including other strains of VEE.

Problems solved by technology

However, the methods used do not exclude contributions from other mutations, and the existence of the numerous other nonconservative mutations in the TC-83 genome make it impossible to predict whether it can serve as an effective genetic background for the replicon particle system.

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