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  • Simian Immunodeficiency Virus Vector

Simian Immunodeficiency Virus Vector (SIV vector)

A vector derived from Simian Immunodeficiency Virus (SIV). This vector is similar to Human Immunodeficiency Virus (HIV, AIDS virus)-based vectors in many aspects, which are now entering clinical trials in the US. Both SIV and HIV are members of lentivirus family, whose characteristics include capabilities to introduce genes efficiently into not only actively dividing cells but also terminally differentiated cells such as neurons, and to maintain gene expression for a long period of time. ID Pharma ’s SIV vector shares the same effectiveness as other lentivirus vectors, but also has extra advantages in safety over HIV vectors:

  1. Unlike HIV and other lentivirus vectors, ID Pharma ’s SIV vector is based on SIVagm, a SIV strain isolated from African Green Monkey, which has no pathogenicity (immunodeficiency) in its natural host.
  2. The nucleotide sequence of ID Pharma ’s SIV vector has very low homology to that of HIV. Therefore, the possibility of homologous recombination occurring between ID Pharma ’s SIV vector and HIV is remote even when these two coexist in a patient’s cell. Thus, the risk of generating replication competent recombinant virus is considered extremely low. This feature gives this vector additional safety.

ID Pharma has succeeded in creating the third generation of SIV vector, which satisfies the safety standard of the world.

When introduced subretinally, ID Pharma ’s SIV vector stably maintained the therapeutic gene expression over two years without causing any damage to the site of administration. Encouraged by this observation, preclinical studies using this vector for the treatment of Retinitis Pigmentosa and Glaucoma are underway.

F/HN-Pseudotype SIV Vector

ID Pharma developed the World’s first lentivirus vector intended to be used in the respiratory system with practical efficiency. This vector incorporates the envelope proteins (F/HN) of Sendai virus on its envelope. In mice, it is capable of stably expressing a therapeutic gene for over one year in nostril epithelium when introduced intranasally, suggesting that the vector could introduce genes into epithelial stem cells. Therefore, this vector is expected to be suitable for the treatment of hereditary respiratory disorders.

This vector is a culmination of the knowledge and technologies that ID Pharma accumulated during the development of Sendai virus vector. Sendai virus infects airway cells very efficiently by a mechanism involving two proteins on its envelope, F and HN. We undertook the challenge of creating an SIV vector that expresses these two SeV proteins on its envelope (F/HN-pseudotyped SIV vector), and succeeded with much effort and ingenuity. As intended, this new vector was able to transfer genes to mouse airway cells efficiently. The Cystic Fibrosis Gene Therapy Consortium, an authoritative organization in the United Kingdom, gave a high value to this technology, and provided financial support for joint development of a gene therapeutic medicine for the treatment of Cystic Fibrosis, a disease that remains without fundamental cure. This joint development project is currently underway. In addition, the usefulness of this vector in the treatment of Retinitis Pigmentosa has been proven in a collaborative research with Kyushu University. As an added feature, this vector improves the speed of gene transfer, which is relatively slow when the SIV vector is pseudotyped with the conventional VSVG protein, and introduces genes to target cells very quickly.