Experiment 4: Transfection of hemophilia B dogs
In this next study the investigators transduced hemophilia B dogs with rAAV-MFG-cFIX. Their purpose was to demonstrate corrected bleeding times in a larger animal model.
How was this accomplished?
They used 2 hemophilia B dogs, and prior to intra-portal infusion, the dogs were infused with normal dog plasma. The reason for the plasma infusion is similar to the mice, to expand their blood volume as a preventative health measure against any excessive bleeding during the study. One normal donor dog tested positive for anti-AAV so this dog was eliminated from the study. The two remaining dogs were then transduced with 2 x10 to the12th particles of rAAV-MFG-cFIX. This dose was approximately 10% of the dose per body weight of the dose used on the mice. Tests run on the dogs in this study include WBCT, % inhibition, aPTT, and cFIX assays. The investigators also ran blood chemistries on the dogs to monitor their liver function. All the dogs included in this study were tested for anti-AAV neutralizing antibodies prior to surgery.
What is the reason they would test for anti-AAV neutralizing antibodies in the dogs?
The presence on antibodies to the vector used in this study would be a complication because they want to avoid any kind of immune response to the vector.
What are the advantages and disadvantages with working with canines in this study?
Canines represent a larger model more closely paralleling a human subject in looking at the effects of the transfection and figuring the effective dosage levels. A disadvantage is that one is limited in the number of canines that can be used as test subjects. Larger numbers would give more accurate data.
To view the results of this experiment,
click
here
