timid nonplayful 7week pup

Question
We are adopting a puppy from the spca.  He is just over 7 weeks and will be coming home at the end of the week.  The mom is a Siberian Husky cross and no ideas about the dad.  Mom had a litter of 4 at the shelter and puppies have been raised in the kennel all their life.  He is the largest puppy yet is picked on by the other puppies and he does not defend himself, instead just yelps and walks away.  We visit daily yet he will not come and greet us as the other three pups do.  He doesn't play with any of the toys and won't eat treats from our hand.  When we or any of the staff hold him he will go limp and shiver for about 5-10 minutes and then just stay limp.  All the other puppies will go outside and play yet he will just lie at the kennel threshold and watch...seemingly not wanting to go out into the snow.  Now for the questions.  How do we get him to be interested in play (with both us and other dogs), to not be afraid of us, people and his new home?  The staff at the shelter have been  keeping an eye on him, worried about failure to thrive, but he is keeping his weight and is otherwise healthy (all pups had been dewormed twice when much younger).

Answer
Well he may open up once he is out of the shelter-as that can be very stressful for a puppy,esp if that is all they have known

Some dogs never really play with toys,it's just there personality-but what you can try is to use something called a kong toy and put peanut butter inside of it

Some dogs,like some people will always be a bit shy-I have a nine year old dog that almost never lets strangers pet her,but sometimes she will come up to some people,that the best approach for a shy dog,tell people to put there hand out but let the dog come to them