never start antivirals like tenofovir or entecavir they will be useful only when liver damage gets adavnaced or after 35-40yo, only immune modulators like interferon are ok
if infected at birth he should have a normal life, just monitor liver damage by fibroscan and hbsag quantity, if hbsag has got lower by interferon keep therapy for 1-2years and then discontinue and follow hbsag
interferon can be made several times if hbsag gets lower and eradicaed by second or third try
There is a special support list for parents of children with Hepatitis B. It is a special group within the Hepatitis B information and Support list (http://hblist.org/)
http://health.groups.yahoo.com/group/hbv-adoption/join
Good luck!