Yep, looks like a translation error from the tax/fee codes. The correct naming should be :
United Kingdom Passenger Service Charge (UB) $69.50
AA YR surcharge (YR) $496.00
US International Departure Tax (US) $16.70
US September 11th Security Fee (AY) $2.50
US Passenger Facility Charge (XF) $4.50
USDA APHIS Fee (XA) $5.00
US Immigration Fee (XY) $7.00
US Customs Fee (YC) $5.50
US International Arrival Tax (US) $16.70
Czech Embarkation Tax (CZ) $25.50
(I'm assuming your routing is BOS-LHR-PRG return in Y or Y+ with no stopover in LON ?)
And yes, BA do apply the fuel surcharge on AA now. The only way to reduce this transatlantic is to fly on EI via DUB.
Have you purchased the ticket yet ?
hth