रित्रभाइरासफोरा बिसोर भाइरासनि गोदान फोलेराव गोख्रैयै बास्लायनो (सोलायनो) हायो हिसाबै सोलिनो जुजिगासिनो दं।
Retroviruses are challenging to treat as they can rapidly alter (mutate) into new strains of virus.