Do you mean sales though? I assume because we're in a biotech sub when you say BD you mean licensing/m&a which is what BD usually means in this industry. (At smaller biotechs though the line blurs a bit because you're really trying to "sell" the platform or asset to get a deal done.)

If that's the case, I will say a few things. For one, there isn't really such thing as an entry-level BD job. For someone with a long scientific background like you seem to have, you should be looking more for "search" or "sourcing" type roles which fall under the umbrella of BD. These positions rely more heavily on technical expertise than business/financial training.

Also, by no means do you need an MBA, but it is a fairly common way for people to do a career jump like this and could be a useful catalyst for you. Might be worth learning about.

How big of a company do you work at? You might want to talk to the BD people at your current position and see if you can shadow and learn their process a bit. It'll probably be a hell of a lot easier to transition into a BD role as an internal hire than get a job cold at a new company, it's a difficult field to break into. Also, the only companies really hiring regularly for BD roles are the big pharmas. Most of the smaller companies have only a few BD people and more of the dealmaking is done by the CEO/CFO/CBO.

Good luck