1-4 is just the numbered versions. Again, this is like the end of the series (as far as we know) so, there is MG1+2, then the 4 MGS, then the Handheld Peacewalker and Portable Ops....
Basically, there is gonna be a whole crap load of story events you might not understand with this game if you don't play the others. They are not required to have fun (MGS is the GTA of hide n seek games, I spent hours on Ground Zero messing around without doing anything related to the mission).
But story wise, playing the others will boost your enjoyment as you'll get events that have been missing in the whole story arc - how Big Boss goes rogue, and what Kid Snake is up to.
TL;DR:
Perhaps no, you can probably read a quick plot summary of MGS3, Portable Ops and Peacewalker which were released on PSP. This game is suppose to be chronological after those two and set before Metal Gear 1+2, which are both set before Metal Gear Solid 1+2+4.
You won't need the background info to enjoy the game, but you'll probably have a lot of questions in regards to the plot.