What processes do eukaryotic and prokaryotic cells use to kill viruses?

I should know this myself, but I was answering a question last week, and this question popped into my head.

Are there any methods used by either cells to kill viruses before they actually enter the cell genome?

I seem to recall eukaryotic cells have the ability to phagositize viruses, but I can't recall for sure.

I did a google search, but maybe I'm not using the best search terms.

Answers, comments, rude noises, all are welcome!

What processes do eukaryotic and prokaryotic cells use to kill viruses?free anti virus

There are a number of ways to kill some viruses in eukaryotic cells but usually there are other smarter viruses not affected in the same mechanism. I will only give a couple of interesting examples. The first is based on the cellular RNA interference (RNAi) mechanism. Double strand RNA viruses are processed by an RNase III enzyme into ~20 base pair (bp) long short RNA. These can bind to mRNA of the virus and lead to their degradation via the RNAi process with Ago2 and the so called RNA induced silencing complex (RISC) mediated pathway. Some viruses are smart enough to produce a small inhibitor molecule that binds the 20 bp small RNA and thus inhibit the RNAi process.

There are other processes that target long double stranded RNA - most like from viruses because the cell does not make this type of RNA duplexes. The recognition of the long dsRNA activate the interferon pathway and lead to apoptosis of the cell and hopefully killing the viruses with it. However, again there are viruses that produce molecules that inhibit apoptosis and thus will survive long enough to replicate themselves before the cells eventually die.