Not true. Mosquitoes could feast on recently-killed animals and still breed and have offspring. There are "artificial dogs" used to raise mosquitoes in a lab environment. Although some of the blood of the artifical dogs comes from real dogs, in principle it doesn't have to. In no way does a mosquito depend on the cellular metabolism and nuclear synthesis of the host in order to propagate. But a virus will only replicate if that machinery is functioning in a living cell, and the virus is able to subvert those processes to its own end.
Except for yogurt and raw veggies, I don't eat anything that is actually alive, and a diet of 100 % cooked stuff is 100% dead, nevertheless it is possible to live on such a diet, and my ability to reproduce doesn't depend on the life of any specific organism, but rather overall nutrition. It is possible to synthesize proteins, lipids, vitamins, and so forth from mineral sources, and I suspect a nutritionally complete diet could be lab-synthesized soon if not already. The fact we eat things that used to be alive is just an artifact of our multi-billion year ancestry, but unlike viruses, we don't absolutely depend on it for our propagation. We use the stuff we eat as building blocks for our own molecules; viruses hijack the machinery of whatever host they have taken hostage, and trick it into making more of themselves. They don't "eat" the other cells, they don't make anything themselves, certainly not copies of themselves (reproduction) nor do they metabolize nor respire. Those essential functions are all done by the infected host. If there's no host, there's no propagation.
Where did I say that we eat things that are still alive? Where did I even imply it?
There are things that feed directly on minerals, but animals eat living things or things or recently living things or things produced by living things. That is a form of parasitism.
You left out "intentionally."