Protecting all civilized systems from nanoswarms, software viruses, epidemics and blights are advanced nanotechnological, software, ecological and memetic immune systems. Without them civilisation would collapse from the spontaneous emergence of replicators, not to mention deliberate (mis)use of them. Designing and maintaining the extensive immune systems is a profession that encompasses many individuals; in some regions like the Vela Immunity they are the largest work segment (17% of all employed entities, according to 10,000 Vela statistics).
Immune design is a broad field with thousands of specialties. At the core the problem is the same: identifying and neutralizing unwanted replicators. The general methods of applied immunology is then specialized for different applications such as nanoimmune and software systems. Since the number of components of advanced immune systems is vast, there are entire disciplines devoted to just microscopic parts like nanograppler design, software seismology and memetic weak eigenspace prediction.
Although planetary immune systems and most software protections have to be designed by super-intelligent entities, there is plenty of work among the baselines as immune designers too. The reason is that all advanced immune systems are complex adaptive systems, and quite often misbehave in unexpected or irritating ways. Fixing all these quirks - without compromising security - is part of the immune designer job. There are also many low-level immune systems that deal not with the serious threats but simply maintaining a comfortable environment by limiting the spread of pests - be they madverts, memeoids or spy nanoware.
Perhaps the most famous nanoimmune designer of all time was Hermann Laustrom-Xiang 452-541 AT (2421-2510 c.e.), who designed many of the protocols that were eventually included in GAIA. Although his name was reviled for a long period after the Great Expulsion, today he is viewed as one of the great geniuses of terragenkind. The fact that he was "merely" a cyborged superior and not an AI adds to his mystique.
Nanosome - Text by Anders Sandberg, in Transhuman Terminology Generic term for any nanodevices (whether hylo or bio) existing symbiotically inside biological cells, doing mechanosynthesis and disassembly for it and replicating with the cell.