You created an account, you got all ready to mine, and Chrome blocked your download.  It said it was a trojan.  You wonder "How can Minergate be giving me a virus?"  The reality is, there are mining programs that are trojan'ed, that someone has slipped in malware that mines for them, or that encrypts your drive, etc...  If you are smart about where you get your mining software, only from official repositories, you will not have any malware/virus/trojan on your PC.  You will need to disable Chrome's safe browsing component to download it, and you will have to disable your Anti-Virus on your machine also, because it too will declare your mining software as malware.  There will be other articles, short how-to's on chrome and AV disabling and exceptions (So your AV doesn't delete your miner once you got it installed and working, during it's nightly scan).

So why is my miner seen by everyone as malware you might ask.  It is simply economics, and the story to explain it is right here:

Imagine you own a business, and it makes 10 million dollars a year.  You have 5000 employees, and each one has their own PC, so 5000 PCs.  You also own 100 servers.  Your electricity bill is 4000 dollars a month.  Your employees use their PCs from 9-5 and about 30% CPU utilization in that 8 hours.  Now imagine someone installs miners on ALL of your PCs and servers.  They are clever and only have the miners mine from 7pm to 7am.  For 2 months, someone has 5100 miners mining for them.  You get an electricity bill for last month that is now 15,000 dollars.  You ask "What the heck?" and then have to pay some network security specialists to find the miners, and remove them.  You just spent 30,000 dollars on electricity for someone to earn 5000 dollars worth of XMR.  You would be mad.  You would ask McAfee, or Symantec, or AVG, or Avast "How did you not catch this?"  And their answer would be, it isn't a virus, it is a mining program.

Now imagine 1000 companies of the same size or larger, who actually BUY 10,000 seats of McAfee.  A million seats, and let's say 10 dollars a seat, so 10 million dollars.  And they tell McAfee "Classify crypto currency tools as malware, detect it and remove it".  McAfee agrees, and then Symantec does, etc...

So, these AV vendors are protecting their PAYING customers by default.  I have not paid for AV in 10 years, there are good free versions, but even those now catch crypto currency tools.

So, as long as you only download miners from known good, trusted sources, you should be fine to exclude them from your AV and Browser.