Do you think that your antivirus software can prevent every attack on your PC? There is no 100% guarantee, because, you can install only single Antivirus software on your computer. Different antivirus software uses different virus engine and the detection rates are also different. Some viruses will not be detected by particular antivirus.
But, if we have a virus scanner with multiple antivirus engines, virus infection can be reduced considerably. Here comes VirusTotal. If you have a suspicious file and want to check it with different antivirus engine, just upload your file, VirusTotal will scan it with 34 virus engine.
VirusTotal is a service that analyzes suspicious files and facilitates the quick detection of viruses, worms, Trojans, and all kinds of malware detected by antivirus engines.
Popular Virus engines are – Kaspersky, Bitdefender, NOD32, MacAfee, Microsoft, Panda, Norman, Avast, Rising, TrendMicro, AVG, Avira, Norton, etc – Full list
However,VirusTotal is not substitute any antivirus software installed in a PC, as it only scans individual files on demand. It does not offer permanent protection for the user's system either.
And remember that, currently, there is not any solution that offers a 100% effectiveness rate for detecting viruses and malware (source)