Eukariyotic cells are very complex. Virus do not have cellular organization.
Bacteria cells. They are the smallest living thing on Earth (known to man).
Poliomyelitis antigen is a complex compound on the surface of the virus.
Viruses can have various shapes, including helical, icosahedral, complex, or enveloped. These shapes are determined by the way the viral proteins and genetic material are arranged within the virus particle.
Technically, a virus is not considered to be alive, therefore is not an organism at all. A virus does not have a conventional membrane, unless, as with HIV, it takes some from a host cell in order to mask its presence to other cells.
A bacteriophage is a virus that infects and replicates within bacteria. It injects its genetic material into a bacterial cell, taking over the cell's machinery to produce more virus particles. Bacteriophages are being studied for their potential use in treating bacterial infections as an alternative to antibiotics.
The largest virus known is the pandoravirus, with some strains reaching up to 2 micrometers in length. These viruses have complex genomes and are larger than some bacteria.
It depends on which virus you have. Most of them can be removed with a simple scan by an antivirus program while some very complex ones will require a complex removal process usually involving several antivirus and scans with a utility such as Malwarebyte's anti malware.
I do think that a person can have more than one virus at a time because if you are in a very contaminated area then you can catch more than one virus
The complexity of a viruses it depend on their genome.Larger genome, more genes more complex structure.Their are some viruses that produce only three genes.Hepatitis D virus with 1700 nucleotides its knowed as the smallet virus that infect animals.It replicate only in presence of hepatitis B.It has an outer coat containing three HBV envelope proteins
A trojan virus is worse than a normal virus and is more likely to crash your computer
Anti-Virus,Anti-Spyware,and many more.
There is nothing wrong with having more then one anti-virus program installed on your computer. Not every virus is detected by every anti-virus program. It is actually a good idea to run more then one virus scanner.