"Lean meat" is a misleading term. I noticed many times in conversations that people who think that they eat "proteins" tend to think about this food group as an almost pure protein, a perfect set of essential amino acids. Especially if they consume so called "lean meats."
In beef (presented as "90% lean meat") - half of the calories are from fat (http://nutritiondata.self.com/facts/beef-products/6193/2). Even in the leanest bird meat approximately the fifth of the energy is from fat, ~18% in the leanest I could find (http://nutritiondata.self.com/facts/poultry-products/704/2).
Digestibility-corrected amino acid score (PDCAAS) of protein in beef is only 0.92, chicken - 0.91(?), and egg whites and soy - 1 or 100% (not that it matters much). Note, that 62% of calories in a whole egg are from fat, and 40% in soybeans.
A virus is a small infectious agent that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.
There are millions types of viruses, ~ 5,000 virus species have been described in detail. Viruses are found in almost every ecosystem and are the most abundant type of biological entity. The origins of viruses in the evolutionary history of life are unclear.
While not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent particles, virions, which consist of the genetic material made from either DNA or RNA, a protein coat, and in some cases an outer coat of lipids. Virion is about one one-hundredth the size of a bacterium.