I call virus a stress messenger. And since we all are made up of पञ्चमहाभूत & nurtured by महाप्राण, stress in environment applies to all organisms. Stress messengers i.e. Viruses too are not organism-specific but stress-specific.
Viruses share genes with organisms across the tree of life
A new study reveals that viruses share genes across the three superkingdoms of life, from the single-celled microbes known as bacteria and archaea, to eukarya, a group that includes animals, plants, fungi and all other living things. Most of this unusual sharing occurs between eukarya and bacteria and their viruses.
“We discovered many virus-hallmark genes in cellular organisms those viruses are not known to infect,” Nasir said. “This was especially obvious for bacterial viruses and eukaryotic organisms, possibly because of the greater number of ways bacteria interact with eukarya.”
“While people tend to think only about viruses that infect and kill their hosts, we have known for decades that a virus will sometimes enter into a cell and incorporate its genetic material into the cell without killing it,” Caetano-Anolles said. In the case of single-celled organisms, those genes are sometimes passed along to future generations, he said.
Do Viruses Exchange Genes across Superkingdoms of Life?
Viruses can be classified into archaeoviruses, bacterioviruses, and eukaryoviruses according to the taxonomy of the infected host. The host-constrained perception of viruses implies preference of genetic exchange between viruses and cellular organisms of their host superkingdoms and viral origins from host cells either via escape or reduction. However, viruses frequently establish non-lytic interactions with organisms and endogenize into the genomes of bacterial endosymbionts that reside in eukaryotic cells. Such interactions create opportunities for genetic exchange between viruses and organisms of non-host superkingdoms. Here, we take an atypical approach to revisit virus-cell interactions by first identifying protein fold structures in the proteomes of archaeoviruses, bacterioviruses, and eukaryoviruses and second by tracing their spread in the proteomes of superkingdoms Archaea, Bacteria, and Eukarya. The exercise quantified protein structural homologies between viruses and organisms of their host and non-host superkingdoms and revealed likely candidates for virus-to-cell and cell-to-virus gene transfers. Unexpected lifestyle-driven genetic affiliations between bacterioviruses and Eukarya and eukaryoviruses and Bacteria were also predicted in addition to a large cohort of protein folds that were universally shared by viral and cellular proteomes and virus-specific protein folds not detected in cellular proteomes. These protein folds provide unique insights into viral origins and evolution that are generally difficult to recover with traditional sequence alignment-dependent evolutionary analyses owing to the fast mutation rates of viral gene sequences.