The hepatitis D virus possesses the smallest known human genome—only about 1,680 nucleotides encoding essentially a single protein. Yet from this remarkably limited genetic information emerges a molecular system capable of regulating genome copying, altering its developmental state, exploiting dozens of cellular pathways, and assembling new virus particles with extraordinary precision. The sophistication of HDV does not arise because either its RNA or its protein is independe

The hepatitis D virus RNA genome is continuously moving and negotiating interactions with other molecules. It is constantly sampling its own possible shapes while simultaneously engaging in dialogue with proteins that would respond to each of these shapes. These RNA shapes also interact with ions, water, and the three-dimensional architecture of the cell. To understand hepatitis D virus RNA is to appreciate that a single circular molecule of 1,680 nucleotides can simultaneous

Hepatitis D virus produces essentially one protein—hepatitis delta antigen—in two closely related forms: the 195-amino-acid small antigen and the 214-amino-acid large antigen. Yet from this single gene emerges a molecular system capable of entering the nucleus, organizing viral RNA, exploiting cell RNA polymerases, recruiting genome copying and RNA-processing machinery, undergoing regulatory modifications, switching between genome copying and assembly, binding the envelope pr

It is impossible to exactly define what intelligence would be in a molecule or complex molecular system. The Turing test is used to determine if a machine can match the intelligence of humans, but is inexact. Can we think of a version of a Turing test to consider if hepatitis D virus, the smallest human virus, is intelligent. For the details of hepatitis D virus' very complex lifestyle please refer to the previous post Smallest Human Virus – Very Dangerous, Very Intelligent

Hepatitis D virus, also called hepatitis delta virus, is one of the strangest human viruses. Its genome is a tiny circular single-stranded RNA of only about 1,700 nucleotides, and it produces essentially one protein in two forms—the small and large hepatitis delta antigens. It does not encode its own enzyme to copy its RNA as most RNA viruses do. It doesn’t produce its own envelope proteins or most of the machinery normally associated with a virus. Instead, it has an extraord

RNA is a structural molecule whose three-dimensional architecture stores biological information, interacts with cellular proteins, catalyzes chemical reactions, and coordinates an infectious life cycle. It carries out these actions through precise three-dimensional structures capable of recognizing and binding other molecules with high specificity. What is less widely appreciated is that RNA achieves this wide range of interactions not despite its constant movement, but becau

A viroid is smaller than a virus. It is a strand of RNA with 246 to 467 nucleotides in length. It is single-stranded, with extensive self-bonding between bases and forms into a fluctuating rod-like or branched structure. It does not produce proteins, has no capsid or membrane, and hijacks cell enzymes to copy itself with a circular rolling mechanism. Thus far, viroids are only found in plants. Also, they can contain ribozymes, which are RNA regions that are able to accuratel

The first signals from bacteria communicating to fellow comrades were discovered in the 1960s. It took 60 years of research to realize the intelligence of bacteria. The first virus signal was discovered in 2017 and in the nine years since then a vast amount of information has been discovered about virus communication. Much of the research has been in phage viruses––viruses that interact with and inhabit bacteria. It is clear now that phage viruses are not making decisions ba

It is only recently that scientists have been able to observe tiny viruses and their behavior. Bacteria are a thousand times larger than viruses, and our human cells are a thousand times larger than bacteria. We still don’t know what viruses are and how they can have such a complex lifestyle while consisting of just a piece of RNA or DNA and a handful of proteins. With everyone focused on SARS-CoV-2 virus, it is important to realize that much is being learned about how viruse

Some think viruses are not alive. It is, therefore, very surprising that they can evade elaborate cellular mechanisms used to find and destroy them. Search and destroy mechanisms of the cell and counter attacks from viruses are very complex. Cells use many sensors to find DNA and RNA that is not where it is supposed to be. When found, other mechanisms are triggered to get rid of it. Major cellular tools are pattern recognition receptors with enormous numbers of variations all

Only a very small percentage of the world’s microbes have been discovered, and even less of the much more plentiful and diverse viruses. So, it is not surprising that many dramatic new viruses have recently been found that alter our understanding of evolution. The giant Pandora viruses and many new unique ocean phages have brought forth questions about the validity of the current three-limbed diagram of the tree of life (archaea, bacteria, eukarya). With viruses and virus lik

50% of the human genome consists of jumping genes or mobile genetic elements. The 8% of human DNA from retroviruses has been vital to human evolution, such as determining the human placenta, epigenetic changes in the brain and digestive enzymes. An epigenetic immune system in the nucleus battles the jumping genes for control of the cell and control of evolution. Jumping genes, being large strands of DNA with specific functions, are much more likely to be the drivers of evol

One of the first discoveries about the unusual behavior and cognitive abilities of bacteria was a signal put out by many of the members of a community to make a group decision. This "quorum sensing" signal stimulates collaborative attacks and migration by sensing if there are enough providing signals to carry out the activity. Later, it was learned that each bacterium has many remarkable communication skills that allow them to manipulate the much larger and more complex human

It is quite remarkable how much viruses can accomplish with a very small number of genes and a handful of proteins. Previous posts have described the very elaborate lifestyle of HIV with only 9 genes, and Ebola with only 7 genes. Somehow, viruses are able to manipulate vast cellular machinery including organelles much larger than them. They are able to manipulate actin scaffolding for their purposes. They can fool the nuclear pores into allowing them in. They take over the en

Several intelligent viruses have been featured in previous posts. Herpes has a very complex life style with more than 70 genes—traveling up and down the neuron and in and out of the skin cell. HIV has an extraordinary set of complex behaviors with only 9 genes—travelling with critical proteins in its capsid, evading immune cells with multiple techniques and manipulating the cell’s complex nuclear machinery. How all of this can be accomplished with only 9 genes is not clear. N

Several posts have documented the unusual complex behavior of viruses. In particular, a recent post, The Remarkable Intelligent Varicella Virus, described a wide range of different complex behaviors for this small herpes virus. Somehow, it is able to enter and exit skin and nerve cells; travel up and down along the microtubules of the axons by commandeering the motors; move in and out of the cell’s nucleus; and alter its own behavior in different circumstances. The varicella

Varicella zoster virus is an alpha herpes virus that has been described in a previous post as having remarkable capabilities and a very complex lifestyle—the ability to travel up and down axons in a neuron, to move in and out of several different types of cells, to travel and multiply in T cells, to fool several different nuclear pore complexes, to commandeer microtubule motors, and to alter its own behavior pattern in different settings. How can the remarkable intelligent va

Evidence of intelligent behavior in subcellular structures.