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The most recent human retroviral infections leading to germ line integration took place with a subgroup of human endogenous retroviruses called HERVK(HML-2). The human genome contains ~90 copies of these viral genomes, which might have infected human ancestors as recently as 200,000 years ago. HERVs do not produce infectious virus: not only is the viral genome silenced - no mRNAs are produced - but they are littered with lethal mutations that have accumulated over time. A recent study revealed that HERVK mRNAs are produced during normal human embryogenesis. Viral RNAs were detected beginning at the 8-cell stage, through epiblast cells in preimplantation embryos, until formation of embryonic stem cells (illustrated). At this point the production of HERVK mRNA ceases. Viral capsid protein was detected in blastocysts, and electron microscopy revealed the presence of virus-like particles similar to those found in reconstructed HERVK particles. These results indicate that retroviral proteins and particles are present during human development, up until implantation.

The origin of viruses remains mysterious because of their diverse and patchy molecular and functional makeup. Although numerous hypotheses have attempted to explain viral origins, none is backed by substantive data. We take full advantage of the wealth of available protein structural and functional data to explore the evolution of the proteomic makeup of thousands of cells and viruses. Despite the extremely reduced nature of viral proteomes, we established an ancient origin of the "viral supergroup" and the existence of widespread episodes of horizontal transfer of genetic information. Viruses harboring different replicon types and infecting distantly related hosts shared many metabolic and informational protein structural domains of ancient origin that were also widespread in cellular proteomes. Phylogenomic analysis uncovered a universal tree of life and revealed that modern viruses reduced from multiple ancient cells that harbored segmented RNA genomes and coexisted with the ancestors of modern cells. The model for the origin and evolution of viruses and cells is backed by strong genomic and structural evidence and can be reconciled with existing models of viral evolution if one considers viruses to have originated from ancient cells and not from modern counterparts.

Can't remember every viral infection you've ever had? Don't worry, your blood can. A new test surveys the antibodies present in a person's bloodstream to reveal a history of the viruses they've been infected with throughout their life. The method could be useful not only for diagnosing current and past illnesses, but for developing vaccines and studying links between viruses and chronic disease.

This case study was inspired by the Zika virus outbreak that occurred around the time of the 2016 Olympic Games. Many athletes were fearful of attending because of the link between Zika virus infection and microcephaly in infants. This concern, however, ran contrary to reports suggesting that the risk of athletes and other travelers becoming infected was remarkably low. Jessica, a fictional Olympic equestrian and the main character of the case, was unfortunately very unlucky and contracted Zika virus near the time of the Games. She ended up enduring negative health complications likely as a consequence of the infection.  This case was designed to be implemented in the nervous system unit of a human biology or anatomy and physiology course. The case is also appropriate for microbiology and public health courses.   Students are expected to have foundational knowledge in viral life cycles, and will explore disruptions in neurotransmission as well as abnormal fetal brain development.

Khan Academy Lytic and Lysogenic viral cycles 5:10 video

An exciting new test might help us save antibiotics. Needing only a drop of blood, researchers at Duke have developed a rapid assay that can tell viral infections-which generally can't be treated-from bacterial ones that may benefit from antibiotics. While I don't usually write about drugs or products in development, this test piqued my interest and left me excited about its potential to help contain antibiotic overuse.

The table below displays the list of human viral pathogens, with transmission and general facts about associated pathologies.

Our genomes are riddled with the detritus of ancient viruses. They infected our hominid ancestors tens of millions of years ago, inserting their genes into the DNA of their hosts. Today, we carry about 100,000 genetic remnants of this invasion. So-called endogenous retroviruses make up 8 percent of the human genome.

The test, dubbed VirScan, and research surrounding it is the subject of a new report published in the journal Science. For the study, scientists screened sera, a part of the blood, from 569 people in the U.S., South Africa, Thailand, and Peru and tested for more than 200 types of viruses.

Hank tells us the stories of three experiments in biology that, with creativity and luck, changed science & the world with it in their work to solve the mysteries of the universe.