Introduction: Enteroviruses, such as norovirus and rotavirus, can be spread by eating some foods or liquids that have been contaminated with feces containing the virus. But recently, some scientists have confirmed that this type of enterovirus also has a way of saliva transmission.
Scientists at the National Institutes of Health have discovered that a type of enterovirus that causes severe diarrheal disease can grow in the salivary glands of mice and spread through saliva. The findings suggest a new route of transmission for these deadly common viruses that afflict billions of people around the world each year.
The ability of these enteroviruses to spread through saliva suggests that coughing, talking, sneezing, sharing food and utensils, and even kissing have the potential to spread the virus. But this has yet to be confirmed in humans.
The research, led by the NIH-affiliated National Heart, Lung, and Blood Institute (NHLBI), may lead to better ways to prevent, diagnose and treat diseases caused by these viruses, and possibly even save a lot of lives. The findings were published in the journal Nature. https://www.nature.com/articles/s41586-022-04895-8
Researchers know that enteroviruses, such as norovirus and rotavirus, can be spread by eating some foods or liquids that have been contaminated with virus-containing feces. We used to think that enteroviruses skip the salivary glands, target only the gut, and are subsequently excreted in the feces. Although some scientists have suspected that there may be another transmission route, this theory has so far not been tested.
Now, researchers need to show that it is possible for enteroviruses to spread through saliva in humans. If confirmed, the researchers say, this route of transmission may also be found to be even more common than the traditional route of transmission.
Altan-Bonnet, who has studied enteroviruses for many years, said the discovery was entirely accidental. Her team has been experimenting with enteroviruses in young mice. The immature digestive and immune systems of young mice make them susceptible to infection, making them the animal model of choice for research.
In the experiment, the researchers fed a group of newborn mice less than 10 days old with norovirus and rotavirus. They then returned the pups to their cages and had them suck on breast milk from their virus-free mothers. Just one day later, team member Dr. Sourish Ghosh noticed something unusual: a surge in IgA antibodies, an important disease-fighting component, in the guts of young mice. This is rather surprising, since the immune systems of young mice are immature and cannot produce their own antibodies at this stage.
In addition, Ghosh noticed that the virus replicated abundantly in the mother’s breast tissue (the milk duct cells). When Ghosh collected breast milk from the udders of rat mothers, he found that the timing and levels of IgA surges in breast milk coincided with the timing and levels of IgA surges in the guts of pups. Infections in the mother’s breast appeared to boost the production of IgA antibodies in breast milk, which ultimately helped clear the infection in pups, the researchers said.
To understand how the virus initially entered the mother’s breast tissue, the researchers conducted an additional experiment and found that the mouse pups did not transmit the virus to their mothers by the traditional route — through contaminated feces Stay in a shared living space for their mother to ingest. They set out to investigate whether the virus in the mother’s breast tissue might have come from the pups’ saliva and somehow spread during lactation.
To test this conjecture, Ghosh collected saliva samples and salivary glands from young mice and found that the salivary glands replicated the viruses at very high levels and shed the virus in large quantities into their saliva. This additional experiment quickly confirmed the saliva theory: breastfeeding causes virus transmission between mother and baby.
Senior author Nihal Altan-Bonnet, Ph.D., director of NHLBI’s Laboratory of Host-Pathogen Dynamics, said: “This is an entirely new field because we previously thought these viruses could only grow in the gut. Saliva transmission of enteroviruses is something we didn’t know yet. Another level of transmission. We need to rethink how these viruses are transmitted and diagnosed, but most importantly, how to slow their spread.”

On June 30, 2022, researchers at the University of California, Los Angeles published a study in the Cell journal iScience titled: Accelerated aging with HIV begins at the time of initial HIV infection.
The study suggests that HIV accelerates age-related biological changes in the body in just 2-3 years after infection. People infected with HIV have a life expectancy nearly five years shorter than those uninfected.

The team said HIV initiates the process of accelerated aging at the DNA level in the early days after infection. This finding highlights the importance of early diagnosis of HIV and understanding of aging-related issues, as well as the importance and value of preventing HIV infection.
Previous studies have linked HIV and antiretroviral therapy, commonly used to control infection, to the early onset of age-related diseases, such as heart disease, kidney disease, frailty and cognitive impairment.
The team analysed blood samples collected and stored from 100 men six months or less before they were infected with HIV and again two to three years after infection. The blood samples were then compared with those from 100 uninfected men of the same age at the same time. All were participants in a multicenter COHORT of AIDS studies, a national study that ran from 1984 to 2019. It is also the first study to compare HIV-infected and uninfected people in this way.
The research team focused on how HIV affects epigenetic DNA methylation, a modification that cells use to turn genes on and off during normal physiological changes. Epigenetic changes are changes that occur in response to the influence of the environment, behavior, or other external factors, such as disease. These changes do not affect the DNA sequence, but can affect how genes are expressed through DNA methylation.
The team assessed the participants for five epigenetic changes, four of which were so-called epigenetic clocks, each using a slightly different approach to assessing biological age relative to actual age, where DNA methylation levels increase with age. The fifth assessment is based on telomere length. The length of telomeres gradually decreases with age.
The results showed that all hiv-infected individuals showed accelerated aging on all four epigenetic clocks between pre-infection and two to three years post-infection, with an accelerated average biological age of 1.9 to 4.8 years and shortened telomeres. Participants who were not infected with HIV did not see a similar acceleration in biological age over the same time interval.

The next goal, the team says, is to determine whether these traits can predict whether a person is at risk for age-related diseases, thus providing new directions for intervention and treatment.

Introduction: Since 2019, the new crown epidemic began to spread, and now it can be said that it has become a normalization. The culprit of this outbreak is undoubtedly the “coronavirus”. What is overwhelming is the constant mutation of this virus, which has led to the fact that the antibodies studied in humans cannot be fully immune for the time being.

 

There are a variety of organisms on our earth, and viruses are one of them. At the same time, because of the existence of the virus, it poses a certain threat to the life and health of other life forms on the earth.

1. Definition of virus and structure of virus

We all know that almost all of us humans and the vast majority of organisms are dual-core inheritance, using DNA as genetic information. But the virus is different. It is only composed of a nucleic acid molecule, that is, it only has deoxyribonucleotides (DNA) or only ribonucleotides (RNA), and then binds to the form formed by proteins (non-cellular) . Its size is very small, much smaller than bacteria.

 

Viruses also have a relatively diverse structure, such as decahedron, spiral, etc. The structure of a virus is a protein coat that surrounds the nucleotides that represent its genetic information. The survival and reproduction of viruses mainly rely on parasitism in other cell species. Therefore, whether a virus is a living organism or not, the scientific community’s definition of it is relatively vague.

At the same time, viruses are not classified into the five categories of protists, prokaryotes, fungi, animals and plants. The reproduction mode of the virus is completed in its host cell, using the proteins in the host cell and the continuous replication of its own genetic information.

Viruses cannot grow and reproduce independently of host cells. Its infectious ability is extremely strong, and it can infect almost all organisms with cellular structures. However, some people ask what is the origin of the specific virus? Now the scientific community is also scratching their heads (currently, it is relatively accepted that viruses originated from plasmids and bacteria).

 

2. Virus reproduction mechanism and process

We briefly mentioned above that virus reproduction, in fact, virus replication refers to a process in which viruses invade host cells and then release genetic information. The whole process includes virus adsorption, genetic information entry, gene expression, and genetic information. replication, binding to proteins, and release of large amounts of virus. There may be slight differences depending on the type of virus.

1. Adsorption and entry of viruses

Taking T4 phage as an example, the virus first binds to the receptor on the surface of E. coli, and then penetrates the membrane structure of E. coli through the tail shaft, and transfers the genetic information (DNA or RNA) inside the protein to the inside of E. coli.

 

2. Expression of viral genes

After the genetic information of the virus enters E. coli, the genetic information is translated in E. coli by means of transcription to form a large number of corresponding proteins (including enzyme substances and protein structures). This series of processes is also known as gene expression.

 

3. Virus transcription

Virus transcription is mainly carried out in six ways. The way of transcription is almost the same as that of host cells. It needs to transcribe messenger RNA through the process of double-strand formation, and then translate it to form a new genetic information. There are different ways of transcription according to different viral nucleic acid types.

 

3. Why do viruses mutate so frequently and what drives them to mutate

I believe everyone must have heard the word “gene mutation”. Gene mutation occurs in all organisms, and human beings will also have gene mutation. At the same time, it is precisely because of gene mutation that the evolution and development of organisms are caused. Similarly, the mutation of the virus is also due to the existence of genetic mutation.

That’s why virus mutations can be so frequent, while other species’ mutations are rare. First of all, the genetic information of human organisms is determined by DNA, and DNA has a double-helix structure. This structure is very stable, and some purines are not prone to mutation, etc., which also leads to DNA double-stranded structure of biological genes Mutations are rare.

The virus is different. Its genetic information includes DNA and RNA. However, they are all single-stranded structures. Relatively speaking, they are extremely unstable and easy to mutate, even caused by purine pairing errors. Therefore, virus mutation will be more frequent.

 

Write at the end. To sum up, the variability of the virus is determined by its special structure and growth and reproduction. For example, our current new crown virus has mutated nearly 240 viruses such as “Omicron virus” and “beta virus”.

It can be seen that, in view of the current anxious situation of the global epidemic, it is necessary to prevent not only the existing strains, but also the harm caused by the strains that may be mutated. Therefore, readers and friends, if you are interested in the new coronavirus, you can do more research on the mutation mechanism and reproduction mechanism of the virus.

For the first time, immunologists have obtained clear images of glycoproteins. The protein, which plays a key role in the pathogenesis of rabies, will help create a more effective vaccine against the deadly disease, according to a study by scientists in the United States and France published in the journal Science Advances.

Rabies virus has a high fatality rate

The Russian news agency reported that the rabies virus is one of the most dangerous viruses in the world. The mortality rate during the onset of clinical symptoms is 100%. Every year, 59,000 people die from the disease, and about 40 percent of those infected are children.

The main way to stop the spread of infection is to vaccinate pets (mostly dogs), which release the virus 99% of the time. However, existing drugs have an important disadvantage: they do not provide life-long protection. Pets need to be vaccinated every one to three years.