We tend to just think of viruses in terms of their damaging impacts on human health and lives. The 1918 flu pandemic killed around 50 million people. Smallpox claimed 30% of those who caught it, and survivors were often scarred and blinded. More recently, we’re all too familiar with the health and economic impacts of COVID.

But viruses can also be used to benefit human health, agriculture and the environment.

Viruses are comparatively simple in structure, consisting of a piece of genetic material (RNA or DNA) enclosed in a protein coat (the capsid). Some also have an outer envelope.

Viruses get into your cells and use your cell machinery to copy themselves.
Here are six ways we’ve harnessed this for health care and pest control.

1. To correct genes

Viruses are used in some gene therapies to correct malfunctioning genes. Genes are DNA sequences that code for a particular protein required for cell function.

If we remove viral genetic material from the capsid (protein coat) we can use the space to transport a “cargo” into cells. These modified viruses are called “viral vectors”.

Viral vectors can deliver a functional gene into someone with a genetic disorder whose own gene is not working properly.

Some genetic diseases treated this way include haemophilia, sickle cell disease and beta thalassaemia.

2. Treat cancer

Viral vectors can be used to treat cancer.

Healthy people have p53, a tumour-suppressor gene. About half of cancers are associated with the loss of p53.

Replacing the damaged p53 gene using a viral vector stops the cancerous cell from replicating and tells it to suicide (apoptosis).

Viral vectors can also be used to deliver an inactive drug to a tumour, where it is then activated to kill the tumour cell.

This targeted therapy reduces the side effects otherwise seen with cytotoxic (cell-killing) drugs.

We can also use oncolytic (cancer cell-destroying) viruses to treat some types of cancer.

Tumour cells have often lost their antiviral defences. In the case of melanoma, a modified herpes simplex virus can kill rapidly dividing melanoma cells while largely leaving non-tumour cells alone.

3. Create immune responses

Viral vectors can create a protective immune response to a particular viral antigen.

One COVID vaccine uses a modified chimp adenovirus (adenoviruses cause the common cold in humans) to transport RNA coding for the SARS-CoV-2 spike protein into human cells.

The RNA is then used to make spike protein copies, which stimulate our immune cells to replicate and “remember” the spike protein.

Then, when you are exposed to SARS-CoV-2 for real, your immune system can churn out lots of antibodies and virus-killing cells very quickly to prevent or reduce the severity of infection.

4. Act as vaccines

Viruses can be modified to act directly as vaccines themselves in several ways.

We can weaken a virus (for an attenuated virus vaccine) so it doesn’t cause infection in a healthy host but can still replicate to stimulate the immune response. The chickenpox vaccine works like this.

The Salk vaccine for polio uses a whole virus that has been inactivated (so it can’t cause disease).

Others use a small part of the virus such as a capsid protein to stimulate an immune response (subunit vaccines).

An mRNA vaccine packages up viral RNA for a specific protein that will stimulate an immune response.

5. Kill bacteria

Viruses can – in limited situations in Australia – be used to treat antibiotic-resistant bacterial infections.

Bacteriophages are viruses that kill bacteria. Each type of phage usually infects a particular species of bacteria.

Unlike antibiotics – which often kill “good” bacteria along with the disease-causing ones – phage therapy leaves your normal flora (useful microbes) intact.

6. Target plant, fungal or animal pests

Viruses can be species-specific (infecting one species only) and even cell-specific (infecting one type of cell only).

This occurs because the proteins viruses use to attach to cells have a shape that binds to a specific type of cell receptor or molecule, like a specific key fits a lock.

The virus can enter the cells of all species with this receptor/molecule. For example, rabies virus can infect all mammals because we share the right receptor, and mammals have other characteristics that allow infection to occur whereas other non-mammal species don’t.

When the receptor is only found on one cell type, then the virus will infect that cell type, which may only be found in one or a limited number of species. Hepatitis B virus successfully infects liver cells primarily in humans and chimps.

We can use that property of specificity to target invasive plant species (reducing the need for chemical herbicides) and pest insects (reducing the need for chemical insecticides). Baculoviruses, for example, are used to control caterpillars.

Similarly, bacteriophages can be used to control bacterial tomato and grapevine diseases.

Other viruses reduce plant damage from fungal pests.

Myxoma virus and calicivirus reduce rabbit populations and their environmental impacts and improve agricultural production.

Just like humans can be protected against by vaccination, plants can be “immunised” against a disease-causing virus by being exposed to a milder version.

Thea van de Mortel, Professor, Nursing, School of Nursing and Midwifery, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

So you’ve got yourself a gym membership or bought a set of home weights. Now what? With the sheer amount of confusing exercise advice out there, it can be hard to decide what to include in a weights routine.

It can help to know there are broadly two types of movements in resistance training (lifting weights): compound exercises and isolation exercises.

So what’s the difference? And what’s all this got to do with strength, speed and healthy ageing?

What’s the difference?

Compound exercises involve multiple joints and muscle groups working together.

In a push up, for example, your shoulder and elbow joints are moving together. This targets the muscles in the chest, shoulder and triceps.

When you do a squat, you’re using your thigh and butt muscles, your back, and even the muscles in your core.

It can help to think about compound movements by grouping them by primary movement patterns.

For example, some lower body compound exercises follow a “squat pattern”. Examples include bodyweight squats, weighted squats, lunges and split squats.

We also have “hinge patterns”, where you hinge from a point on your body (such as the hips). Examples include deadlifts, hip thrusts and kettle bell swings.

Upper body compounded exercises can be grouped into “push patterns” (such as vertical barbell lifts) or “pull patterns” (such as weighted rows, chin ups or lat pull downs, which is where you use a pulley system machine to lift weights by pulling a bar downwards).

In contrast, isolation exercises are movements that occur at a single joint.

For instance, bicep curls only require movement at the elbow joint and work your bicep muscles. Tricep extensions and lateral raises are other examples of isolation exercises.

Compound exercises can make daily life easier

Many compound exercises mimic movements we do every day.

Hinge patterns mimic picking something off the floor. A vertical press mimics putting a heavy box on a high shelf. A squat mimics standing up from the couch or getting on and off the toilet.

That might sound ridiculous to a young, fit person (“why would I need to practise getting on and off a toilet?”).

Unfortunately, we lose strength and muscle mass as we age. Men lose about 5% of their muscle mass per decade, while for women the figure is about 4% per decade.

When this decline begins can vary widely. However, approximately 30% of an adult’s peak muscle mass is lost by the time they are 80.

The good news is resistance training can counteract these age-related changes in muscle size and strength.

So building strength through compound exercise movements may help make daily life feel a bit easier. In fact, our ability to perform compound movements are a good indicator how well we can function as we age.

What about strength and athletic ability?

Compound exercises use multiple joints, so you can generally lift heavier weights than you could with isolation exercises. Lifting a heavier weight means you can build muscle strength more efficiently.

One study divided a group of 36 people into two. Three times a week, one group performed isolation exercises, while the other group did compound exercises.

After eight weeks, both groups had lost fat. But the compound exercises group saw much better results on measures of cardiovascular fitness, bench press strength, knee extension strength, and squat strength.

If you play a sport, compound movements can also help boost athletic ability.

Squat patterns require your hip, knee, and ankle to extend at the same time (also known as triple extension).

Our bodies use this triple extension trick when we run, sprint, jump or change direction quickly. In fact, research has found squat strength is strongly linked to being able to sprint faster and jump higher.

Isolation exercises are still good

What if you’re unable to do compound movements, or you just don’t want to?

Don’t worry, you’ll still build strength and muscle with isolation exercises.

Isolation exercises are also typically easier to learn as there is no skill required. They are an easy and low risk way to add extra exercise at the end of the workout, where you might otherwise be too tired to do more compound exercises safely and with correct form.

In fact, both isolation and compound exercises seem to be equally effective in helping us lose body fat and increase fat-free muscle mass when total intensity and volume of exercises are otherwise equal.

Some people also do isolation exercises when they want to build up a particular muscle group for a certain sport or for a bodybuilding competition, for example.

I just want a time efficient workout

Considering the above factors, you could consider prioritising compound exercises if you’re:

• time poor
• keen to lift heavier weights
• looking for an efficient way to train many muscles in the one workout
• interested in healthy ageing.

That said, most well designed workout programs will include both compound and isolation movements.

Correction: This article has been amended to reflect the fact a weighted row is a pull pattern, not a push pattern.

Mandy Hagstrom, Senior Lecturer, Exercise Physiology. School of Health Sciences, UNSW Sydney and Anurag Pandit, PhD Candidate in Exercise Physiology, UNSW Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.