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.

Protecting yourself and family from mosquito bites can be challenging, especially in this hot and humid weather. Protests from young children and fears about topical insect repellents drive some to try alternatives such as wristbands, patches and stickers.

These products are sold online as well as in supermarkets, pharmacies and camping stores. They’re often marketed as providing “natural” protection from mosquitoes.

But unfortunately, they aren’t a reliable way to prevent mosquito bites. Here’s why – and what you can try instead.

Why is preventing mosquito bites important?

Mosquitoes can spread pathogens that make us sick. Japanese encephalitis and Murray Valley encephalitis viruses can have potentially fatal outcomes. While Ross River virus won’t kill you, it can cause potentially debilitating illnesses.

Health authorities recommend preventing mosquito bites by: avoiding areas and times of the day when mosquitoes are most active; covering up with long sleeved shirts, long pants, and covered shoes; and applying a topical insect repellent (a cream, lotion, or spray).

I don’t want to put sticky and smelly repellents on my skin!

While for many people, the “sting” of a biting mosquitoes is enough to prompt a dose of repellent, others are reluctant. Some are deterred by the unpleasant feel or smell of insect repellents. Others believe topical repellents contain chemicals that are dangerous to our health.

However, many studies have shown that, when used as recommended, these products are safe to use. All products marketed as mosquito repellents in Australia must be registered by the Australian Pesticides and Veterinary Medicines Authority; a process that provides recommendations for safe use.

How do topical repellents work?

While there remains some uncertainty about how the chemicals in topical insect repellents actually work, they appear to either block the sensory organs of mosquitoes that drive them to bite, or overpower the smells of our skin that helps mosquitoes find us.

Diethytolumide (DEET) is a widely recommended ingredient in topical repellents. Picaridin and oil of lemon eucalyptus are also used and have been shown to be effective and safe.

How do other products work?

“Physical” insect-repelling products, such as wristbands, coils and candles, often contain a botanically derived chemical and are often marketed as being an alternative to DEET.

However, studies have shown that devices such as candles containing citronella oil provide lower mosquito-bite prevention than topical repellents.

A laboratory study in 2011 found wristbands infused with peppermint oil failed to provide full protection from mosquito bites.

Even as topical repellent formulations applied to the skin, these botanically derived products have lower mosquito bite protection than recommended products such as those containing DEET, picaridin and oil of lemon eucalyptus.

Wristbands infused with DEET have shown mixed results but may provide some bite protection or bite reduction. DEET-based wristbands or patches are not currently available in Australia.

There is also a range of mosquito repellent coils, sticks, and other devices that release insecticides (for example, pyrethroids). These chemicals are primarily designed to kill or “knock down” mosquitoes rather than to simply keep them from biting us.

What about stickers and patches?

Although insect repellent patches and stickers have been available for many years, there has been a sudden surge in their marketing through social media. But there are very few scientific studies testing their efficacy.

Our current understanding of the way insect repellents work would suggest these small stickers and patches offer little protection from mosquito bites.

At best, they may reduce some bites in the way mosquito coils containing botanical products work. However, the passive release of chemicals from the patches and stickers is likely to be substantially lower than those from mosquito coils and other devices actively releasing chemicals.

One study in 2013 found a sticker infused with oil of lemon eucalyptus “did not provide significant protection to volunteers”.

Clothing impregnated with insecticides, such as permethrin, will assist in reducing mosquito bites but topical insect repellents are still recommended for exposed areas of skin.

Take care when using these products

The idea you can apply a sticker or patch to your clothing to protect you from mosquito bites may sound appealing, but these devices provide a false sense of security. There is no evidence they are an equally effective alternative to the topical repellents recommended by health authorities around the world. It only takes one bite from a mosquito to transmit the pathogens that result in serious disease.

It is also worth noting that there are some health warnings and recommendations for their use required by Australian Pesticides and Veterinary Medicines Authority. Some of these products warn against application to the skin (recommending application to clothing only) and to keep products “out of reach of children”. This is a challenge if attached to young children’s clothing.

Similar warnings are associated with most other topical and non-topical mosquito repellents. Always check the labels of these products for safe use recommendations.

Are there any other practical alternatives?

Topical insect repellents are safe and effective. Most can be used on children from 12 months of age and pose no health risks. Make sure you apply the repellent as a thin even coat on all exposed areas of skin.

But you don’t need “tropical strength” repellents for short periods of time outdoors; a range of formulations with lower concentrations of repellent will work well for shorter trips outdoors. There are some repellents that don’t smell as strong (for example, children’s formulations, odourless formulations) or formulations that may be more pleasant to use (for example, pump pack sprays).

Finally, you can always cover up. Loose-fitting long-sleeved shirts, long pants, and covered shoes will provide a physical barrier between you and mosquitoes on the hunt for your or your family’s blood this summer.

Cameron Webb, Clinical Associate Professor and Principal Hospital Scientist, University of Sydney

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

We’re living longer than in previous generations, with one in eight elderly Australians now aged over 85. But the current gap between life expectancy (“lifespan”) and health-adjusted life expectancy (“healthspan”) is about ten years. This means many of us live with significant health problems in our later years.

To increase our healthspan, we need planned, structured and regular physical activity (or exercise). The World Health Organization recommends 150–300 minutes of moderate-intensity exercise – such as brisk walking, cycling and swimming – per week and muscle strengthening twice a week.

Yet few of us meet these recommendations. Only 10% meet the strength-training recommendations. Lack of time is one of the most common reasons.

Walking is cost-effective, doesn’t require any special equipment or training, and can be done with small pockets of time. Our preliminary research, published this week, shows there are ways to incorporate strength-training components into walking to improve your muscle strength and balance.

Why walking isn’t usually enough

Regular walking does not appear to work as muscle-strengthening exercise.

In contrast, exercises consisting of “eccentric” or muscle-lengthening contractions improve muscle strength, prevent muscle wasting and improve other functions such as balance and flexibility.

Typical eccentric contractions are seen, for example, when we sit on a chair slowly. The front thigh muscles lengthen with force generation.

Our research

Our previous research found body-weight-based eccentric exercise training, such as sitting down on a chair slowly, improved lower limb muscle strength and balance in healthy older adults.

We also showed walking down stairs, with the front thigh muscles undergoing eccentric contractions, increased leg muscle strength and balance in older women more than walking up stairs. When climbing stairs, the front thigh muscles undergo “concentric” contractions, with the muscles shortening.

It can be difficult to find stairs or slopes suitable for eccentric exercises. But if they could be incorporated into daily walking, lower limb muscle strength and balance function could be improved.

This is where the idea of “eccentric walking” comes into play. This means inserting lunges in conventional walking, in addition to downstairs and downhill walking.

In our new research, published in the European Journal of Applied Physiology, we investigated the effects of eccentric walking on lower limb muscle strength and balance in 11 regular walkers aged 54 to 88 years.

The intervention period was 12 weeks. It consisted of four weeks of normal walking followed by eight weeks of eccentric walking.

The number of eccentric steps in the eccentric walking period gradually increased over eight weeks from 100 to 1,000 steps (including lunges, downhill and downstairs steps). Participants took a total of 3,900 eccentric steps over the eight-week eccentric walking period while the total number of steps was the same as the previous four weeks.

We measured the thickness of the participants’ front thigh muscles, muscle strength in their knee, their balance and endurance, including how many times they could go from a sitting position to standing in 30 seconds without using their arms. We took these measurements before the study started, at four weeks, after the conventional walking period, and at four and eight weeks into the eccentric walking period.

We also tested their cognitive function using a digit symbol-substitution test at the same time points of other tests. And we asked participants to complete a questionnaire relating to their activities of daily living, such as dressing and moving around at home.

Finally, we tested participants’ blood sugar, cholesterol levels and complement component 1q (C1q) concentrations, a potential marker of sarcopenia (muscle wasting with ageing).

What did we find?

We found no significant changes in any of the outcomes in the first four weeks when participants walked conventionally.

From week four to 12, we found significant improvements in muscle strength (19%), chair-stand ability (24%), balance (45%) and a cognitive function test (21%).

Serum C1q concentration decreased by 10% after the eccentric walking intervention, indicating participants’ muscles were effectively stimulated.

The sample size of the study was small, so we need larger and more comprehensive studies to verify our findings and investigate whether eccentric walking is effective for sedentary people, older people, how the different types of eccentric exercise compare and the potential cognitive and mental health benefits.

But, in the meantime, “eccentric walking” appears to be a beneficial exercise that will extend your healthspan. It may look a bit eccentric if we insert lunges while walking on the street, but the more people do it and benefit from it, the less eccentric it will become.

Ken Nosaka, Professor of Exercise and Sports Science, Edith Cowan University

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