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.

In recent years, there’s been increasing hype about the potential health risks associated with so-called “ultra-processed” foods.

But new evidence published this week found not all “ultra-processed” foods are linked to poor health. That includes the mass-produced wholegrain bread you buy from the supermarket.

While this newly published research and associated editorial are unlikely to end the wrangling about how best to define unhealthy foods and diets, it’s critical those debates don’t delay the implementation of policies that are likely to actually improve our diets.

What are ultra-processed foods?

Ultra-processed foods are industrially produced using a variety of processing techniques. They typically include ingredients that can’t be found in a home kitchen, such as preservatives, emulsifiers, sweeteners and/or artificial colours.

Common examples of ultra-processed foods include packaged chips, flavoured yoghurts, soft drinks, sausages and mass-produced packaged wholegrain bread.

In many other countries, ultra-processed foods make up a large proportion of what people eat. A recent study estimated they make up an average of 42% of total energy intake in Australia.

How do ultra-processed foods affect our health?

Previous studies have linked increased consumption of ultra-processed food with poorer health. High consumption of ultra-processed food, for example, has been associated with a higher risk of type 2 diabetes, and death from heart disease and stroke.

Ultra-processed foods are typically high in energy, added sugars, salt and/or unhealthy fats. These have long been recognised as risk factors for a range of diseases.

It has also been suggested that structural changes that happen to ultra-processed foods as part of the manufacturing process may lead you to eat more than you should. Potential explanations are that, due to the way they’re made, the foods are quicker to eat and more palatable.

It’s also possible certain food additives may impair normal body functions, such as the way our cells reproduce.

Is it harmful? It depends on the food’s nutrients

The new paper just published used 30 years of data from two large US cohort studies to evaluate the relationship between ultra-processed food consumption and long-term health. The study tried to disentangle the effects of the manufacturing process itself from the nutrient profile of foods.

The study found a small increase in the risk of early death with higher ultra-processed food consumption.

But importantly, the authors also looked at diet quality. They found that for people who had high quality diets (high in fruit, vegetables, wholegrains, as well as healthy fats, and low in sugary drinks, salt, and red and processed meat), there was no clear association between the amount of ultra-processed food they ate and risk of premature death.

This suggests overall diet quality has a stronger influence on long-term health than ultra-processed food consumption.

When the researchers analysed ultra-processed foods by sub-category, mass-produced wholegrain products, such as supermarket wholegrain breads and wholegrain breakfast cereals, were not associated with poorer health.

This finding matches another recent study that suggests ultra-processed wholegrain foods are not a driver of poor health.

The authors concluded, while there was some support for limiting consumption of certain types of ultra-processed food for long-term health, not all ultra-processed food products should be universally restricted.

Should dietary guidelines advise against ultra-processed foods?

Existing national dietary guidelines have been developed and refined based on decades of nutrition evidence.

Much of the recent evidence related to ultra-processed foods tells us what we already knew: that products like soft drinks, alcohol and processed meats are bad for health.

Dietary guidelines generally already advise to eat mostly whole foods and to limit consumption of highly processed foods that are high in refined grains, saturated fat, sugar and salt.

But some nutrition researchers have called for dietary guidelines to be amended to recommend avoiding ultra-processed foods.

Based on the available evidence, it would be difficult to justify adding a sweeping statement about avoiding all ultra-processed foods.

Advice to avoid all ultra-processed foods would likely unfairly impact people on low-incomes, as many ultra-processed foods, such as supermarket breads, are relatively affordable and convenient.

Wholegrain breads also provide important nutrients, such as fibre. In many countries, bread is the biggest contributor to fibre intake. So it would be problematic to recommend avoiding supermarket wholegrain bread just because it’s ultra-processed.

So how can we improve our diets?

There is strong consensus on the need to implement evidence-based policies to improve population diets. This includes legislation to restrict children’s exposure to the marketing of unhealthy foods and brands, mandatory Health Star Rating nutrition labelling and taxes on sugary drinks.

These policies are underpinned by well-established systems for classifying the healthiness of foods. If new evidence unfolds about mechanisms by which ultra-processed foods drive health harms, these classification systems can be updated to reflect such evidence. If specific additives are found to be harmful to health, for example, this evidence can be incorporated into existing nutrient profiling systems, such as the Health Star Rating food labelling scheme.

Accordingly, policymakers can confidently progress food policy implementation using the tools for classifying the healthiness of foods that we already have.

Unhealthy diets and obesity are among the largest contributors to poor health. We can’t let the hype and academic debate around “ultra-processed” foods delay implementation of globally recommended policies for improving population diets.

Gary Sacks, Professor of Public Health Policy, Deakin University; Kathryn Backholer, Co-Director, Global Centre for Preventive Health and Nutrition, Deakin University; Kathryn Bradbury, Senior Research Fellow in the School of Population Health, University of Auckland, Waipapa Taumata Rau, and Sally Mackay, Senior Lecturer Epidemiology and Biostatistics, University of Auckland, Waipapa Taumata Rau

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