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What Does the Flu Look Like Under a Microscope? Facts & FAQ

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female scientist using fluorescent microscope
Image Credit: Matej Kastelic, Shutterstock

Everyone gets the flu now and then, but have you ever wondered what it looks like? Of course, we can’t see what the common flu looks like from our naked eye. After all, it’s just bacteria. Luckily, the electron microscope is the most efficient tool to look at bacteria closely.

Up close, the flu has a strange appearance, which is hard to understand unless you study each component separately. So, if you’re wondering what the flu looks like under a microscope, you’re at the right place.

Keep reading to learn about the microscopic appearance of the influenza virus and what each element means.

magnifying glass 2 divider What Is the Flu?

The influenza virus is a common and contagious illness that infects the throat, lungs, and nose. Mostly, this illness is mild, resulting in symptoms such as coughing and sneezing or a blocked nose. However, the flu can even lead to death in the worst-case scenario.

An annual flu vaccine can prevent this illness, which usually comes on without warning. Some other flu symptoms include a runny nose, sore throat, fever, headache, fatigue, or body aches. However, it’s unnecessary for everyone with the flu to have a fever.

The flu is most commonly spread due to the tiny droplets when infected people sneeze or cough around others. It’s worth noting that 9% of the US population gets the flu every season, with children and those 65+ years old being the most vulnerable.

slide under a fluorescent microscope
Photo Credit: Pan Xunbin, Shutterstock

What Does the Flu Look Like Under a Microscope?

An influenza virus particle is a virion consisting of an outer protein shell containing an inner nucleic acid core. In most cases, this inner core holds eight single-stranded RNA segments. The structure of the influenza virus is spherical, with antigens attached to it.

Part of the Orthomyxoviridae family, each virion has a diameter of approximately 80–120 nanometers. In addition, every particle holds hemagglutinin and neuraminidase antigens. These substances produce antibodies, specifying the virus’ strain.

There are three influenza viruses: A, B, and C. Influenza A is the only type that infects animals like birds and pigs. However, this flu is more dangerous once it returns to humans, as it changes within the animal’s body.

The Appearance of the Flu

In a 1994 study, scientists observed a frozen, vitrified aqueous influenza A virus suspension. They utilized a high-resolution electron microscope to study the flu. The microscopic image of the influenza particles showed small groups of spherical particles.

They discovered that an outer protein shell protected these groups. Its well-organized interior held somewhat disorganized, larger spheres and some thread-like ones. Phospholipid bilayers enveloped most of the larger particles, which did not have much viral activity.

Meanwhile, the smaller and thread-like particles were enveloped in a thin outer lipid monolayer. These particles had the most viral activity. The final outer protein shell is 7.2 nanometers thick. These structural differences were proven with the help of densitometric traces in microscopic images of the influenza virus.

The flu looks like a spherical pincushion in a thick envelope with thin, small spikes. The spikes are indicators of hemagglutinin and neuraminidase activity. When studied under an electron microscope, the image displayed two types of spikes, each with its function.

The spikes are mushroom-shaped and rod-shaped. Since their differences are hard to find, scientists separated them with a detergent disruption. As a result, they found the lipid envelope embedded with a hydrophobic portion.

Once the detergent is removed, these portions aggregate together and form cartwheel and rosette shapes. Microscopic images display these spikes in unequal portions. The hemagglutinin is typically five times more than the neuraminidase antigens.

Close up slide under a fluorescent microscope
Photo Credit: Anamaria Mejia, Shutterstock

How to Capture Clear Images of the Flu

Of course, you can’t know what the flu looks like with your naked eye. You’ll need to use specialized equipment to get a clear image of the influenza virus. Most importantly, you’ll need an electron microscope.

Electron microscopy has proven to be the most efficient way to study viruses such as the flu. Scientists utilize different sample preparation techniques to uncover different results about the virus’ nature.

For example, a negative stain helps quickly prepare an individually growing virus for imaging. On the other hand, a thin section helps capture a cross-section view inside the particle. This technique also details the virus’ original growth in the cell.

Scientists then utilize this information to determine the nature and type of virus. Then, they work with pathologists to confirm the virus’ identity. The pathologists may perform certain tests that contradict the initial test results.

Electron Microscopy for the Flu

Some consider electron microscopy an old technique, but it remains effective in most aspects. For example, there’s no better equipment than the electron microscope for viral ultrastructure and diagnoses.

It especially helps with surveying and analyzing emerging and contagious diseases. Scientists utilize cryo-electron microscopy, electron tomography, and immunoelectron microscopy. These techniques determine the placement of viral structural components and how they attach to cells.

Electron microscopy also details the components’ association with cellular machinery. This way, scientists can finalize the treatments for viral illnesses such as the flu.

It’s no doubt that electron microscopy has made significant contributions to the study of the influenza virus. It is the only microscope that can develop clear flu images for scientists to analyze.

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Final Thoughts

Humans and animals of all ages are vulnerable to the flu, but the illness can be severe for seniors, children, and certain animals. Electron microscopy has helped expedite the research on this virus. Now, it’s much easier to prevent the worst-case scenario.

Under the microscope, the flu appears strange, and the movements are unexpected. However, with clearer images of the viral structure of the flu, scientists can generate more efficient results for its prevention.

Featured Image Credit: Matej Kastelic, Shutterstock

About the Author Jeff Weishaupt

Jeff is a tech professional by day, writer, and amateur photographer by night. He's had the privilege of leading software teams for startups to the Fortune 100 over the past two decades. He currently works in the data privacy space. Jeff's amateur photography interests started in 2008 when he got his first DSLR camera, the Canon Rebel. Since then, he's taken tens of thousands of photos. His favorite handheld camera these days is his Google Pixel 6 XL. He loves taking photos of nature and his kids. In 2016, he bought his first drone, the Mavic Pro. Taking photos from the air is an amazing perspective, and he loves to take his drone while traveling.