Topic: Biology

Scientists discovered why bird flu virus behaves differently in dairy cows. They found that the virus targets a specific type of sugar-based molecule in cow udder tissue, causing severe infections.

When H5N1 bird flu started infecting US dairy cattle in early 2024, veterinarians were puzzled. The virus was difficult to identify because it behaved very differently in cows than in other mammals. Instead of primarily infecting the lungs, H5N1 caused severe infections in cow udders while leaving the respiratory system largely unaffected.

Researchers at the University of Pittsburgh School of Public Health uncovered the biological reason behind this unusual pattern. Their findings, published in Science Advances, provide the first detailed explanation for why bird flu took such an unexpected form in cattle.

The outbreak began in dairy herds in Texas, where animals developed severe cases of necrotizing mastitis, a painful inflammatory disease that damages tissue in the mammary glands. Veterinarians were initially looking for bacterial pathogens but found no signs of infection. It was only later that bird flu was identified as the culprit.

The research team combined multiple techniques to examine how H5N1 interacts with different tissues. Their analysis showed that not all glycan receptors function the same way when it comes to bird flu infection. The virus binds only to a specific subtype of sugar-based molecules known as N-linked sialic acid receptors, which are found throughout cow udder tissue but nearly absent in airway tissue.

This discovery helps explain why H5N1 caused severe mastitis rather than respiratory illness in dairy cattle.

Why It Matters

Understanding how bird flu behaves in different animals can help us prepare for future outbreaks and prevent the spread of disease. This research has important implications for public health, especially in countries where dairy farming is common.

Key Facts

• H5N1 bird flu started infecting US dairy cattle in early 2024
• The virus caused severe infections in cow udders rather than lungs
• Researchers at the University of Pittsburgh School of Public Health discovered why H5N1 behaves differently in cows
• The virus binds to a specific type of sugar-based molecule called N-linked sialic acid receptors

Key Terms

Glycan

A type of sugar-based molecule found on cell surfaces

Implications

Understanding how bird flu behaves in different animals can help us prepare for future outbreaks and prevent the spread of disease. This research has important implications for public health, especially in countries where dairy farming is common.