# How Vaccines Protect Pigs from Respiratory Bacteria

> A 1999 patent describing a vaccine for swine that uses specific bacterial proteins to trigger an immune response against the lung disease caused by Actinobacillus pleuropneumoniae.

- **Patent:** US 5876725
- **Original title:** Actinobacillus pleuropneumoniae transferrin binding protein vaccines and uses thereof
- **Owner:** University of Saskatchewan
- **Granted:** 1999
- **Status:** Public domain (expired)
- **Times cited:** 3
- **Field:** biotech, pharmaceutical

## What it does

The patent details a vaccine composition designed to prevent pneumonia in pigs caused by the bacterium Actinobacillus pleuropneumoniae. It works by using specific transferrin binding proteins—molecules the bacteria use to steal iron from the host—as antigens to train the pig's immune system. By introducing these proteins, the vaccine helps the animal recognize and fight off the infection before it causes severe lung damage. The claims also cover the use of cytolysins, which are toxins produced by the bacteria, to further strengthen the immune response.

## What it does NOT cover

- Does not cover vaccines for humans or other species besides swine
- Does not cover methods for treating respiratory infections caused by viruses
- Does not cover generic iron-binding proteins from bacteria other than A. pleuropneumoniae
- Does not cover diagnostic kits or methods for detecting the bacteria in the environment

## The clever bit

The researchers targeted the bacteria's iron-acquisition system. By blocking the protein the bacteria use to steal iron, they essentially starve the pathogen while simultaneously marking it for destruction by the host's immune system.

## Real-world examples

1. Porcine respiratory disease vaccines
2. Bacterial subunit vaccines for livestock

## Why it matters

Actinobacillus pleuropneumoniae is a major economic burden for the global pork industry, causing high mortality rates and significant losses. This patent provided a molecular blueprint for creating subunit vaccines, which are safer and more precise than older methods using whole, killed bacteria.

## Frequently asked questions

### What does How Vaccines Protect Pigs from Respiratory Bacteria cover?

A 1999 patent describing a vaccine for swine that uses specific bacterial proteins to trigger an immune response against the lung disease caused by Actinobacillus pleuropneumoniae.

### Who owns patent US 5876725?

University of Saskatchewan owns this patent, granted in 1999.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 5876725 cited by?

This patent has been cited by 3 later patents that build on its ideas.

### What problem does this patent solve?

Actinobacillus pleuropneumoniae is a major economic burden for the global pork industry, causing high mortality rates and significant losses. This patent provided a molecular blueprint for creating subunit vaccines, which are safer and more precise than older methods using whole, killed bacteria.

### What does this patent NOT cover?

Does not cover vaccines for humans or other species besides swine

**Full plain-English explainer:** https://patentbrief.org/patent/us/5876725/synagis-palivizumab

**Original patent:** https://patents.google.com/patent/US5876725

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._