Preventive Vaccines

Background

St. Jude Children’s Research Hospital houses an ambitious program to fight potentially fatal infections in children. The effort falls under the umbrella of the hospital’s Children’s Infectious Diseases Center (CIDC).

More than 12 million children die each year from four types of infections: respiratory viruses, tuberculosis, cholera, and acquired immune deficiency syndrome (AIDS). It is often hard to diagnose these illnesses, there are no effective vaccines for children, and there is a constant threat that antibiotic-resistant viruses and bacteria will emerge. These contagious infections can spread rapidly, and children younger than 3 are often the most vulnerable because their immune systems are still developing.

A key part of this effort is the development of preventive vaccines, which will protect children from developing these deadly infections. Vaccines are one of the greatest achievements of modern medicine. But none exist for many deadly or debilitating diseases.

A vaccine is a suspension of whole or parts of bacteria or viruses (live or inactivated) that have been engineered so that they don’t make the immunized person sick but do induce an immune response and prevent disease.

St. Jude has a complete vaccine program – from the concept and research phase, through preclinical and clinical trials, to actual vaccine production. It operates three different vaccine programs, which focus on AIDS, respiratory viruses, and bacterial infections. The hospital’s tuberculosis effort is developing an antibiotic to treat the disease. Tuberculosis infects one-third of the world's population, killing about 2.9 million people per year.

 

AIDS

AIDS (acquired immune deficiency syndrome) is a viral infection that attacks the immune system, leaving patients extremely vulnerable to deadly infections. It is caused by HIV (human immunodeficiency virus). The St. Jude AIDS vaccine is designed to trigger immune responses to multiple, differing kinds of HIV using the harmless outer coating of HIV known as the envelope. The incorporation of many envelopes is aimed at representing a cross section of virus envelopes that have emerged throughout the world during the 20-year global epidemic.

Clinical trials for the St. Jude AIDS vaccine were launched in 1997. When completed, the vaccine will be given in three parts – DNA, virus, and protein. This approach will expose individuals to many different arms of the immune response – not just a few. The AIDS vaccine is based on the smallpox vaccine that globally eradicated smallpox in humans by the late 1970s. St. Jude is using 23 different HIV envelopes each contained in a smallpox vaccine backbone. The DNA vaccine prompts the production by the body's cells of envelope proteins that then stimulate the immune system. Robert Webster, Ph.D., at St. Jude, pioneered the DNA vaccine strategy. The protein vaccine delivers a booster of purified envelope proteins.

 

Respiratory viruses

This program is developing one vaccine that will protect people from three different respiratory viruses: parainfluenza, influenza, and respiratory syncytial virus (RSV). Parainfluenza causes croup, an upper and lower respiratory infection often characterized by a spasmodic, barking cough. Each year influenza viruses cause serious, sometimes lethal, infections in humans. RSV is a lower respiratory infection and can be fatal in young children.

 

Bacterial infections

This part of the program will attack cholera and pneumococcal infections.

 

Cholera

Cholera is an infection that strikes the small bowel and is characterized by watery diarrhea, vomiting, cramps, dehydration, and collapse. It kills 2.5 million people a year worldwide and is highly lethal in young children. St. Jude researchers have developed a cholera vaccine. Clinical trials are scheduled to begin in 2003.

 

Pneumococcus

The pneumococcus bacterium is the leading cause of illness in young children. It causes many types of infections, including ear infections, pneumonia, meningitis, and sepsis. St. Jude has developed an improved pneumococcal vaccine that includes a protein that will make the vaccine broader-based and more effective in very young children.

St. Jude is also working on a Group B streptococcus (GBS) vaccine. GBS is a potentially fatal infection that strikes newborns.