Multivalent vaccine protection from Staphylococcus aureus infection

Abstract

Vaccine formulations effective against Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus (MRSA) are disclosed, as well as methods of using the vaccine formulations in the treatment and prevention of Staphylococcus aureus infections in a subject.

Description

STATEMENT OF GOVERNMENTAL INTEREST[0001]This invention was made with government support under Grant Number AI069568 awarded by the National Institutes of Health. The government has certain rights in the invention.BACKGROUND[0002]1. Field of the Invention[0003]The present invention relates to multivalent vaccine formulations effective against Staphylococcus aureus, including both biofilm and planktonic types of bacterial infections, and to methods of using the formulations in the treatment and prevention of S. aureus infections in subjects.[0004]2. Related Art[0005]One of the most common and costly problems for the U.S. healthcare system is nosocomial infections (26), with S. aureus being the second-leading cause of such infections (4). Methicillin-resistant S. aureus (MRSA) is responsible for 40-60% of all nosocomially-acquired S. aureus infections, and these resistant strains are now considered to be endemic in the hospital setting (36). Community-associated S. aureus strains may a...

AI Technical Summary

Benefits of technology

The present invention is about creating vaccine formulations that can help prevent infections caused by a type of bacteria called S. aureus. These vaccines could be particularly useful for people who have a higher risk of developing these infections. By using an anti-biofilm vaccine, it is possible to stop or cure these infections without needing to have surgery. This would mean that people who have been infected with S. aureus could be saved from chronic disease and avoidable complications.

Problems solved by technology

Treating prosthetic implant infections is a complicated process, and a number of staphylococcal defense mechanisms may be responsible for this difficulty as well as the capacity of S. aureus to evade clearance by the host immune response.

Biofilm formation by S. aureus during prosthetic implant infection makes eradication of this bacteria extremely difficult, due in part to the dramatically increased resistance of bacteria in a biofilm to host defenses (21) and to antibiotics (46, 51), compared to their planktonic counterparts.

Most vaccines evaluated to date do not account for biological redundancy of S. aureus virulence factors, differential protein expression during different modes of growth (exponential growth versus stationary) or type of infection (planktonic versus biofilm), and the lack of antigen conservation amongst relevant clinical isolates.

The efficacy of the StaphVAX vaccine would, therefore, be limited to planktonic-type infections and ineffective at targeting the humoral response to a S. aureus biofilm.

One deficiency of these approaches was relying on a monovalent vaccine to promote protection against the pathogen. S. aureus has nearly 70 virulence factors and functional redundancy amongst these factors may abrogate the effect of neutralizing one factor.

Efficacy of a monovalent vaccine can also be compromised by differential expression of the targeted protein during the course of infection.

Hence, vaccines designed to target a MSCRAMM will be ineffective at clearance after the bacteria transition into the biofilm phenotype.

Evaluation of the MSCRAMM FnBP vaccine demonstrated it provided partial protection against S. aureus in a murine model of sepsis, but the study failed to enumerate bacteria in the blood and / or kidneys to verify bacterial clearance.

Overall, the multivalent vaccine had limited efficacy, providing complete protection against only two of five clinical S. aureus isolates tested (61).

In addition, comparative analysis of multiple S. aureus genomes found a lack of conservation amongst some surface proteins, including SdrD and SdrE (39), which indicates the limited efficacy of the IsdA / IsdB / SdrD / SdrE vaccine formulation may extend beyond the clinical isolates tested by Stranger-Jones.

While the efficacy of the PNAG vaccine against S. aureus biofilms requires further evaluation, the dispensability of the icaABDC locus in some S. aureus strains isolated from clinical infections suggests that the PNAG vaccine would provide limited protection against S. aureus biofilm infections.

Emphasis on BALB / c experimental models to evaluate S. aureus vaccines may yield insight about efficacy against acute or planktonic infections, but these models will be poor evaluators of chronic, biofilm infections and do not represent the immune response bias in humans.

Staphylococcus aureus has re-emerged as a major human pathogen and there are presently no vaccines that afford consistent, long-term protection against S. aureus infections.

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