Complement inhibitors from scabies mites promote streptococcal growth - A novel mechanism in infected epidermis?

Mika, Angela, Reynolds, Simone L., Pickering, Darren, McMillan, David, Sriprakash, Kadaba S., Kemp, David J. and Fischer, Katja (2012) Complement inhibitors from scabies mites promote streptococcal growth - A novel mechanism in infected epidermis?. Plos Neglected Tropical Diseases, 6 7: e1563.1-e1563.7. doi:10.1371/journal.pntd.0001563

Author Mika, Angela
Reynolds, Simone L.
Pickering, Darren
McMillan, David
Sriprakash, Kadaba S.
Kemp, David J.
Fischer, Katja
Title Complement inhibitors from scabies mites promote streptococcal growth - A novel mechanism in infected epidermis?
Journal name Plos Neglected Tropical Diseases   Check publisher's open access policy
ISSN 1935-2735
Publication date 2012-07
Sub-type Article (original research)
DOI 10.1371/journal.pntd.0001563
Open Access Status DOI
Volume 6
Issue 7
Start page e1563.1
End page e1563.7
Total pages 7
Place of publication San Francisco, CA, United States
Publisher Public Library of Science
Collection year 2013
Language eng
Formatted abstract
Background: Scabies is highly prevalent in socially disadvantaged communities such as indigenous populations and in
developing countries. Generalized itching causes discomfort to the patient; however, serious complications can occur as a
result of secondary bacterial pyoderma, commonly caused by Streptococcus pyogenes (GAS) or Staphylococcus aureus. In the
tropics, skin damage due to scabies mite infestations has been postulated to be an important link in the pathogenesis of
disease associated with acute rheumatic fever and heart disease, poststreptococcal glomerulonephritis and systemic sepsis.
Treatment of scabies decreases the prevalence of infections by bacteria. This study aims to identify the molecular
mechanisms underlying the link between scabies and GAS infections.
Methodology/Principal Findings: GAS bacteria were pre-incubated with blood containing active complement, phagocytes
and antibodies against the bacteria, and subsequently tested for viability by plate counts. Initial experiments were done
with serum from an individual previously exposed to GAS with naturally acquired anti-GAS antibodies. The protocol was
optimized for large-scale testing of low-opsonic whole blood from non-exposed human donors by supplementing with a
standard dose of heat inactivated human sera previously exposed to GAS. This allowed an extension of the dataset to two
additional donors and four proteins tested at a range of concentrations. Shown first is the effect of scabies mite
complement inhibitors on human complement using ELISA-based complement activation assays. Six purified recombinant
mite proteins tested at a concentration of 50 mg/ml blocked all three complement activation pathways. Further we
demonstrate in human whole blood assays that each of four scabies mite complement inhibitors tested increased GAS
survival rates by 2–15 fold.
Conclusions/Significance: We propose that local complement inhibition plays an important role in the development of
pyoderma in scabies infested skin. This molecular link between scabies and bacterial infections may provide new avenues to
develop alternative treatment options against this neglected disease.
Keyword Serine-protease paralogues
Innate immunity
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Veterinary Science Publications
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