NOV 02, 2015 05:04 PM PST

Deciphering Salmonella Host Specificity

WRITTEN BY: Kerry Evans
1 11 1470
What makes a strain of Salmonella infect cows, but not humans or birds?

Researchers at the University of Pennsylvania combed the genomes of 580 Salmonella strains for mutations that could determine host specificity.  The group used a technique called “genome-wide association studies” (GWASs) to identify the mutations. GWASs analyze genome sequences to identify mutations associated with specific traits (like diseases).  Often, these analyses focus on SNPs - single nucleotide polymorphisms.  SNPs are genetic mutations that change one DNA base to another - an adenine into a thymine, for example.  Many SNPs are harmless, but some result in amino acid changes.
 
Salmonella displays host specificity.

Salmonella enterica serovar Typhimurium contained a large number of SNPs within genes for surface and secreted proteins.  This particular serovar (or strain) is a common cause of food poisoning in humans. Humans contract this strain of Salmonella by eating contaminated food.  Since Salmonella is a facultative intracellular pathogen, it is able to infect cells that line the intestine, leading to symptoms of food poisoning (diarrhea, nausea, vomiting).  Salmonella prefers to live in association with its host, but is able to survive in the environment - on produce, for example - for weeks.   

According to study author Dieter Schifferli, “we saw this huge variation in proteins on the surface of bacteria or in secretions, which are really the first lines of interaction with the host … if there was so much variation, it suggests it must be linked to something important”.  

Based on their findings, the group focused their attention on the gene for the proteinaceous surface adhesin FimH.  They introduced cow and human-specific fimH mutations into E. coli and tested the bacteria’s ability to adhere to host cells.  They found that a single amino acid change in human-specific FimH caused E. coli to preferentially bind to cow cells.  In other words, this relatively small mutation was responsible for a change in host specificity.  

Schifferli now plans to determine whether there are genetic differences that determine whether Salmonella will cause mild food poisoning or more serious disease.  

Sources: Eurekalert, Salmonella.org, Wikipedia
 
About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
MAY 16, 2018
Immunology
MAY 16, 2018
Antibodies Neutralize Two Different Hemorrhagic Fever Viruses
Scientists have found evidence for potential antibody-based therapeutics to treat more than one hemorrhagic fever virus at once. From Harvard Medical Schoo
MAY 21, 2018
Cancer
MAY 21, 2018
Malarial Organism Characteristics Leads Researchers To Potential Cancer Therapeutic Target
The malarial parasite expresses a protein, VAR2CSA, that binds to chondroitin sulfate (CS) found on both placental and cancer tissues. Recombinant rVAR2 could be used to target drugs to CS.
JUN 08, 2018
Clinical & Molecular DX
JUN 08, 2018
Early Detection of Tooth Decay from Bacterial Invasion
We all get cavities, but have we ever thought much about the biology of the process? From the Akson Russian Science Communication Association, scientists i
JUN 20, 2018
Immunology
JUN 20, 2018
Immune System Accidentally Allows Meningitis Brain Infection
Several immune cells help fungi infect the brain and cause meningitis when they should be doing the exact opposite. From the University of Sydney, research
JUN 28, 2018
Videos
JUN 28, 2018
A Vaccine for Syphilis is in the Works
Now that the scientists have studied the protein and its potential, they will begin to enroll participants in a study.
AUG 06, 2018
Immunology
AUG 06, 2018
Maternal Dengue Immunity Protects Against Infant Zika Infection
Maternal Dengue immunity produces CD8+ T cells that protect against fetal Zika infection preventing zika-related malformations.
Loading Comments...