por: valentina feris y juliana dominguez salazar

1. By: Valentina Feris and Juliana Dominguez Salazar
III Semester
Universidad Pontificia Bolivariana.

2. INTRODUCTION
LISTERIA MONOCYTOGENES
● Family: Listeriaceae (listeria)
● Type: Intracelular Gram +, facultative and
anaerobic bacillus
● Diseases: Threatening infections like
sepsis and meningitis.

3. Virulence factor and inflammation
Virulence factors secreted by L. monocytogenes:
● Listeriolysin O (LLO)
● The pore-forming toxin
LLO can induce a variety of apoptosis and cytotoxicity
pathways, which suggests that LLO is an important and effective
drug target for the treatment of L. monocytogenes infection.
Effective alleviation of the inflammatory response might be an
important strategy for the treatment of L. monocytogenes
infection.
Morin is a potential drug precursor, particularly in the fight
against L. monocytogenes infection.
L monocytogenes infection
Inflammatory reactions
Encephalitis,
osteomyelitis
and peritonitis
Activates the
assembly of AIM2,
NLRC4 and NLRP3
inflammasomes
● Caspase 1
● IL-1β, IL-6, and
TNF-α

4. OBJECTIVE:
Determinate if Morin inhibits Listeria monocytogenes
virulence in vivo and in vitro by targeting listeriolysin O and
inflammation

5. METHODS
Minimum inhibitory concentration (MIC):
In this study, the growth of L. monocytogenes in the presence of different concentrations of morin was evaluated
through MIC. MIC assays determine the lowest concentration of morin that prevents visible growth of L.
monocytogenes. To do an MIC, one inoculates the test substance with an invisible but high number of
microorganisms, then observes the mixture of microorganisms and test substance to see if it changes from clear to
cloudy. If it turns cloudy, that means microorganisms have grown to high levels, and the test substance is not
inhibitory to them at that particular dilution.

6. Hemolysis assay
In the hemolysis assay, human red blood cells and test materials are co-incubated in buffers at defined pHs
that mimic extracellular, early endosomal, and late endo-lysosomal environments. Following a centrifugation
step to pellet intact red blood cells, the amount of hemoglobin released into the medium is
spectrophotometrically measured (405 nm for best dynamic range). The percent red blood cell disruption is
then quantified relative to positive control samples lysed with a detergent. In this model system the
erythrocyte membrane serves as a surrogate for the lipid bilayer membrane that enclose endo-lysosomal
vesicles. The desired result is negligible hemolysis at physiologic pH (7.4) and robust hemolysis in the endo-
lysosomal pH range from approximately pH 5-6.8.

7. WESTERN BLOTTING:
In this article is to
analyze how Fisetin
inhibits Listeria
monocytogenes
virulence by
interfering with the
oligomerization of
listeriolysin

8. Enzyme-Linked ImmunoSorbent Assay (ELISA)

9. RESULTS
Morin has no influence on L. monocytogenes growth
Fig 1d. The expression of LLO in L. monocytogenes cultures treated with different concentrations of morin was
assessed by Western blotting using a specific antibody against LLO.
They tested the expression of LLO in the supernatant of bacterial
cultures treated with different concentrations of morin and they
found that morin treatment did not interfere with the secretion of
LLO.
In summary, morin does not affect the growth of Listeria, which
suggests that the use of morin for the treatment of Listeria infection
would not impose too much pressure on the survival of the bacteria.

10. Morin protects mice infected with L. monocytogenes and reduces the
bacterial burden and inflammation in vivo

11. RESULTS: WESTERN BLOTTING
- Inhibitory effects of morine on
oligomer formation and hemolytic
activity of LLO.
- The purified LLO proteins were treated
with morin, and inhibition of LLO
oligomerization by morine was
evaluated by this method

12. ELISA

13. DISCUSSION
AUTHOR AUTHOR QUOTE´S
Lomonaco S et al “L. monocytogenes is an important
opportunistic food
borne bacterium of both humans and
animals and is the etiological agent of
listeriosis and a series of fatal infections.”
Camargo AC et al “However, an increasing number of
Listeria strains that can survive antibiotic
treatment are being discovered clinically
at higher frequencies, and the problem of
Listeria resistance is becoming more
serious.”
Roulo RM et al “which suggests that LLO deletion could
be regarded as an important and effective
target in the therapy of Listeria infections.
In addition, the severe inflammatory
response caused by Listeria infection also
causes harm to the infected host and
particularly induces a risk for abortion in
pregnant women.”

14. CONCLUSIONS
1. Various techniques have been developed for molecular biology, like the ones we saw
in this article for example: ELISA, WesternBlotting, Hemolysis Assay and MIC. All of
these different types of techniques led us to conclude morin does not affect the
growth of Listeria, but it helps to reduce The inflammation that it caused.
2. The application of principles of molecular biology in medicine focuses primarily on
treating diseases. Advances in the fields of molecular biology and genetic engineering
are beginning to directly impact in disease prevention, diagnosis, and treatment.
3. DNA can now be isolated, purified, amplified, and sequenced routinely easily. With
these advances, doctors may soon be able to identify patients with diseases, or
quickly identify a specific virus or bacteria.

15. MAPA CONCEPTUAL VALENTINA FERIS
Realicé el mapa conceptual en Lucidchart, a continuación dejo el link respectivo:
https://app.lucidchart.com/invitations/accept/fd92be08-8647-4353-8b0c-e1e2bb4bab45
NOTA: el mapa
conceptual no queda
muy nítido y no se
alcanzan a ver unas
noticas adicionales que
valentina puso. Es mejor
verlo desde la página.

16. MAPA CONCEPTUAL JULIANA DOMINGUEZ S.
NOTA: se ve mejor al poner la diapositiva en modo presentación