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Giardia lamblia Annotated Bibliography
Andrew Stoltzfus
Biology and Chemistry, Liberty University
BIOL 303: Microbiology
Dr. Becker
November 11, 2024
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Giardia lamblia Annotated Bibliography
1. Adam R.D. 2021. Giardia duodenalis: biology and pathogenesis. Clinical
Microbiology Reviews 34. https://doi.org/10.1128/CMR.00024-19 (review article)
a. The review article explains the biology and infection of the parasite, G.
lamblia. The article goes through the cell biology, biosynthesis and energy
metabolism, membrane proteins, epidemiology, pathogenesis, malnutrition,
diagnosis, and treatment of G. lamblia. The main purpose of the review article
was to provide information involved in understanding G. lamblia.
b. The article discusses the immune response of the parasite. This topic is
interesting because cells shown to be involved in the immune response in
mice models correlated with the immune response in human infections. TH17
cells produce IL-17A which plays a major role in the immunity of the parasite,
G. lamblia. IL-17RA is a regulator of the immune response to Giardia. Mice
with knockout IL-17RA were infected with G. muris and the expression of
genes normally upregulated by Giardia were inhibited. CD4 response with IL-
17A was documented in infected humans. The article also explained the wide
range of symptoms associated with the infection of the parasite. I thought it
was interesting because the geographical area played a role in the severity of
the symptoms. The treatment method is also hard to administer because of the
wide range of symptoms, re-infection rates, and antibiotic resistance.
c. The article mentioned that further research on the immune response and
differences in the severity of infection will help attain appropriate therapy
strategies for treating the infection of G. lamblia.
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d. The article provided information that covered the basic biology, infection, and
treatment of the parasite. I wish the article provided more data on the
differences in infection and symptoms from a geographical point-of-view.
e. The parasite must replicate in the trophozoite form when it is adhered to the
small intestinal wall. The symptoms range from asymptomatic to severe
diarrhea, weight loss, and abdominal pain. The article concluded that the
increase in research of the immune response will aid in the treatment of the
infection.
2. Ambre, R et al. 2020. Disturbed gut microbiota and bile homeostasis in Giardia-
injected mice contributes to metabolic dysregulation and growth impairment.
Science Translational Medicine 12: 565.
https://doi.org/10.1126/scitranslmed.aay7019 (primary research)
a. Hypothesis/objective
i. The research’s objective was to understand the mechanism involved in
the reduction of growth in infants infected with Giardia lamblia.
ii. This study was selected because it provides information on the
mechanism of the parasite.
b. Key findings/results
i. The study infected infant and adult mice with trophozoites of G.
lamblia. The infant mice infected were not able to clear the parasite
even when they reached adulthood, however adult mice that were
infected with the trophozoites were resistant to infection. Reduced bile
synthesis was observed in infected mice. The enhanced bile secretion
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may be a cause for the lingering parasite infection. Bile was shown to
be a growth factor for G. lamblia. The study also concluded that the
gut microbiota was altered in infected adult animals which is
associated with malnutrition. Loss of adipose(fat) tissue was found in
the infected animals which affects the homeostasis of the animal
during starvation. The infected animals had protein deficiency and an
increase of beta-oxidation metabolites in urine samples.
ii. The results provide several metabolic activities that effect infected
animals in the mice model that mirrors the infection of the parasite in
humans.
c. Evaluation of methods and/or experimental design
i. The study infected neonatal mice with G. lamblia and identified how it
affected bile acid homeostasis, enteric microbiota, and lipid
metabolism. Giardia lamblia strain GS was used for all experiments in
the study, which accounts for majority of human cases. In vivo and
vitro experiments were conducted. The in vitro experiments were
conducted by seeding G. lamblia trophozoites in 12 well plates and
cultured under anaerobic conditions. The culture medium contained
bovine bile, mouse bile, TCA, CA, taurine, or LysoPC C16:0. PCR,
electron microscopy, flow cytometric analysis, gut microbiota
analysis, and adipose tissue imaging were used to identify the
metabolic activities of the parasite in the infected mice.
ii. The study could add nutritional and dietary factors of the mice to
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further test the relationship between infection and dietary status.
d. Significance of the key findings as a contribution to your disease topic
i. The study provided numerous information on metabolic activities
associated with G. lamblia that provides understanding on the
physiology of the parasite.
e. Future research and discussion
i. Future research could be conducted on the specific factors that alter
the enteric microbiota and dysregulated metabolism.
ii. The research supports other studies research on the delayed growth of
those infected with G. lamblia.
3. Fantinatti, M., Cascais-Figueredo, T., Austriaco-Teixeira, P., Carvalho-Costa, F., Da-
Cruz, A. 2023. Memorias Do Instituto Oswaldo Cruz 118: e230043.
https://doi.org/10.1590/0074-02760230043 (primary research)
a. Hypothesis/objective
i. The study was conducted to analyze the effect of Giardia lamblia on
the physical development of children.
ii. This research was selected because it provides data on the physical
effect of the different assemblages of G. lamblia.
b. Key finding/results
i. The children infected with the parasite, G. lamblia were shown to have
nutritional and growth deficits. Asymptomatic children were found to
carry the same malabsorptive syndrome caused by the parasite. The
infection causes changes to physiology of the small intestine by
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messing with the glucose and mineral metabolism.
ii. The study provided data on the physical and physiological effects that
G. lamblia has on children which is important for the awareness and
prevention of the parasite.
c. Evaluation of methods and/or experimental design
i. Stool samples were collected from a sample size of 220 children at a
daycare to examine for the protozoan parasite, G. lamblia. The
children were provided five meals a day by a nutritionist. The stool
samples were analyzed using the Richie method. Molecular diagnosis
and genotyping were done by extracting DNA using QIAamp DNA
stool mini kit. The local health department conducted standard
deviation scores of weights and height for age.
ii. The reverse causality could be further studied. The malnutrition and
physical development stunts may cause the increase in the infection
risk for the parasite. The research was done in a low-socioeconomic
area that may have played a role in the physical growth stunts.
d. Significance of the key findings as a contribution to your disease topic
i. The research reveals the drastic effects of the infection of Giardia
lamblia on children’s growth and physical development.
e. Future research and discussion
i. The next step of research is to look at the cellular and enzymatic
activities involved in the lack of nutritional absorption associated with
the stunted growth of the children.
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ii. The study is consistent with previous research on the physical and
nutritional effects of the parasite, Giardia lamblia.
4. Masoori, L., Khalaf, A., Ezzatkhah, F., Balaña-Fouce, R., Mahmoudvand, H. 2024.
Promising effects of 1,8 cineole to control Giardia lamblia infection: targeting the
inflammation, oxidative stress, and infectivity. Acta Tropica 255.
https://doi.org/10.1016/j.actatropica.2024.107201 (bonus)
a. Hypothesis/objective
i. The objective of the study was to understand the effects of eucalyptol
(ECT) and metronidazole (MNZ) independently and in combination on
Giardia lamblia.
ii. The article was selected because it provides therapeutic strategies for
the parasite.
b. Key findings/results
i. ECT and MNZ were shown to degrease the growth of G. lamblia in
comparison to a control group. ECT was shown to increase plasma
membrane permeability. ECT was administered to mice. 7 days later
there was a significant decrease in the G. lamblia cysts. ECT in
combination with MNZ had the greatest decrease in G. lamblia cysts
on the animal model. PCR analysis was done and revealed genes
present in infected mice, but ECT and MNZ were administered to the
infected mice the gene expression reduced. ECT was shown to have no
substantial effect on the mice’s liver and kidney function. ECT and
MNZ were concluded to contain synergistic effect on G. lamblia.
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ii. These results provide positive data on the treatment of giardiasis.
c. Evaluation of methods and/or experimental design
i. The study obtained fecal samples of individuals with giardiasis. The
samples were analyzed by light microscopy and stained with 0.1%
eosin. The trophozoites were obtained by suspending the cysts in
hydrochloric acid and then cultured. The trophozoites were treated
with ECT, MNZ, and a combination of both. SYTOX green assay was
used to analyze the effect on plasma membrane permeability. Real-
time PCR was used to analyze the effects on gene expression. 64 mice
were used as an animal model. The mice were injected with the G.
lamblia cysts orally and then treated with ECT, MNZ, and a
combination for 1 week. After the week the fecal matter was sampled
and analyzed for reduction of G. lamblia cysts.
ii. The study could have added several sets of concentrations for the
drugs to test for the minimum inhibitory concentration. The toxicity
was tested for the liver and kidney function. The study could have
included other organs in the analyzation of toxicity.
d. Significance of the key findings as a contribution to your disease topic.
i. The research provides data that is useful for the treatment of the
parasitic infection. The research is relevant to the understanding of the
growth and survival of G. lamblia.
e. Future research and discussion
i. The next step in the research would be a more detailed study on the
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concentration and dosage of the drugs as well as the degree of toxicity.
ii. The research is consistent with the use of ECT and MNZ to treat G.
lamblia.
5. Steele-Ogus, M., Obenaus, A., Sniadecki, N., Paredez, A. 2022. Disc and actin
associated protein 1 influences attachment in the intestinal parasite Giardia lamblia.
PLoS pathogens 18: e1010433. https://doi.org/10.1371/journal.ppat (bonus)
a. Hypothesis/objective
i. The study’s objective was to identify the role of GlActin and DAAP1
in the morphology and function of Giardia lamblia. The two proteins
are related to the attachment of the parasite to the small intestine of the
host.
ii. The research was selected because it provides a deep explanation of
the factors involved in host attachment of Giardia lamblia.
b. Key findings/results
i. The study used an antisense translation-blocking morpholino to block
GlActin and analyzed the attachment of Giardia. 23% of the cells
attached to the culture tube compared to 75% before the blockage of
GlActin. The study analyzed the death of the cells to note if that
played a role in the lack of attachment. The cells without GlActin
contained more dead cells than the control, but not a significant
amount. GlActin was found to be associated with ventral disc
morphology and host attachment. DAAP1 was found to play a role in
the ventral disc morphology, but lower levels of DAAP1 did not result
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in change of morphology.
ii. The results are important in understanding the infection and survival of
the parasite, Giardia lamblia.
c. Evaluation of methods and/or experimental design
i. G. lamblia strain WB was cultured, protein extracted, and then
analyzed via western blotting. Immunofluorescence microscopy was
used for imaging. Cells were treated with a control or anti-GlActin.
The cells were incubated at 37ºC on TYDK media. Each tube was
inverted six times and counted for detached cells by a MoxiZ coulter
counter. DAAP1 were treated by CRISPRi instead of the anti-GlActin.
ii. Variant surface proteins (VSPs) could be analyzed following similar
procedures to further understand the role they play in attachment.
d. Significance of the key findings as a contribution to your disease topic
i. The research provides data on the effect of specific proteins, GlActin
and DAAP1 involved in the attachment and morphology of G. lamblia.
This is important in understanding how the parasite survives and
infects its host.
e. Future research and discussion
i. The next step in research would be to conduct therapy strategies to
treat giardiasis using the knowledge of the proteins.
ii. The data is consistent with previous research on the role of GlActin in
the maintain cell structure in other organisms.
