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Giardia duodenalis

Table of Contents
  1. General Information
    1. NCBI Taxonomy ID
    2. Disease
    3. Introduction
    4. Microbial Pathogenesis
    5. Host Ranges and Animal Models
    6. Host Protective Immunity
  2. Vaccine Related Pathogen Genes
    1. CWP2 (Protective antigen)
  3. Vaccine Information
    1. G. duodenalis DNA vaccine encoding CWP2
    2. Giardia Lamblia Killed Protozoa Vaccine (USDA: 18G5.00)
    3. Giardiavax
  4. References
I. General Information
1. NCBI Taxonomy ID:
5741
2. Disease:
Giardiasis (Beaver fever)
3. Introduction
Giardia lamblia (synonymous with Lamblia intestinalis and Giardia duodenalis) is a flagellated protozoan parasite that colonises and reproduces in the small intestine, causing giardiasis. The giardia parasite attaches to the epithelium by a ventral adhesive disc, and reproduces via binary fission[1]. Giardiasis does not spread via the bloodstream, nor does it spread to other parts of the gastro-intestinal tract, but remains confined to the lumen of the small intestine. Giardia trophozoites absorb their nutrients from the lumen of the small intestine, and are anaerobes. If the organism is split and stained, it has a very characteristic pattern that resembles a familiar "smiley face" symbol.

Colonization of the gut results in inflammation and villous atrophy, reducing the gut's absorptive capability. In humans, infection is symptomatic only about 50% of the time, and protocol for treating asymptomatic individuals is controversial. Symptoms of infection include (in order of frequency) diarrhea, malaise, excessive gas (often flatulence or a foul or sulphuric-tasting belch, which has been known to be so nauseating in taste that it can cause the infected person to vomit), steatorrhoea (pale, foul smelling, greasy stools), epigastric pain, bloating, nausea, diminished interest in food, possible (but rare) vomiting which is often violent, and weight loss (Wiki: Giardia lamblia).
4. Microbial Pathogenesis
Infection is initiated by the ingestion of live infective cysts from contaminated water or food or through person to person transmission. When cysts reach the stomach, gastric acidity and intestinal proteases promote excystation. Newly emerging excyzoites immediately divide into two trophozoites that migrate to the duodenum and adhere to the intestinal mucosa by virtue of their ventral discs. Giardia trophozoites reproduce asexually by binary fission and gradually populate the host's intestinal lumen. Under the influence of bile salts, a number of trophozoites undergo differentiation resulting in cyst formation. Encystation of trophozoites represents an important step in the completion of the parasite's life cycle since it leads to the formation of the cyst structure, necessary for the transmission of the parasite from host to host. Infected humans are estimated to excrete between 150 and 20,000 cysts/g feces daily, whereas infected cattle can excrete up to 106 Giardia cysts/g feces. The quadrinucleate cysts are resistant to the external environment and can remain viable from days to months if kept wet (Abdul-Wahid and Faubert, 2007).
5. Host Ranges and Animal Models
Giardia infects humans, but is also one of the most common parasites infecting cats, dogs and birds. Mammalian hosts also include cows, beavers, deer, and sheep (Wiki: Giardia lamblia).
6. Host Protective Immunity
Humoral immunity is believed to be important in elimination of Giardia trophozoites from the host intestine. Raised levels of serum and mucosal antibodies are found in experimentally infected animals and infected humans during the elimination phase of the Giardia parasite, and the host produces specific serum and mucosal antibodies directed against both surface and cytosolic antigens (Olson et al., 2000).
1. CWP2
  • Gene Name : CWP2
  • Sequence Strain (Species/Organism) : Giardia lamblia ATCC 50803
  • VO ID : VO_0011080
  • NCBI Gene ID : 5703171
  • NCBI Protein GI : 159120052
  • Locus Tag : GL50803_5435
  • Genbank Accession : AACB02000001
  • Protein Accession : XP_001710242
  • Taxonomy ID : 50803
  • Gene Starting Position : 1061836
  • Gene Ending Position : 1062924
  • Gene Strand (Orientation) : -
  • Protein pI : 8.13
  • Protein Weight : 37700.21
  • Protein Length : 362
  • DNA Sequence : Show Sequence
    >ref|NW_002477099.1|:1061836-1062924 Giardia lamblia ATCC 50803 SC_592, whole genome shotgun sequence
    TTCACCTTCTGCGGACAATAGGCTTGTTCGTGCTGCGAGGCAGAGCTCTCACGGGTGCACGCTTCGATTG
    GGTCGGCTTGGTGATCGCACGAGCGGTGGGGCGGGCTACAGCAGAGCGGCTAGCATTGCCAGTCACAGAG
    CTCCTCGATTGGACCGTCTTCTTGGGAGCCGTCCTGGAGCGGGACGTTGAGGCCGTCTTGCTAGATGACC
    TAACCACTGTCCTGAGCGGTGTTTGGCTGCGGCTGTTTGGCATGTTGCATTTCCTCTGCGCATTGTGTGC
    ACTGTTGTGCATGTTGCTCTTGGCCTTGCCACAGTTGGAGGCGCTACGAGCGTTGCAGCTTGTCTTTCGT
    CCCGACGCATTGCGGACTACTGTCTGCCTGTAGTACGTGCATCCATCTCTCTCGAGAGTTGTGGGGCAGT
    TTGTCGGCGGGAGAGCAGTGCAGTAATCGCAGTCTGTTGTTCCACAGAGGTAGATTCCGGTGTAGGTGTC
    AGGCGCAGCTGTGCAAACGAGATCGGTGTTGCACTGGACATGAATCTCCATCATGTAAGGCAGGTCGAAG
    AGATCTGCCGGAACGTCGCCAGTCAGCTCGTTGCAGTCAAGGTGGAGCTCCTTGAGGAATTGGAGTTCGT
    TGACGCAGGTGGGGATGGGACCAGTGAGAGCATTAATACTCATGTACCAAAACATCATGTGGGTTAAATC
    ACAGATGCACTCGGGAATGTCACCCGTCAGCCCAGCGTTGTTAATTTGCAGGTACTGCATTGAGGTGAGG
    GCACAAAGATCCGTCGGGATCGGGCCCGCAAGGTCATTATTATTAAGGTACAGCGACCTCAAAAGTGGGA
    AGCAGCCTATGTCGGCAGGGAGGGCACCAGTGAGCCCCATGTCAGAGAGGTCGATCCCAATAACGTTATT
    GTTAGAGTCGCATGTGATGCCGGTCCAGCTACAGTAAGACACGTCGGGCGTAAGCCAGTTATTCGACTTC
    CAATTAGCACCATCCAGGGCATCGTACAAATTGGTCAGGGCCTCCTCCTCGGTGGCAGGGCAAGCGGCGC
    GAGCAAGACCAAGAAGTCCTAGAACAAGGGCTGCGATCA
  • Protein Sequence : Show Sequence
    >gi|159120052|ref|XP_001710242.1| Cyst wall protein 2 [Giardia lamblia ATCC 50803]
    MIAALVLGLLGLARAACPATEEEALTNLYDALDGANWKSNNWLTPDVSYCSWTGITCDSNNNVIGIDLSD
    MGLTGALPADIGCFPLLRSLYLNNNDLAGPIPTDLCALTSMQYLQINNAGLTGDIPECICDLTHMMFWYM
    SINALTGPIPTCVNELQFLKELHLDCNELTGDVPADLFDLPYMMEIHVQCNTDLVCTAAPDTYTGIYLCG
    TTDCDYCTALPPTNCPTTLERDGCTYYRQTVVRNASGRKTSCNARSASNCGKAKSNMHNSAHNAQRKCNM
    PNSRSQTPLRTVVRSSSKTASTSRSRTAPKKTVQSRSSVTGNASRSAVARPTARAITKPTQSKRAPVRAL
    PRSTNKPIVRRR
  • Molecule Role : Protective antigen
  • Molecule Role Annotation : The gene encoding the full length cyst wall protein-2 (CWP2) from Giardia lamblia was subcloned into the pCDNA3 mammalian expression vector and stably introduced into S. typhimurium STM1. Challenge infection with live Giardia muris cysts revealed that mice receiving the CWP2-encoding DNA vaccine were able to reduce cyst shedding by approximately 60% compared to control mice (Abdul-Wahid and Faubert, 2007).
  • Related Vaccine(s): G. duodenalis DNA vaccine encoding CWP2
III. Vaccine Information
1. G. duodenalis DNA vaccine encoding CWP2
a. Vaccine Ontology ID:
VO_0011550
b. Type:
DNA vaccine
c. Status:
Research
d. Antigen
G. duodenalis cyst wall protein-2 (CWP2)
e. Gene Engineering of CWP2
  • Type: DNA vaccine construction
  • Description: The cwp2 open reading frame was amplified by PCR and sub-cloned between the EcoRI and NotI restriction sites in the multiple cloning site of pCDNA3. Both the empty and recombinant pCDNA3 plasmids were purified from transformed Escherichia coli DH5α using the Qiafilter plasmid purification kit from Qiagen (Ont., Canada) according to the manufacturer's instructions. The plasmids were transformed into the SL1655 restriction modified strain of S. typhimurium (kindly provided by Dr. Ken Sanderson; Salmonella genetic stock center, Calgary, Canada) to stabilize the plasmids in STM1, and then purified and re-introduced into the STM1 strain of S. typhimurium (kindly provided by Dr. Peter Smooker; RMIT University, Melbourne, Australia). All bacterial cultures were maintained in Lauria Bertani (LB) culture medium supplemented with ampicillin (150 μg per mL) (Abdul-Wahid and Faubert, 2007).
  • Detailed Gene Information: Click here.
f. Vector:
pCDNA3 mammalian expression vector
g. Immunization Route
Oral
h. Mouse Response
  • Host Strain: BALB/c
  • Vaccination Protocol: For oral DNA immunization, mid-log phase Salmonellae were collected by centrifugation and re-suspended in ice cold PBS. Mice were orally immunized with 300 μL containing 109 CFUs by gavage using a blunt-ended probe. The animals were immunized every 2 weeks for a total of three immunizations. This dose and regimen were used as they were found to stimulate the highest level of CWP2-specific immune response without causing any toxic side effects to the mice (Abdul-Wahid and Faubert, 2007).
  • Challenge Protocol: DNA immunized and control mice (n = 12 mice per group) were challenged with 105 G. muris cysts a week following the last immunization (Abdul-Wahid and Faubert, 2007).
  • Efficacy: The gene encoding the full length cyst wall protein-2 (CWP2) from Giardia lamblia was subcloned into the pCDNA3 mammalian expression vector and stably introduced into S. typhimurium STM1. Challenge infection with live Giardia muris cysts revealed that mice receiving the CWP2-encoding DNA vaccine were able to reduce cyst shedding by approximately 60% compared to control mice (Abdul-Wahid and Faubert, 2007).
2. Giardia Lamblia Killed Protozoa Vaccine (USDA: 18G5.00)
a. Manufacturer:
Wyeth
b. Vaccine Ontology ID:
VO_0001750
c. Type:
Inactivated or "killed" vaccine
d. Status:
Licensed
e. Location Licensed:
USA
f. Host Species for Licensed Use:
Gray wolf
3. Giardiavax
a. Tradename:
Giardiavax
b. Manufacturer:
Fort Dodge
c. Vaccine Ontology ID:
VO_0001008
d. Type:
Subunit vaccine
e. Status:
Licensed
f. Host Species for Licensed Use:
Dog
g. Immunization Route
Intramuscular injection (i.m.)
h. Description
Cultured trophozoites, reduces disease and cyst shedding(Olson et al., 2000)
IV. References
1. Abdul-Wahid and Faubert, 2007: Abdul-Wahid A, Faubert G. Mucosal delivery of a transmission-blocking DNA vaccine encoding Giardia lamblia CWP2 by Salmonella typhimurium bactofection vehicle. Vaccine. 2007; 25(50); 8372-8383. [PubMed: 17996337].
2. Lee et al., 2009: Lee P, Abdul-Wahid A, Faubert GM. Comparison of the local immune response against Giardia lamblia cyst wall protein 2 induced by recombinant Lactococcus lactis and Streptococcus gordonii. Microbes and infection / Institut Pasteur. 2009; 11(1); 20-28. [PubMed: 18992359].
3. Olson et al., 2000: Olson ME, Ceri H, Morck DW. Giardia vaccination. Parasitology today (Personal ed.). 2000; 16(5); 213-217. [PubMed: 10782082].
4. Wiki: Giardia lamblia: Giardia lamblia [http://en.wikipedia.org/wiki/Giardia_duodenalis]