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The article presents the current knowledge on the proteines under question. The first analysed E-S products released by G. duodenalis was a polydisperse hydrophobic complex (16.5-225 kDa), protease VI sensitive, chloroform-methanol insoluble. Based on inhibition studies cysteine protease and metalloprotease were detected in the complex. The further analysis revealed that a 58 kDa heat stable as wall as protease sensitive glycoprotein secreted by G. duodenalis trophozoites is highly immunogenic for the hosts. Before encystation, G. duodenalis trophozoites secrete leucine-rich cyst wall proteins: CWP1, CWP2 and CWP3. Steady-state levels of CWPs gene transcripts are low in non-encysting trophozoites but increase more than 100-fold during encystation. Another protein, which expression also increases during encystation is gGSP (Giardia Granule-Specific Protein). The protein possesses typical strucutre of calcium-binding proteins. Inhibition of gGSP expression abolishes cyst wall formation, suggesting that this protein regulates Ca²⁺-dependent degranulation of encystation-specific secretory vesicles (ESVs ) during cyst wall formation.
Giardia duodenalis is an ubiquitous flagellate that infects humans and many species of animals. This species exhibits great biotypic and genetic diversity. In the present study, we established short- and long-term in vitro cultures of G. duodenalis trophozoites originating from red deer and Thomson’s gazelle (artiodactyls) and genetically characterised the isolates by their glutamate dehydrogenase and triose phosphate isomerase gene sequences. The G. duodenalis isolates from red deer and the gazelle represented assemblages A (AIII sub-assemblage) and B. In conclusion, G. duodenalis assemblages and sub-assemblages can be associated with differences in growth rate in vitro cultures.
In this paper we report the occurrence of zoonotic species of Cryptosporidium (C. ubiquitum and C. parvum subtype IIaA15G2R1) and the host-specific Giardia duodenalis genotype E in a sheep farm from Brazil. Fecal specimens were collected from 100 animals and screened for the presence of G. duodenalis and Cryptosporidium spp. by enzyme immunoassay (EIA) and polymerase chain reaction (PCR). Restriction fragment length polymorphism (RFLP) and sequence analysis of selected samples was used to confirm the species and to characterize the isolates. Of 100 specimens, 34 were positive for Giardia (34%) and 25 were positive for Cryptosporidium (25%). The prevalence of Giardia and Cryptosporidium was higher in lambs than in ewes. Co-infection was observed in 14% of animals. All G. duodenalis isolates belonged to genotype E. The genetic characterization performed in 22 Cryptosporidium-positive samples revealed the presence of zoonotic C. ubiquitum and C. parvum in 76% (19/25) and 12% (3/25) of infected animals, respectively. The presence of zoonotic Cryptosporidium subtypes in lambs was of epidemiological and public health relevance.
Mammalian serum is essential for the growth of Giardia duodenalis cultivated under axenic conditions. Unfortunately, some factors present in bovine serum used as supplement in the culture medium may inhibit protozoal growth and activity. TYI-33-PACSR is a TYI medium supplemented with a serum replacement (PACSR) made up of Earle’s amino acid solution, Diamond’s vitamin-tween 80 mixtures and LCR (a lipid-cholesterol — rich mixture). PACSR was previously used in the culture media for axenic cultivation of Entamoeba histolytica and Trichomonas vaginalis. The main objective of this work was to demonstrate that TYI-33-PACSR is useful for axenic cultivation of G. duodenalis. Additionally, the activity of phospholipase A2 (PLA A2) in the sub-cellular vesicular fraction (P30) of G. duodenalis grown in TYI-S-33 and TYI-33-PACSR was compared. All strains of Giardia grown in TYI-33-PACSR reached relative cellular densities of 91 to 95% compared to controls growing in serum-supplemented TYI-S-33 medium. Additionally, PLA A2 activity was similar in the P30 sub-cellular fraction obtained from trophozoites growing in TYI-S-33 and TYI-33-PACSR. Thus, TYI-33-PACSR could be useful in analyzing the biological properties of G. duodenalis in the absence of serum.
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