The actin genes of Onchocerca volvulus

Zeng, Wenlin; Donelson, John E.

doi:10.1016/0166-6851(92)90141-6

Cited by 20 publications

(8 citation statements)

References 13 publications

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“…The cDNA nucleotide sequence has a 236 bp 5h-UTR and carries a nematode-specific SL1 at its 5h end [18,19,[23][24][25][26][27]. The 5h-UTR of the O GR mRNA is unusually long when compared with other O. ol ulus cDNAs, such as Cu\Zn superoxide dismutases, Mn superoxide dismutase and O. ol ulus glutathione S-transferase 1, where the length of the 5h-UTR is between 0 and 76 bp [25][26][27].…”

Section: Discussionmentioning

confidence: 99%

Molecular characterization and expression of Onchocerca volvulus glutathione reductase

Müller

Gilberger

Fairlamb

et al. 1997

Biochemical Journal

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Glutathione metabolism represents a potential target for anti-parasite drug design. The central role of glutathione reductase (GR) in maintenance of the thiol redox state and in anti-oxidative defence has to be evaluated in more detail in order to establish the essential function of this enzyme for the survival of the filarial parasite Onchocerca volvulus. The O. volvulus GR (OvGR) gene was cloned and sequenced. The gene is composed of 13 exons and 12 introns and spans 4065 bp. The first intron is located within the 5′-untranslated region of the gene, 16 nucleotides upstream of the translation initiation codon. Southern-blot analysis and structural characterization of the genomic sequence indicate that OvGR is encoded by a single-copy gene. Isolation of various cDNA clones revealed a polymorphism of polyadenylation initiation with no consensus polyadenylation sites in any of the cDNAs analysed. The entire cDNA is 1977 bp long and carries the nematode-specific spliced leader sequence SL1 at its 5′ end, 236 nucleotides upstream of the first in-frame methionine. The cDNA codes for a polypeptide of 462 amino acids with 53.5% sequence identity with human GR (HsGR). A total of 18 out of 19 residues contributing to glutathione binding are identical in OvGR and HsGR. However, one of the arginine residues (Arg-224 in HsGR) involved in discrimination between NADPH and NADH in all known GRs is substituted by tryptophan (Trp-207 in OvGR). The coding region of OvGR was expressed in Escherichia coli as a histidine-fusion protein, and it was established that the parasite protein still favours the binding of NADPH (Km 10.9 μM) over NADH (Km 108 μM). The histidine-fusion protein has a subunit size of 54 kDa and is active as a homodimer of 110 kDa.

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Section: Discussionmentioning

confidence: 99%

Molecular characterization and expression of Onchocerca volvulus glutathione reductase

Müller

Gilberger

Fairlamb

et al. 1997

Biochemical Journal

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“…To correct for differences in the quantity of starting material and the efficiency of DNA extraction, copy numbers of ftsZ were normalized against copies of the Onchocerca actin-2 genes. The DNA standards consisted of a single-stranded oligonucleotide of 103 bases from ftsZ (designed by use of a partial sequence from the endosymbiont of O. ochengi [14] and obtained by custom synthesis from Sigma-Genosys) and a plasmid vector (pCR 4-TOPO; Invitrogen) into which a 99-bp fragment of the O. volvulus actin-2B gene [25] had been cloned; these were diluted in 100 ng/mL yeast tRNA (Invitrogen), to prevent aggregation, and were used in duplicate 10-fold dilution series of -copies/ 6 Ϫ1 5 ϫ 10 5 ϫ 10 reaction. Primers and reporter-quencher fluorogenic oligonucleotides (probes) were designed by use of Primer3 software [26], in accordance with guidelines for the TaqMan system [27], and sequences and final optimal concentrations are displayed in table 1.…”

Section: Weeks After Treatmentmentioning

confidence: 99%

“…Primer and probe oligonucleotide sequences for quantification of the Wolbachia ftsZ gene relative to Onchocerca ochengi actin-2 genes (experiment 2). Target Although the actin-2 assay was based on the actin-2B gene sequence, it probably also amplified actin-2A, for which no published sequence is available [25].…”

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confidence: 99%

Antibiotic Chemotherapy of Onchocerciasis: In a Bovine Model, Killing of Adult Parasites Requires a Sustained Depletion of Endosymbiotic Bacteria (WolbachiaSpecies)

et al. 2005

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Development of a drug lethal to adult Onchocerca volvulus (i.e., macrofilaricide) is a research priority for the control of human onchocerciasis. Using bovine O. ochengi infections, we investigated the effects of oxytetracycline administered in a short intensive regimen (SIR; 10 mg/kg daily for 14 days), compared with a prolonged intermittent regimen (PIR; 20 mg/kg monthly for 6 months) or a combination of both (COM), on the viability of adult worms and their endosymbiotic bacteria (Wolbachia species). The long-term treatments eliminated >80% (COM) or >60% (PIR) of adult female worms (P<.001), and the COM regimen effected a sustained depletion of Wolbachia organisms. Conversely, SIR was not macrofilaricidal and only transiently depleted Wolbachia densities, which repopulated worm tissues by 24 weeks after treatment. These results unequivocally demonstrate the macrofilaricidal potential of tetracyclines against Onchocerca infection and suggest that intermittent, protracted administration will be more effective than continuous shorter term treatment.

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“…The noncoding 3Ј-end showed a consensus signal for polyadenylation (28). The 5Ј-end of the mRNA did not contain a spliced leader sequence, as confirmed by DNA sequencing and by PCR with phage DNA of the L3 library using an oligonucleotide primer corresponding to the nematode spliced leader sequence (29) and the sequence-specific primer P3.…”

Section: Characterization Of L3mentioning

confidence: 99%

Identification of Chitinase as the Immunodominant Filarial Antigen Recognized by Sera of Vaccinated Rodents

Adam

Kaltmann

Rudin

et al. 1996

Journal of Biological Chemistry

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Acanthocheilonema viteae is a parasitic nematode of rodents. We identified the chitinase of A. viteae infective stage larvae (L3) as the main target of the humoral immune response of jirds, which were protected against challenge infection after vaccination with irradiation attenuated L3. The cDNA of the L3 chitinase has been sequenced, and the deduced amino acid sequence shows significant homologies to chitinases of Brugia malayi microfilariae, insects, yeast, bacteria, and Streptomyces sp. The protein has been characterized by monoclonal antibodies and substrate activity gels. The chitinase of L3 may contribute to degrading the nematode cuticle during molting and thus represents a target of protective immune responses in a phase where the parasite is highly vulnerable. In addition, it has been shown that a similar enzyme exists in uterine microfilariae, which probably has a role in casting the egg shell.Filarial parasites, such as Onchocerca volvulus, Brugia malayi, and Wuchereria bancrofti, the causative agents of river blindness and lymphatic filariases, affect more than 100 million people throughout the tropics (1). Infection of the human host occurs by a bite of an infected arthropod. There is evidence that some individuals develop protective immunity naturally, as they do not acquire filarial infections despite high levels of local transmission (2, 3). The humoral immune response of these patients differentially recognizes antigens of infective third stage larvae (L3) (4), and it is conceivable that vaccination with such antigens could prevent the infection. As the study of protective immunity in human filariae is hampered by the host specificity of the parasites, we adopted the approach to identify immunorelevant antigens of the rodent filaria Acanthocheilonema viteae, a parasite of the jird (Meriones unguiculatus).For animal models, the vaccination with irradiation-attenuated infective larvae (L3) has been demonstrated to be the most effective way to induce protective immunity (5). Immunization of jirds with irradiation-attenuated L3 of A. viteae induces more than 90% protection against a challenge infection (6). Sera of such vaccinated animals recognize few L3 proteins. We report here on the characterization and the molecular cloning of the immunodominant antigen recognized by the humoral immune response of challenge resistant jirds, a chitinase of A. viteae L3. Chitinases were recently described from microfilariae of B. malayi (7). It was supposed that the enzymes might have a role in casting the microfilarial sheath, a modified egg shell. This structure was believed to contain chitin on biochemical grounds (8, 9) and due to its analogy with the chitincontaining egg shell of other nematodes. Interestingly, the egg shell is the only structure of nematodes known to contain chitin. However, recent reports deny the presence of chitin in the microfilarial sheath (see Refs. 10 -12) and call the chitindegrading role of filarial chitinase into question. Our characterization of L3 chitinase (an active, chitin-d...

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The actin genes of Onchocerca volvulus

Cited by 20 publications

References 13 publications

Molecular characterization and expression of Onchocerca volvulus glutathione reductase

Molecular characterization and expression of Onchocerca volvulus glutathione reductase

Antibiotic Chemotherapy of Onchocerciasis: In a Bovine Model, Killing of Adult Parasites Requires a Sustained Depletion of Endosymbiotic Bacteria (WolbachiaSpecies)

Identification of Chitinase as the Immunodominant Filarial Antigen Recognized by Sera of Vaccinated Rodents

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