1 c2khpA_
99.9
58
PDB header: electron transportChain: A: PDB Molecule: glutaredoxin;
PDBTitle: solution structure of glutaredoxin from brucella melitensis
2 d1fova_
99.9
99
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
3 c2klxA_
99.9
46
PDB header: oxidoreductaseChain: A: PDB Molecule: glutaredoxin;
PDBTitle: solution structure of glutaredoxin from bartonella henselae str.2 houston
4 c3qmxA_
99.9
61
PDB header: electron transportChain: A: PDB Molecule: glutaredoxin a;
PDBTitle: x-ray crystal structure of synechocystis sp. pcc 6803 glutaredoxin a
5 c3fzaA_
99.9
33
PDB header: oxidoreductaseChain: A: PDB Molecule: glutaredoxin;
PDBTitle: crystal structure of poplar glutaredoxin s12 in complex with2 glutathione and beta-mercaptoethanol
6 c2e7pC_
99.9
37
PDB header: electron transportChain: C: PDB Molecule: glutaredoxin;
PDBTitle: crystal structure of the holo form of glutaredoxin c1 from populus2 tremula x tremuloides
7 c2ht9A_
99.9
33
PDB header: oxidoreductaseChain: A: PDB Molecule: glutaredoxin-2;
PDBTitle: the structure of dimeric human glutaredoxin 2
8 c3h8qB_
99.9
37
PDB header: oxidoreductaseChain: B: PDB Molecule: thioredoxin reductase 3;
PDBTitle: crystal structure of glutaredoxin domain of human thioredoxin2 reductase 3
9 d1wika_
99.9
29
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
10 c1ykaA_
99.9
32
PDB header: electron transportChain: A: PDB Molecule: monothiol glutaredoxin ydhd;
PDBTitle: solution structure of grx4, a monothiol glutaredoxin from2 e. coli.
11 c2hzfA_
99.9
30
PDB header: electron transport, oxidoreductaseChain: A: PDB Molecule: glutaredoxin-1;
PDBTitle: crystal structures of a poxviral glutaredoxin in the oxidized and2 reduced states show redox-correlated structural changes
12 d1t1va_
99.9
23
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: SH3BGR (SH3-binding, glutamic acid-rich protein-like)
13 d1jhba_
99.9
37
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
14 c2jadA_
99.9
35
PDB header: electron transportChain: A: PDB Molecule: yellow fluorescent protein glutaredoxin fusion
PDBTitle: yellow fluorescent protein - glutaredoxin fusion protein
15 d1ktea_
99.9
33
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
16 c3l4nA_
99.9
26
PDB header: oxidoreductaseChain: A: PDB Molecule: monothiol glutaredoxin-6;
PDBTitle: crystal structure of yeast monothiol glutaredoxin grx6
17 c3ipzA_
99.9
26
PDB header: electron transport, oxidoreductaseChain: A: PDB Molecule: monothiol glutaredoxin-s14, chloroplastic;
PDBTitle: crystal structure of arabidopsis monothiol glutaredoxin atgrxcp
18 c3d5jB_
99.9
29
PDB header: oxidoreductaseChain: B: PDB Molecule: glutaredoxin-2, mitochondrial;
PDBTitle: structure of yeast grx2-c30s mutant with glutathionyl mixed2 disulfide
19 c3c1sA_
99.9
38
PDB header: oxidoreductaseChain: A: PDB Molecule: glutaredoxin-1;
PDBTitle: crystal structure of grx1 in glutathionylated form
20 c2jacA_
99.9
34
PDB header: electron transportChain: A: PDB Molecule: glutaredoxin-1;
PDBTitle: glutaredoxin grx1p c30s mutant from yeast
21 c2wulB_
not modelled
99.9
26
PDB header: oxidoreductaseChain: B: PDB Molecule: glutaredoxin related protein 5;
PDBTitle: crystal structure of the human glutaredoxin 5 with bound2 glutathione in an fes cluster
22 c3gx8A_
not modelled
99.9
29
PDB header: electron transportChain: A: PDB Molecule: monothiol glutaredoxin-5, mitochondrial;
PDBTitle: structural and biochemical characterization of yeast2 monothiol glutaredoxin grx5
23 c3lgcA_
not modelled
99.8
43
PDB header: unknown functionChain: A: PDB Molecule: glutaredoxin 1;
PDBTitle: crystal structure of glutaredoxin 1 from francisella2 tularensis
24 c1nm3B_
not modelled
99.8
47
PDB header: electron transportChain: B: PDB Molecule: protein hi0572;
PDBTitle: crystal structure of heamophilus influenza hybrid-prx5
25 d1nm3a1
not modelled
99.8
47
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
26 c3ic4A_
not modelled
99.8
31
PDB header: oxidoreductaseChain: A: PDB Molecule: glutaredoxin (grx-1);
PDBTitle: the crystal structure of the glutaredoxin(grx-1) from archaeoglobus2 fulgidus
27 c2ct6A_
not modelled
99.8
20
PDB header: structural genomics, unknown functionChain: A: PDB Molecule: sh3 domain-binding glutamic acid-rich-like
PDBTitle: solution structure of the sh3 domain-binding glutamic acid-2 rich-like protein 2
28 d1egoa_
not modelled
99.8
39
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
29 d1h75a_
not modelled
99.7
23
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
30 c1u6tA_
not modelled
99.7
23
PDB header: protein binding, signaling proteinChain: A: PDB Molecule: sh3 domain-binding glutamic acid-rich-like
PDBTitle: crystal structure of the human sh3 binding glutamic-rich2 protein like
31 d1abaa_
not modelled
99.7
31
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
32 d1r7ha_
not modelled
99.7
23
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
33 c3nznA_
not modelled
99.7
26
PDB header: oxidoreductaseChain: A: PDB Molecule: glutaredoxin;
PDBTitle: the crystal structure of the glutaredoxin from methanosarcina mazei2 go1
34 d1wjka_
not modelled
98.9
19
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
35 c2v6oA_
not modelled
98.8
24
PDB header: oxidoreductaseChain: A: PDB Molecule: thioredoxin glutathione reductase;
PDBTitle: structure of schistosoma mansoni thioredoxin-glutathione2 reductase (smtgr)
36 d1oyja2
not modelled
98.8
9
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
37 d1g7oa2
not modelled
98.8
20
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
38 d1k0ma2
not modelled
98.7
21
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
39 d1hyua4
not modelled
98.7
17
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: PDI-like
40 c3ic8D_
not modelled
98.7
16
PDB header: structural genomics, unknown functionChain: D: PDB Molecule: uncharacterized gst-like proteinprotein;
PDBTitle: the crystal structure of a gst-like protein from pseudomonas syringae2 to 2.4a
41 c3lykA_
not modelled
98.7
20
PDB header: transport proteinChain: A: PDB Molecule: stringent starvation protein a homolog;
PDBTitle: structure of stringent starvation protein a homolog from2 haemophilus influenzae
42 d1gwca2
not modelled
98.6
12
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
43 c2fgxA_
not modelled
98.6
24
PDB header: structural genomics, unknown functionChain: A: PDB Molecule: putative thioredoxin;
PDBTitle: solution nmr structure of protein ne2328 from nitrosomonas2 europaea. northeast structural genomics consortium target3 net3.
44 d1eema2
not modelled
98.6
22
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
45 c1zypB_
not modelled
98.6
19
PDB header: oxidoreductaseChain: B: PDB Molecule: alkyl hydroperoxide reductase subunit f;
PDBTitle: synchrotron reduced form of the n-terminal domain of2 salmonella typhimurium ahpf
46 c1k0nB_
not modelled
98.6
21
PDB header: metal transportChain: B: PDB Molecule: chloride intracellular channel protein 1;
PDBTitle: chloride intracellular channel 1 (clic1) complexed with glutathione
47 d1e6ba2
not modelled
98.6
16
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
48 c1z9hB_
not modelled
98.6
23
PDB header: isomeraseChain: B: PDB Molecule: membrane-associated prostaglandin e synthase-2;
PDBTitle: microsomal prostaglandin e synthase type-2
49 d1k0da2
not modelled
98.6
12
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
50 c1g7oA_
not modelled
98.6
19
PDB header: oxidoreductaseChain: A: PDB Molecule: glutaredoxin 2;
PDBTitle: nmr solution structure of reduced e. coli glutaredoxin 2
51 d1ttza_
not modelled
98.6
21
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
52 d1v2aa2
not modelled
98.5
14
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
53 c2aheA_
not modelled
98.5
21
PDB header: metal transportChain: A: PDB Molecule: chloride intracellular channel protein 4;
PDBTitle: crystal structure of a soluble form of clic4. intercellular2 chloride ion channel
54 d1ljra2
not modelled
98.5
9
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
55 c1oyjC_
not modelled
98.5
9
PDB header: transferaseChain: C: PDB Molecule: glutathione s-transferase;
PDBTitle: crystal structure solution of rice gst1 (osgstu1) in complex with2 glutathione.
56 c2vo4A_
not modelled
98.5
13
PDB header: transferaseChain: A: PDB Molecule: 2,4-d inducible glutathione s-transferase;
PDBTitle: glutathione transferase from glycine max
57 d1pn9a2
not modelled
98.5
13
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
58 d1z3ea1
not modelled
98.5
29
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: ArsC-like
59 c2kokA_
not modelled
98.4
21
PDB header: oxidoreductaseChain: A: PDB Molecule: arsenate reductase;
PDBTitle: solution structure of an arsenate reductase (arsc) related protein2 from brucella melitensis. seattle structural genomics center for3 infectious disease target braba.00007.a.
60 d1z9ha2
not modelled
98.4
23
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
61 d1k0dd2
not modelled
98.4
15
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
62 c1k0dB_
not modelled
98.4
13
PDB header: gene regulationChain: B: PDB Molecule: ure2 protein;
PDBTitle: ure2p in complex with glutathione
63 c3l78A_
not modelled
98.4
32
PDB header: transcriptionChain: A: PDB Molecule: regulatory protein spx;
PDBTitle: the crystal structure of smu.1142c from streptococcus mutans ua159
64 c3kp9A_
not modelled
98.4
23
PDB header: blood coagulation,oxidoreductaseChain: A: PDB Molecule: vkorc1/thioredoxin domain protein;
PDBTitle: structure of a bacterial homolog of vitamin k epoxide reductase
65 d1fw1a2
not modelled
98.4
16
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
66 c1yy7A_
not modelled
98.4
15
PDB header: transcriptionChain: A: PDB Molecule: stringent starvation protein a;
PDBTitle: crystal structure of stringent starvation protein a (sspa),2 an rna polymerase-associated transcription factor
67 c1gwcC_
not modelled
98.3
12
PDB header: transferaseChain: C: PDB Molecule: glutathione s-transferase tsi-1;
PDBTitle: the structure of a tau class glutathione s-transferase from2 wheat, active in herbicide detoxification
68 c3qagA_
not modelled
98.3
20
PDB header: transferaseChain: A: PDB Molecule: glutathione s-transferase omega-2;
PDBTitle: human glutathione transferase o2 with glutathione -new crystal form
69 d1axda2
not modelled
98.3
19
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
70 c1zl9A_
not modelled
98.3
8
PDB header: transferaseChain: A: PDB Molecule: glutathione s-transferase 5;
PDBTitle: crystal structure of a major nematode c.elegans specific gst (ce01613)
71 c3fy7B_
not modelled
98.3
25
PDB header: transport proteinChain: B: PDB Molecule: chloride intracellular channel protein 3;
PDBTitle: crystal structure of homo sapiens clic3
72 d1aw9a2
not modelled
98.3
19
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
73 d1gnwa2
not modelled
98.3
14
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
74 d1nhoa_
not modelled
98.3
30
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
75 c1ljrB_
not modelled
98.2
9
PDB header: transferaseChain: B: PDB Molecule: glutathione s-transferase;
PDBTitle: glutathione transferase (hgst t2-2) from human
76 c3fz4A_
not modelled
98.2
24
PDB header: oxidoreductaseChain: A: PDB Molecule: putative arsenate reductase;
PDBTitle: the crystal structure of a possible arsenate reductase from2 streptococcus mutans ua159
77 d1jlva2
not modelled
98.2
11
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
78 d1iloa_
not modelled
98.2
23
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
79 d1jlwa2
not modelled
98.2
10
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
80 c2r4vA_
not modelled
98.2
23
PDB header: transport proteinChain: A: PDB Molecule: chloride intracellular channel protein 2;
PDBTitle: structure of human clic2, crystal form a
81 c2jl4A_
not modelled
98.2
17
PDB header: isomeraseChain: A: PDB Molecule: maleylpyruvate isomerase;
PDBTitle: holo structure of maleyl pyruvate isomerase, a bacterial2 glutathione-s-transferase in zeta class
82 c3lypA_
not modelled
98.2
19
PDB header: transcriptionChain: A: PDB Molecule: stringent starvation protein a;
PDBTitle: structure of stringent starvation protein a homolog from pseudomonas2 fluorescens
83 c3kp8A_
not modelled
98.2
21
PDB header: oxidoreductaseChain: A: PDB Molecule: vkorc1/thioredoxin domain protein;
PDBTitle: the thioredoxin-like domain of a vkor homolog from2 synechococcus sp.
84 c3gkxB_
not modelled
98.1
17
PDB header: structural genomics, unknown functionChain: B: PDB Molecule: putative arsc family related protein;
PDBTitle: crystal structure of putative arsc family related protein from2 bacteroides fragilis
85 c1hyuA_
not modelled
98.1
16
PDB header: oxidoreductaseChain: A: PDB Molecule: alkyl hydroperoxide reductase subunit f;
PDBTitle: crystal structure of intact ahpf
86 c2cz2A_
not modelled
98.1
22
PDB header: isomerase, transferaseChain: A: PDB Molecule: maleylacetoacetate isomerase;
PDBTitle: crystal structure of glutathione transferase zeta 1-12 (maleylacetoacetate isomerase) from mus musculus (form-1 crystal)
87 d1r5aa2
not modelled
98.1
10
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
88 c3rbtD_
not modelled
98.1
21
PDB header: transferaseChain: D: PDB Molecule: glutathione transferase o1;
PDBTitle: crystal structure of glutathione s-transferase omega 3 from the2 silkworm bombyx mori
89 c1r5aA_
not modelled
98.1
10
PDB header: transferaseChain: A: PDB Molecule: glutathione transferase;
PDBTitle: glutathione s-transferase
90 c1v2aD_
not modelled
98.0
14
PDB header: transferaseChain: D: PDB Molecule: glutathione transferase gst1-6;
PDBTitle: glutathione s-transferase 1-6 from anopheles dirus species b
91 c1eemA_
not modelled
98.0
16
PDB header: transferaseChain: A: PDB Molecule: glutathione-s-transferase;
PDBTitle: glutathione transferase from homo sapiens
92 c3lxzD_
not modelled
98.0
20
PDB header: transferaseChain: D: PDB Molecule: glutathione s-transferase family protein;
PDBTitle: structure of probable glutathione s-transferase(pp0183) from2 pseudomonas putida
93 c2c3nB_
not modelled
98.0
10
PDB header: transferaseChain: B: PDB Molecule: glutathione s-transferase theta 1;
PDBTitle: human glutathione-s-transferase t1-1, apo form
94 c1gnwA_
not modelled
98.0
14
PDB header: transferaseChain: A: PDB Molecule: glutathione s-transferase;
PDBTitle: structure of glutathione s-transferase
95 c2imiA_
not modelled
98.0
17
PDB header: transferaseChain: A: PDB Molecule: epsilon-class glutathione s-transferase;
PDBTitle: structures of an insect epsilon-class glutathione s-2 transferase from the malaria vector anopheles gambiae:3 evidence for high ddt-detoxifying activity
96 c3bbyA_
not modelled
98.0
25
PDB header: transferaseChain: A: PDB Molecule: uncharacterized gst-like protein yfcf;
PDBTitle: crystal structure of glutathione s-transferase (np_416804.1) from2 escherichia coli k12 at 1.85 a resolution
97 c3nivD_
not modelled
98.0
20
PDB header: isomeraseChain: D: PDB Molecule: glutathione s-transferase;
PDBTitle: the crystal structure of glutathione s-transferase from legionella2 pneumophila
98 d1rk4a2
not modelled
98.0
19
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
99 d1rw1a_
not modelled
98.0
16
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: ArsC-like
100 d1pd212
not modelled
98.0
5
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Glutathione S-transferase (GST), N-terminal domain
101 c1byeA_
not modelled
97.9
19
PDB header: transferaseChain: A: PDB Molecule: protein (glutathione s-transferase);
PDBTitle: glutathione s-transferase i from mais in complex with2 atrazine glutathione conjugate
102 c3f6fA_
not modelled
97.9
15
PDB header: transferaseChain: A: PDB Molecule: cg18548-pa (ip02196p) (ip02193p);
PDBTitle: crystal structure of glutathione transferase dmgstd10 from2 drosophila melanogaster
103 c3f0iA_
not modelled
97.9
25
PDB header: oxidoreductaseChain: A: PDB Molecule: arsenate reductase;
PDBTitle: arsenate reductase from vibrio cholerae.
104 c1jlvA_
not modelled
97.9
13
PDB header: transferaseChain: A: PDB Molecule: glutathione transferase gst1-3;
PDBTitle: anopheles dirus species b glutathione s-transferases 1-3
105 c3rdwB_
not modelled
97.9
18
PDB header: oxidoreductaseChain: B: PDB Molecule: putative arsenate reductase;
PDBTitle: putative arsenate reductase from yersinia pestis
106 c1oktA_
not modelled
97.9
13
PDB header: transferaseChain: A: PDB Molecule: glutathione s-transferase;
PDBTitle: x-ray structure of glutathione s-transferase from the2 malarial parasite plasmodium falciparum
107 c2on7A_
not modelled
97.9
11
PDB header: transferaseChain: A: PDB Molecule: na glutathione s-transferase 1;
PDBTitle: structure of nagst-1
108 c3ergA_
not modelled
97.9
24
PDB header: transferaseChain: A: PDB Molecule: glutathione s-transferase 2;
PDBTitle: crystal structure of gtt2 from saccharomyces cerevisiae in complex2 with glutathione sulfnate
109 d1zmaa1
not modelled
97.9
25
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: Thioltransferase
110 c1vf1A_
not modelled
97.9
18
PDB header: transferaseChain: A: PDB Molecule: glutathione s-transferase 3;
PDBTitle: cgsta1-1 in complex with glutathione
111 c3m3mA_
not modelled
97.9
14
PDB header: transferaseChain: A: PDB Molecule: glutathione s-transferase;
PDBTitle: crystal structure of glutathione s-transferase from pseudomonas2 fluorescens [pf-5]
112 c3cbuB_
not modelled
97.8
15
PDB header: transferaseChain: B: PDB Molecule: probable gst-related protein;
PDBTitle: crystal structure of a putative glutathione s-transferase (reut_a1011)2 from ralstonia eutropha jmp134 at 2.05 a resolution
113 c2l6dA_
not modelled
97.8
25
PDB header: oxidoreductaseChain: A: PDB Molecule: thioredoxin;
PDBTitle: solution structure of desulfothioredoxin from desulfovibrio vulgaris2 hildenborough in its reduced form
114 d1j9ba_
not modelled
97.8
18
Fold: Thioredoxin foldSuperfamily: Thioredoxin-likeFamily: ArsC-like
115 c3m0fA_
not modelled
97.8
13
PDB header: transferaseChain: A: PDB Molecule: uncharacterized protein gst_n;
PDBTitle: crystal structure of glutathione s transferase in complex2 with glutathione from pseudomonas fluorescens
116 c1aw9A_
not modelled
97.8
19
PDB header: transferaseChain: A: PDB Molecule: glutathione s-transferase iii;
PDBTitle: structure of glutathione s-transferase iii in apo form
117 c2on5E_
not modelled
97.8
7
PDB header: transferaseChain: E: PDB Molecule: na glutathione s-transferase 2;
PDBTitle: structure of nagst-2
118 c2ws2B_
not modelled
97.8
8
PDB header: transferaseChain: B: PDB Molecule: glutathione s-transferase;
PDBTitle: the 2 angstrom structure of a nu-class gst from haemonchus contortus
119 c1iyiA_
not modelled
97.8
7
PDB header: isomeraseChain: A: PDB Molecule: hematopoietic prostagladin d synthase;
PDBTitle: crystal structure of hematopoietic prostaglandin d synthase
120 c2hnlB_
not modelled
97.7
13
PDB header: transferaseChain: B: PDB Molecule: glutathione s-transferase 1;
PDBTitle: structure of the prostaglandin d synthase from the parasitic nematode2 onchocerca volvulus