Jump to content

Teicoplanin

From Wikipedia, the free encyclopedia

Teicoplanin
Clinical data
Pronunciation/ˌtkˈplnɪn/
TY-koh-PLAY-nin
Trade namesTargocid
AHFS/Drugs.comInternational Drug Names
Pregnancy
category
  • AU: B3
Routes of
administration
Intravenous, intramuscular
ATC code
Legal status
Legal status
  • AU: S4 (Prescription only)[1]
  • UK: POM (Prescription only)
  • EU: Rx-only[2]
Pharmacokinetic data
Bioavailability90% (given IM)
Protein binding90% to 95%
MetabolismNil
Elimination half-life70 to 100 hours
ExcretionKidney (97% unchanged)
Identifiers
  • Ristomycin A 34-O-[2-(acetylamino)-2-deoxy-.beta.-D-glucopyranosyl]-22,31-dichloro-7-demethyl-64-O-demethyl-19-deoxy-56-O-[2-deoxy-2-[(8-methyl-1-oxononyl)amino]-.beta.-D-glucopyranosyl]-42-O-.alpha.-D-mannopyranosyl-
CAS Number
PubChem CID
DrugBank
ChemSpider
UNII
KEGG
ChEMBL
NIAID ChemDB
CompTox Dashboard (EPA)
Chemical and physical data
FormulaVariable
Molar mass1564.3 to 1907.7 g/mol
Melting point260 °C (500 °F) (dec.)
  • InChI=1S/C89H99Cl2N9O33/c1-34(2)9-7-5-4-6-8-10-61(109)95-69-75(114)72(111)59(32-102)130-88(69)133-79-56-26-41-27-57(79)127-53-18-14-39(24-48(53)91)78(132-87-68(93-35(3)104)74(113)71(110)58(31-101)129-87)70-85(122)99-67(86(123)124)46-29-43(106)30-55(128-89-77(116)76(115)73(112)60(33-103)131-89)62(46)45-23-38(13-15-50(45)107)64(82(119)100-70)97-84(121)66(41)98-83(120)65-40-21-42(105)28-44(22-40)125-54-25-37(12-16-51(54)108)63(92)81(118)94-49(80(117)96-65)20-36-11-17-52(126-56)47(90)19-36/h11-19,21-30,34,49,58-60,63-78,87-89,101-103,105-108,110-116H,4-10,20,31-33,92H2,1-3H3,(H,93,104)(H,94,118)(H,95,109)(H,96,117)(H,97,121)(H,98,120)(H,99,122)(H,100,119)(H,123,124)/t49-,58-,59-,60-,63+,64-,65+,66-,67-,68-,69-,70+,71-,72-,73-,74-,75-,76+,77+,78-,87+,88+,89+/m1/s1 checkY
  • Key:FHBQKTSCJKPYIO-OXIGXJDJSA-N checkY
 ☒NcheckY (what is this?)  (verify)

Teicoplanin is an semisynthetic glycopeptide antibiotic with a spectrum of activity similar to vancomycin. Its mechanism of action is to inhibit bacterial cell wall[3] peptidoglycan[4] synthesis. It is used in the prophylaxis and treatment of serious infections caused by Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and Enterococcus faecalis.[3]

Teicoplanin is widely available in many European, Asian, and South American countries, however it is not currently approved by the US Food and Drug Administration and is not commercially available in the United States.[5] Teicoplanin is marketed by Sanofi-Aventis under the trade name Targocid.[6] Other trade names include Ticocin marketed by Cipla(India).[citation needed]

Its strength is considered to be due to the length of the hydrocarbon chain.[7]

History

[edit]

Teicoplanin was first isolated in 1978 from Actinoplanes teichomyceticus (ATCC 31121), a rare species of actinobacteria in the family Micromonosporaceae. The bacteria were obtained from a soil sample collected in Nimodi Village, Indore, India.[6][8][9] The chemical structure of teicoplanin was determined and published in 1984.[6]

Teicoplanin was first introduced into clinical use in 1984.[10] Following the publication of studies demonstrating its efficacy against infections such as bone and soft tissue infections, endocarditis, pneumonia, and sepsis in 1986, it received regulatory approval in Europe in 1988.[6][10][11]

The biosynthetic pathway leading to teicoplanin, as well as the regulatory circuit governing the biosynthesis, were studied intensively in recent years, allowing for the creation of an integrated model of its biosynthesis.[12]

Indications

[edit]

Teicoplanin treats a wide range of infections with Gram-positive bacteria, including endocarditis, sepsis, soft tissue and skin infections, and venous catheter-associated infections.[13]

Studies have investigated the use of oral teicoplanin in the treatment of pseudomembranous colitis and Clostridioides difficile-associated diarrhea, finding it to demonstrate efficacy comparable to that of vancomycin.[14][15][16]

Susceptible organisms

[edit]

Teicoplanin has demonstrated in vitro efficacy against Gram-positive bacteria including staphylococci (including MRSA), streptococci, enterococci, and against anaerobic Gram-positive bacteria including Clostridium spp. Teicoplanin is ineffective against Gram-negative bacteria as the large, polar molecules of the compound are unable to pass through the external membrane of these organisms.[13] The following represents MIC susceptibility data for a few medically significant pathogens:[4]

  • Clostridioides difficile: 0.06 μg/ml - 0.5 μg/ml
  • Staphylococcus aureus: ≤0.06 μg/ml - ≥128 μg/ml
  • Staphylococcus epidermidis: ≤0.06 μg/ml - 32 μg/ml

Pharmacology

[edit]

Pharmacokinetics

[edit]

Due to poor oral absorption, teicoplanin requires intravenous or intramuscular administration for systemic effect. Intramuscular administration achieves approximately 90% bioavailability. The drug exhibits high protein binding (90-95%) and is primarily eliminated through the kidneys unchanged, with minimal liver metabolism (2-3%) via hydroxylation. Clearance is reduced in patients with kidney impairment and is not significantly removed by hemodialysis. Teicoplanin exhibits a long half-life of 45-70 hours, allowing for once-daily dosing after loading doses.[6][13][17][18][19]

Pharmacodynamics

[edit]

Teicoplanin is a glycopeptide antibiotic that inhibits bacterial cell wall synthesis. It binds to the D-alanyl-D-alanine (D-Ala-D-Ala) terminus of the peptidoglycan precursor, preventing the transpeptidation reaction necessary for cell wall cross-linking. This binding also interferes with the polymerization of peptidoglycan, ultimately leading to cell death.[6]

In addition to its binding to the D-Ala-D-Ala terminus, teicoplanin may also interact with the lipid II substrate in the bacterial cell membrane through its hydrophobic tail. This interaction could facilitate the antibiotic's proximity to the nascent peptidoglycan, enhancing its inhibitory effect. However, this mechanism has not been fully confirmed.[6]

Adverse effects

[edit]

Adverse effects of teicoplanin are usually limited to local effects or hypersensitivity reactions. While there is potential for nephrotoxicity and ototoxicity, the incidence of such organ toxicity is rare if recommended serum concentrations are successfully maintained.[13]

Considerations

[edit]

Reduced kidney function slows teicoplanin clearance, consequently increasing its elimination half-life. Elimination half-life is longer in the elderly due to the reduced kindey function in this population.[13]

Chemistry

[edit]

Teicoplanin (TARGOCID, marketed by Sanofi Aventis Ltd) is actually a mixture of several compounds, five major (named teicoplanin A2-1 through A2-5) and four minor (named teicoplanin RS-1 through RS-4).[17][20] All teicoplanins share a same glycopeptide core, termed teicoplanin A3-1 — a fused ring structure to which two carbohydrates (mannose and N-acetylglucosamine) are attached. The major and minor components also contain a third carbohydrate moietyβ-D-glucosamine — and differ only by the length and conformation of a side-chain attached to it. Teicoplanin A2-4 and RS-3 have chiral side chains while all other side chains are achiral. Teicoplanin A3 lacks both the side chains as well as the β-D-glucosamine moiety.

The structures of the teicoplanin core and the side-chains that characterize the five major as well as four minor teicoplanin compounds are shown below.

Teicoplanin core (left, black) and side-chains that characterize teicoplanins A2-1 through A2-5 (middle) as well as related RS-1 through RS-4 (right). In blue: β-D-glucosamine.

Teicoplanin refers to a complex of related natural products isolated from the fermentation broth of a strain of Actinoplanes teichomyceticus,[21] consisting of a group of five structures. These structures possess a common aglycone, or core, consisting of seven amino acids bound by peptide and ether bonds to form a four-ring system. These five structures differ by the identity of the fatty acyl side-chain attached to the sugar. The origin of these seven amino acids in the biosynthesis of teicoplanin was studied by 1H and 13C nuclear magnetic resonance.[22] The studies indicate amino acids 4-Hpg, 3-Cl-Tyr, and 3-chloro-β-hydroxytyrosine are derived from tyrosine, and the amino acid 3,5-dihydroxyphenylglycine (3,5-Dpg) is derived from acetate. Teicoplanin contains 6 non-proteinogenic amino acids and three sugar moieties, N-acyl-β-D-glucosamine, N-acetyl-β-D-glucosamine, and D-mannose.

Gene cluster

[edit]

The study of the genetic cluster encoding the biosynthesis of teicoplanin identified 49 putative open reading frames (ORFs) involved in the compound's biosynthesis, export, resistance, and regulation. Thirty-five of these ORFs are similar to those found in other glycopeptide gene clusters. The function of each of these genes is described by Li and co-workers.[23] A summary of the gene layout and purpose is shown below.

Gene layout. The genes are numbered. The letters L and R designate transcriptional direction. The presence of the * symbol means a gene is found after NRPs, which are represented by A, B, C, and D. Based on the figure from: Li, T-L.; Huang, F.; Haydock, S. F.; Mironenko, T.; Leadlay, P. F.; Spencer, J. B. Chemistry & Biology. 2004, 11, p. 109.

[11-L] [10-L] [9-R] [8-R] [7-R] [6-R] [5-R] [4-L][3-L] [2-L] [1-R] [A-R] [B-R] [C-R] [D-R] [1*-R] [2*-R] [3*-R] [4*-R] [5*-R] [6*-R] [7*-R] [8*-R] [9*-R] [10*-R] [11*-R] [12*-R] [13*-R] [14*-R] [15*-R] [16*-R] [17*-R] [18*-R] [19*-R] [20*-R] [21*-R] [22*-R] [23*-R] [24*-R] [25*-L] [26*-L] [27*-R] [28*-R] [29*-R] [30*-R][31*-R] [32*-L] [33*-L] [34*-R]

Enzyme produced by gene sequence Regulatory proteins Other enzymes Resistant enzymes Β-hydroxy-tyrosine and 4-hydroxy-phenylglycin biosynthetic enzymes Glycosyl transferases Peptide synthetases P450 oxygenases Halogenase 3,5-dihydroxy phenylglycin biosynthetic enzymes
Genes 11, 10, 3, 2, 15*, 16*, 31* 9, 8, 1*, 2*, 4*, 11*, 13*, 21*, 26*, 27*, 30*, 32*, 33*, 34* 7, 6, 5 4, 12*, 14*, 22*, 23*, 24*, 25*, 28*, 29* 1, 3*, 10* A, B, C, D 5*, 6*, 7*, 9* 8* 17*, 18*, 19*, 20*, 23*

Heptapeptide backbone synthesis

[edit]

The heptapeptide backbone of teicoplanin is assembled by the nonribosomal peptide synthetases (NRPSs) TeiA, TeiB, TeiC and TeiD. Together these comprise seven modules, each containing a number of domains, with each module responsible for the incorporation of a single amino acid. Modules 1, 4, and 5 activate L-4-Hpg as the aminoacyl-AMP, modules 2 and 6 activate L-Tyr, and modules 3 and 7 activate L-3,5-Dpg. The activated amino acids are covalently bound to the NRPS as thioesters by a phosphopantetheine cofactor, which is attached to the peptidyl carrier protein (PCP) domain. The enzyme bound amino acids are then joined by amide bonds by the action of the condensation (C) domain.

The heptapetide of teicoplanin contains 4 D-amino acids, formed by epimerization of the activated L-amino acids. Modules 2, 4 and 5 each contain an epimerization (E) domain which catalyzes this change. Module 1 does not contain an E domain, and epimerization is proposed to be catalysed by the C domain.[24] In all, six of the seven total amino acids of the teicoplanin backbone are composed of nonproteinogenic or modified amino acids. Eleven enzymes are coordinatively induced to produce these six required residues.[25] Teicoplanin contains two chlorinated positions, 2 (3-Cl-Tyr) and 6 (3-Cl-β-Hty). The halogenase Tei8* has been acts to catalyze the halogenation of both tyrosine residues. Chlorination occurs at the amino acyl-PCP level during the biosynthesis, prior to phenolic oxidative coupling, with the possibility of tyrosine or β-hydroxytyrosine being the substrate of chlorination.[26] Hydroxylation of the tyrosine residue of module 6 also occurs in trans during the assembly of the heptapeptide backbone.

Modification after heptapeptide backbone formation

[edit]

Once the heptapeptide backbone has been formed, the linear enzyme-bound intermediate is cyclized.[25] Gene disruption studies indicate cytochrome P450 oxygenases as the enzymes that performs the coupling reactions. The X-domain in the final NRPS module is required to recruit the oxygenase enzymes.[27] OxyB forms the first ring by coupling residues 4 and 6, and OxyE then couples residues 1 and 3. OxyA couples residues 2 and 4, followed by the formation of a C-C bond between residues 5 and 7 by OxyC.[28] The regioselectivity and atropisomer selectivity of these probable one-electron coupling reactions has been suggested to be due to the folding and orientation requirements of the partially crossed-linked substrates in the enzyme active site.[25] The coupling reactions are shown below.

Oxidative cross-linkings steps during teicoplanin biosynthesis, catalysed by cytochrome P450 oxidases OxyB, E, A and C.

Specific glycosylation has been shown to occur after the formation of the heptpeptide aglycone.[29] Three separate glycosyl transferases are required for the glycosylation of the teicoplanin aglycone. Tei10* catalyses the addition of GlcNAc to residue 4, followed by deacetylation by Tei2*. The acyl chain (produced by the action of Tei30* and Tei13*) is then added by Tei11*. Tei1 then adds a second GlcNAc to the β-hydroxyl group of residue 6, followed by mannosylation of residue 7 catalysed by Tei3*.[30]

Research

[edit]

Researchers have explored the potential of teicoplanin as an antiviral agent against various viruses, including SARS-CoV-2. Laboratory studies indicate that teicoplanin inhibits cathepsin L, a host cell protease utilized by SARS-CoV-2 for cell entry via the endocytic pathway. In vitro experiments have demonstrated teicoplanin's ability to reduce SARS-CoV-2 infection, with reported IC50 values in the low micromolar range. This suggests potential efficacy against various SARS-CoV-2 variants due to conserved cathepsin L cleavage sites on the SARS-CoV-2 spike protein. Animal studies have also shown a protective effect against SARS-CoV-2 infection with teicoplanin pre-treatment.[6][31][32]

References

[edit]
  1. ^ "Prescription medicines: registration of new generic medicines and biosimilar medicines, 2017". Therapeutic Goods Administration (TGA). 21 June 2022. Retrieved 30 March 2024.
  2. ^ Human Medicines Evaluation Division (10 December 2020). "Active substance: teicoplanin" (PDF). List of nationally authorised medicinal products. European Medicines Agency.
  3. ^ a b Reynolds PE (November 1989). "Structure, biochemistry and mechanism of action of glycopeptide antibiotics". European Journal of Clinical Microbiology & Infectious Diseases. 8 (11): 943–950. doi:10.1007/BF01967563. PMID 2532132. S2CID 21551939.
  4. ^ a b "Teicoplanin Susceptibility and Minimum Inhibitory Concentration (MIC) Data" (PDF). TOKU-E.
  5. ^ Murray BE, Arias CA, Nannini EC (2014). Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases (8 ed.). Philadelphia, PA: Elsevier Health Sciences. p. 377. ISBN 978-1-4557-4801-3.
  6. ^ a b c d e f g h Vimberg V (November 2021). "Teicoplanin-A New Use for an Old Drug in the COVID-19 Era?". Pharmaceuticals (Basel, Switzerland). 14 (12): 1227. doi:10.3390/ph14121227. PMC 8708781. PMID 34959628.
  7. ^ Gilpin M, Milner P (1997). "Resisting changes -- Over the past 40 years the glycopeptide antibiotics have played a crucial role in treating bacterial infections. But how long can it continue?". Royal Society of Chemistry. Archived from the original on 2002-12-21. Retrieved 2006-10-15. - includes picture of Teicoplanin's structure.
  8. ^ "Actinoplanes teichomyceticus Parenti et al". ATCC (American Type Culture Collection).
  9. ^ Parenti F, Beretta G, Berti M, Arioli V (April 1978). "Teichomycins, new antibiotics from Actinoplanes teichomyceticus Nov. Sp. I. Description of the producer strain, fermentation studies and biological properties". The Journal of Antibiotics. 31 (4): 276–83. doi:10.7164/antibiotics.31.276. PMID 659325.
  10. ^ a b Trautmann M, Wiedeck H, Ruhnke M, Oethinger M, Marre R (1994). "Teicoplanin: 10 years of clinical experience". Infection. 22 (6): 430–6. doi:10.1007/BF01715507. PMID 7698846.
  11. ^ Glupczynski Y, Lagast H, Van der Auwera P, Thys JP, Crokaert F, Yourassowsky E, et al. (January 1986). "Clinical evaluation of teicoplanin for therapy of severe infections caused by gram-positive bacteria". Antimicrobial Agents and Chemotherapy. 29 (1): 52–7. doi:10.1128/AAC.29.1.52. PMC 180363. PMID 2942100.
  12. ^ Yushchuk O, Ostash B, Truman AW, Marinelli F, Fedorenko V (April 2020). "Teicoplanin biosynthesis: unraveling the interplay of structural, regulatory, and resistance genes". Applied Microbiology and Biotechnology. 104 (8): 3279–3291. doi:10.1007/s00253-020-10436-y. PMID 32076781. S2CID 211170874.
  13. ^ a b c d e Campoli-Richards DM, Brogden RN, Faulds D (September 1990). "Teicoplanin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic potential". Drugs. 40 (3): 449–486. doi:10.2165/00003495-199040030-00007. PMID 2146108. S2CID 195699141.
  14. ^ Quan M, Zhang X, Fang Q, Lv X, Wang X, Zong Z (July 2024). "Fighting against Clostridioides difficile infection: Current medications". International Journal of Antimicrobial Agents. 64 (1): 107198. doi:10.1016/j.ijantimicag.2024.107198. PMID 38734214.
  15. ^ Stabholz Y, Paul M (January 2024). "The effect of antibiotic therapy for Clostridioides difficile infection on mortality and other patient-relevant outcomes: a systematic review and meta-analysis". Clinical Microbiology and Infection. 30 (1): 51–58. doi:10.1016/j.cmi.2023.09.002. PMID 37690610.
  16. ^ de Lalla F, Nicolin R, Rinaldi E, Scarpellini P, Rigoli R, Manfrin V, et al. (October 1992). "Prospective study of oral teicoplanin versus oral vancomycin for therapy of pseudomembranous colitis and Clostridium difficile-associated diarrhea". Antimicrobial Agents and Chemotherapy. 36 (10): 2192–2196. doi:10.1128/AAC.36.10.2192. PMC 245474. PMID 1444298.
  17. ^ a b Bernareggi A, Borghi A, Borgonovi M, Cavenaghi L, Ferrari P, Vékey K, et al. (August 1992). "Teicoplanin metabolism in humans". Antimicrobial Agents and Chemotherapy. 36 (8): 1744–1749. doi:10.1128/AAC.36.8.1744. PMC 192040. PMID 1416858.
  18. ^ Wang Y, Yao F, Chen S, Ouyang X, Lan J, Wu Z, et al. (2023). "Optimal Teicoplanin Dosage Regimens in Critically Ill Patients: Population Pharmacokinetics and Dosing Simulations Based on Renal Function and Infection Type". Drug Design, Development and Therapy. 17: 2259–2271. doi:10.2147/DDDT.S413662. PMC 10404122. PMID 37546521.
  19. ^ Pandey A, Nikam AN, Shreya AB, Mutalik SP, Gopalan D, Kulkarni S, et al. (September 2020). "Potential therapeutic targets for combating SARS-CoV-2: Drug repurposing, clinical trials and recent advancements". Life Sciences. 256: 117883. doi:10.1016/j.lfs.2020.117883. PMC 7263255. PMID 32497632.
  20. ^ Geibel C, Olfert M, Knappe C, Serafimov K, Lämmerhofer M (February 2023). "Branched medium-chain fatty acid profiling and enantiomer separation of anteiso-forms of teicoplanin fatty acyl side chain RS3 using UHPLC-MS/MS with polysaccharide columns". Journal of Pharmaceutical and Biomedical Analysis. 224: 115162. doi:10.1016/j.jpba.2022.115162. PMID 36423498. S2CID 253529204.
  21. ^ Jung HM, Jeya M, Kim SY, Moon HJ, Kumar Singh R, Zhang YW, et al. (September 2009). "Biosynthesis, biotechnological production, and application of teicoplanin: current state and perspectives". Applied Microbiology and Biotechnology. 84 (3): 417–428. doi:10.1007/s00253-009-2107-4. PMID 19609520. S2CID 45038487.
  22. ^ Heydorn A, Petersen BO, Duus JO, Bergmann S, Suhr-Jessen T, Nielsen J (March 2000). "Biosynthetic studies of the glycopeptide teicoplanin by (1)H and (13)C NMR". The Journal of Biological Chemistry. 275 (9): 6201–6206. doi:10.1074/jbc.275.9.6201. PMID 10692413.
  23. ^ Li TL, Huang F, Haydock SF, Mironenko T, Leadlay PF, Spencer JB (January 2004). "Biosynthetic gene cluster of the glycopeptide antibiotic teicoplanin: characterization of two glycosyltransferases and the key acyltransferase". Chemistry & Biology. 11 (1): 107–119. doi:10.1016/j.chembiol.2004.01.001. PMID 15113000.
  24. ^ Kaniusaite M, Tailhades J, Kittilä T, Fage CD, Goode RJ, Schittenhelm RB, et al. (January 2021). "Understanding the early stages of peptide formation during the biosynthesis of teicoplanin and related glycopeptide antibiotics". The FEBS Journal. 288 (2): 507–529. doi:10.1111/febs.15350. PMID 32359003. S2CID 218481859.
  25. ^ a b c Kahne D, Leimkuhler C, Lu W, Walsh C (February 2005). "Glycopeptide and lipoglycopeptide antibiotics". Chemical Reviews. 105 (2): 425–448. doi:10.1021/cr030103a. PMID 15700951.
  26. ^ Kittilä T, Kittel C, Tailhades J, Butz D, Schoppet M, Büttner A, et al. (September 2017). "Halogenation of glycopeptide antibiotics occurs at the amino acid level during non-ribosomal peptide synthesis". Chemical Science. 8 (9): 5992–6004. doi:10.1039/C7SC00460E. PMC 5620994. PMID 28989629.
  27. ^ Haslinger K, Peschke M, Brieke C, Maximowitsch E, Cryle MJ (May 2015). "X-domain of peptide synthetases recruits oxygenases crucial for glycopeptide biosynthesis". Nature. 521 (7550): 105–109. Bibcode:2015Natur.521..105H. doi:10.1038/nature14141. PMID 25686610. S2CID 4466657.
  28. ^ Peschke M, Brieke C, Cryle MJ (October 2016). "F-O-G Ring Formation in Glycopeptide Antibiotic Biosynthesis is Catalysed by OxyE". Scientific Reports. 6 (1): 35584. Bibcode:2016NatSR...635584P. doi:10.1038/srep35584. PMC 5067714. PMID 27752135.
  29. ^ Kaplan J, Korty BD, Axelsen PH, Loll PJ (May 2001). "The role of sugar residues in molecular recognition by vancomycin". Journal of Medicinal Chemistry. 44 (11): 1837–1840. doi:10.1021/jm0005306. PMID 11356118.
  30. ^ Yushchuk O, Ostash B, Pham TH, Luzhetskyy A, Fedorenko V, Truman AW, et al. (August 2016). "Characterization of the Post-Assembly Line Tailoring Processes in Teicoplanin Biosynthesis". ACS Chemical Biology. 11 (8): 2254–2264. doi:10.1021/acschembio.6b00018. PMID 27285718.
  31. ^ Yu F, Pan T, Huang F, Ying R, Liu J, Fan H, et al. (2022). "Glycopeptide Antibiotic Teicoplanin Inhibits Cell Entry of SARS-CoV-2 by Suppressing the Proteolytic Activity of Cathepsin L". Frontiers in Microbiology. 13: 884034. doi:10.3389/fmicb.2022.884034. PMC 9096618. PMID 35572668.
  32. ^ Huang J, Ma Q, Su Z, Cheng X (October 2024). "Advancements in the Development of Anti-SARS-CoV-2 Therapeutics". International Journal of Molecular Sciences. 25 (19): 10820. doi:10.3390/ijms251910820. PMC 11477007. PMID 39409149.