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- Cho-Ngwa, Fidelis, et al.
(author)
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Identification of in vivo released products of Onchocerca with diagnostic potential, and characterization of a dominant member, the OV1CF intermediate filament
- 2011
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In: Infection, Genetics and Evolution. - : Elsevier BV. - 1567-1348 .- 1567-7257. ; 11:4, s. 778-783
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Journal article (peer-reviewed)abstract
- A sensitive and specific test for the routine diagnosis of active Onchocerca infection is currently lacking. A major drawback in the development of such a test has been the paucity of knowledge of suitable parasite antigens that can serve as targets in antigen-detection assays. In the present investigation, we employed mass spectrometry, bioinformatics and molecular techniques to identify and characterize several potentially diagnostic Onchocerca antigens in the in vivo nodular fluid, which is being investigated for the first time. The majority of the 27 identified antigens lacked a secretory signal. One of them, also identified and characterized in greater detail with the aid of previously developed monoclonal antibodies (Mabs), was a dominant circulating cytoplasmic intermediate filament protein, previously identified and named, OV1CF. Although OV1CF lacks a secretory signal in its amino acid sequence and is not detected in the pure 42h in vitro released products, it is easily detected in the in vivo nodular fluid. We conclude that these in vivo released products offer promise as diagnostics markers in onchocerciasis.
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| 2. |
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| 3. |
- Gillman, Anna, et al.
(author)
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Influenza A(H7N9) Virus Acquires Resistance-Related Neuraminidase I222T Substitution When Infected Mallards Are Exposed to Low Levels of Oseltamivir in Water
- 2015
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In: Antimicrobial Agents and Chemotherapy. - : American Society for Biochemistry and Molecular Biology. - 0066-4804 .- 1098-6596. ; 59:9, s. 5196-5202
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Journal article (peer-reviewed)abstract
- Influenza A virus (IAV) has its natural reservoir in wild waterfowl, and new human IAVs often contain gene segments originating from avian IAVs. Treatment options for severe human influenza are principally restricted to neuraminidase inhibitors (NAIs), among which oseltamivir is stockpiled in preparedness for influenza pandemics. There is evolutionary pressure in the environment for resistance development to oseltamivir in avian IAVs, as the active metabolite oseltamivir carboxylate (OC) passes largely undegraded through sewage treatment to river water where waterfowl reside. In an in vivo mallard (Anas platyrhynchos) model, we tested if low-pathogenic avian influenza A(H7N9) virus might become resistant if the host was exposed to low levels of OC. Ducks were experimentally infected, and OC was added to their water, after which infection and transmission were maintained by successive introductions of uninfected birds. Daily fecal samples were tested for IAV excretion, genotype, and phenotype. Following mallard exposure to 2.5 mu g/liter OC, the resistance-related neuraminidase (NA) I222T substitution, was detected within 2 days during the first passage and was found in all viruses sequenced from subsequently introduced ducks. The substitution generated 8-fold and 2.4-fold increases in the 50% inhibitory concentration (IC50) for OC (P < 0.001) and zanamivir (P = 0.016), respectively. We conclude that OC exposure of IAV hosts, in the same concentration magnitude as found in the environment, may result in amino acid substitutions, leading to changed antiviral sensitivity in an IAV subtype that can be highly pathogenic to humans. Prudent use of oseltamivir and resistance surveillance of IAVs in wild birds are warranted.
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| 4. |
- Gillman, Anna, et al.
(author)
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Oseltamivir Resistance in Influenza A(H6N2) Caused by an R292K Substitution in Neuraminidase Is Not Maintained in Mallards without Drug Pressure
- 2015
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:9
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Journal article (peer-reviewed)abstract
- Background Wild waterfowl is the natural reservoir of influenza A virus (IAV); hosted viruses are very variable and provide a source for genetic segments which can reassort with poultry or mammalian adapted IAVs to generate novel species crossing viruses. Additionally, wild waterfowl act as a reservoir for highly pathogenic IAVs. Exposure of wild birds to the antiviral drug oseltamivir may occur in the environment as its active metabolite can be released from sewage treatment plants to river water. Resistance to oseltamivir, or to other neuraminidase inhibitors (NAIs), in IAVs of wild waterfowl has not been extensively studied. Aim and Methods In a previous in vivo Mallard experiment, an influenza A(H6N2) virus developed oseltamivir resistance by the R292K substitution in the neuraminidase (NA), when the birds were exposed to oseltamivir. In this study we tested if the resistance could be maintained in Mallards without drug exposure. Three variants of resistant H6N2/R292K virus were each propagated during 17 days in five successive pairs of naive Mallards, while oseltamivir exposure was decreased and removed. Daily fecal samples were analyzed for viral presence, genotype and phenotype. Results and Conclusion Within three days without drug exposure no resistant viruses could be detected by NA sequencing, which was confirmed by functional NAI sensitivity testing. We conclude that this resistant N2 virus could not compete in fitness with wild type subpopulations without oseltamivir drug pressure, and thus has no potential to circulate among wild birds. The results of this study contrast to previous observations of drug induced resistance in an avian H1N1 virus, which was maintained also without drug exposure in Mallards. Experimental observations on persistence of NAI resistance in avian IAVs resemble NAI resistance seen in human IAVs, in which resistant N2 subtypes do not circulate, while N1 subtypes with permissive mutations can circulate without drug pressure. We speculate that the phylogenetic group N1 NAs may easier compensate for NAI resistance than group N2 NAs, though further studies are needed to confirm such conclusions.
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