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Antiviral activity of extracts produced by isolated bacteria collected in termite mounds against important human and animal viruses

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Marina Aiello Padilla
Total Authors: 1
Document type: Doctoral Thesis
Institution: Universidade Estadual de Campinas, Instituto de Biologia
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Viral infections affect both humans and animals. Problems associated with a lack of vaccines and development of drug resistance stimulates the research for antiviral compounds. Bacteria are responsible for producing many compounds with important biological activities, so this study aimed to research for antiviral compounds produced by isolated associated bacteria. Extracts from different isolated termite associated bacteria were evaluated for in vitro antiviral activity against three important viruses to human and animal health: human herpesvirus type 1 (HHV-1), feline calicivirus (FCV) - surrogate model for human norovirus -and bovine viral diarrhea virus (BVDV) - surrogate model for hepatitis C virus. Of 90 extracts analyzed, 10% had percentage of inhibition (PI%) ? 98% against at least one virus: five were active against HHV-1, three showed activity against FCV and two were active against BVDV. Of the active species, six belong to Streptomyces genus, with one of them identified as S. chartreusis and four were identified as Achromobacter genus. Three extracts showed selectivity index (SI) above 3.5 against HHV-1, highlighting CDPA10 (Streptomyces sp) with SI = 17.10. Against the FCV and BVDV only two extracts were considered promising: LC22 (SI = 11.00), identified as Streptomyces sp and CDPA27 (S. chartreusis) with SI = 3.5, respectively. The extracts that stood out about the values of SI were also evaluated in a screening of mechanism of action. Of the three extracts with SI above 3.5 against HHV-1, only one showed antiviral activity in post-treatment, the others, including CDPA10 act as virus inactivation. The LC22, extract active against FCV, showed activity in the post-treatment as well as virus inactivation. Finally, the extract from S. chartreusis (CDPA27), acted in the post-treatment against BVDV. These three extracts CDPA10, LC22 and CDPA27 were then selected for fractionation on column C18 phase reverse with ascending order of methanol, resulting in six fractions. All fractions were evaluated against the respective virus and as a result was observed that the fraction 6 (100% methanol) were the most promising of the three extracts. That fraction of CDPA10 and CDPA27, active against HHV-1 and BVDV respectively, presented value of PI = 99%, while the fraction 6 of LC22 extract (active against FCV) presented PI = 90%. The SI evaluations of these promising fractions showed that the values increased substantially for both CDPA10 and CDPA27; however the fraction of LC22 extract had reduced SI value to 3.24. Finally, all extracts and their promising fractions were analyzed by gas chromatography-mass spectrometry (GC-MS). This analysis, when compared to the compounds already described in the NIST / 2005 library, it was not possible to identify them due to low similarity. More detailed studies should be performed to identify the bacterial species and their active compounds. The result of the present study provide new information for antiviral research using natural sources and demonstrates antiviral potential of compounds produced by termite associated bacteria (AU)

FAPESP's process: 11/08962-0 - Study of antiviral activity of extracts of bacteria isolated and identified from termite mounds
Grantee:Clarice Weis Arns
Support type: Regular Research Grants