BackgroundIn order to optimize net transmission success, parasites are hypothesized to evolve towards causing minimal damage to their reservoir host while obtaining high shedding rates. For many parasite species however this paradigm has not been tested, and conflicting results have been found regarding the effect of arenaviruses on their rodent host species. The rodent Mastomys natalensis is the natural reservoir host of several arenaviruses, including Lassa virus that is known to cause Lassa haemorrhagic fever in humans. Here, we examined the effect of three arenaviruses (Gairo, Morogoro and Lassa virus) on four parameters of wild-caught Mastomys natalensis: body mass, head-body length, sexual maturity and fertility. After correcting for the effect of age, we compared these parameters between arenavirus-positive (arenavirus RNA or antibody) and negative animals using data from different field studies in Guinea (Lassa virus) and Tanzania (Morogoro and Gairo viruses).ResultsAlthough the sample sizes of our studies (1297, 749 and 259 animals respectively) were large enough to statistically detect small differences in body conditions, we did not observe any adverse effects of these viruses on Mastomys natalensis. We did find that sexual maturity was significantly positively related with Lassa virus antibody presence until a certain age, and with Gairo virus antibody presence in general. Gairo virus antibody-positive animals were also significantly heavier and larger than antibody-free animals.ConclusionTogether, these results suggest that the pathogenicity of arenaviruses is not severe in M. natalensis, which is likely to be an adaptation of these viruses to optimize transmission success. They also suggest that sexual behaviour might increase the probability of M. natalensis to become infected with arenaviruses.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-2146-0) contains supplementary material, which is available to authorized users.
Aims: A novel β-coronavirus (2019-nCoV) has become a pandemic affecting hundreds of thousands of people worldwide. Since there is no effective treatment, the need of finding alternative methods which can help to curb this pandemic is urgent. This study aims to review the literature on the virucidal and cytotoxic properties of Aloe vera, one of the most studied plants considered as a nutraceutical in order to propose it as an alternative solution against COVID-19.
Methodology: The literature review was based mainly on the COVID-19 resources that have been made freely available to the scientific community but also on the usual databases such as Pubmed and Google scholar.
Results: The literature review shows that the plant has antiviral activity on several types of virus (Haemorrhagic Viral Rhobdavirus Septicaemia, Herpes simplex virus type 1, Herpes simplex virus type 2, Varicella-Zoster virus, human immunodeficiency virus, Influenza virus, poliovirus, Cytomegalovirus, Human papillomavirus) including coronavirus SARS-CoV-1. The plant is consumed orally in several forms and is safe. It is possible that molecules of this plant that have already shown effectiveness on other viruses by some mechanisms such as interaction of virus enzyme, breakdown of the viral envelope etc. could participate in the action of the plant. Also, the presence of minerals such as Zinc, which have shown an effect on SARS-CoV-1, could be involved in the antiviral effect of Aloe vera.
Conclusion: Molecular docking of the main molecules of Aloe vera with SARS-CoV-2 protease is in progress and clinical trials are necessary to confirm the activity of Aloe vera on COVID-19.
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