bims-inflim 2018-04-22 papers

Issue of 2018–04–22
two papers selected by
Christine Oshansky-Weilnau

Rev Med Virol. 2018 Apr 15. e1976

A review on current status of antiviral siRNA.

Abid Qureshi, Vaqar Gani Tantray, Altaf Rehman Kirmani, Abdul Ghani Ahangar.

Viral diseases like influenza, AIDS, hepatitis, and Ebola cause severe epidemics worldwide. Along with their resistant strains, new pathogenic viruses continue to be discovered so creating an ongoing need for new antiviral treatments. RNA interference is a cellular gene-silencing phenomenon in which sequence-specific degradation of target mRNA is achieved by means of complementary short interfering RNA (siRNA) molecules. Short interfering RNA technology affords a potential tractable strategy to combat viral pathogenesis because siRNAs are specific, easy to design, and can be directed against multiple strains of a virus by targeting their conserved gene regions. In this review, we briefly summarize the current status of siRNA therapy for representative examples from different virus families. In addition, other aspects like their design, delivery, medical significance, bioinformatics resources, and limitations are also discussed.

Keywords: RNAi; antiviral; clinical trials; delivery; design; limitations; resources; siRNA; virus

DOI: https://doi.org/10.1002/rmv.1976

Math Biosci. 2018 Apr 11. pii: S0025-5564(18)30058-0. [Epub ahead of print]

Who is the infector? Epidemic models with symptomatic and asymptomatic cases.

Ka Yin Leung, Pieter Trapman, Tom Britton.

What role do asymptomatically infected individuals play in the transmission dynamics? There are many diseases, such as norovirus and influenza, where some infected hosts show symptoms of the disease while others are asymptomatically infected, i.e. do not show any symptoms. The current paper considers a class of epidemic models following an SEIR (Susceptible  →  Exposed  →  Infectious  →  Recovered) structure that allows for both symptomatic and asymptomatic cases. The following question is addressed: what fraction ρ of those individuals getting infected are infected by symptomatic (asymptomatic) cases? This is a more complicated question than the related question for the beginning of the epidemic: what fraction of the expected number of secondary cases of a typical newly infected individual, i.e. what fraction of the basic reproduction number R0, is caused by symptomatic individuals? The latter fraction only depends on the type-specific reproduction numbers, while the former fraction ρ also depends on timing and hence on the probabilistic distributions of latent and infectious periods of the two types (not only their means). Bounds on ρ are derived for the situation where these distributions (and even their means) are unknown. Special attention is given to the class of Markov models and the class of continuous-time Reed-Frost models as two classes of distribution functions for latent and infectious periods. We show how these two classes of models can exhibit very different behaviour.

Keywords: Markov models; continuous-time Reed-Frost models; final size; two-type SEIR epidemic; type of infector

DOI: https://doi.org/10.1016/j.mbs.2018.04.002