After absorbing research on manipulation of the human microbiome, the impact of waterway and agricultural microbiomes, antibiotic resistance spread and the potential of stewardship guard against it, and potential antimicrobial therapies of the future, we have yet to cover an important research theme seen in many sessions at ASM Microbe 2016: emerging infectious disease.
Many (though not all) of the microbes that present challenges in antimicrobial treatment are microbial species that have caused disease for generations. The other end of the spectrum involves microbes that are new or changing, and therefore effective therapies aren’t yet available. These will be covered as part of the final Special ASM Microbe Edition themed blog on emerging infectious viruses.
What Viruses Are out There
Monday morning began with an overview of several emerging infectious viruses. Stacey Schultz-Cherry discussed her work on avian influenza A virus (IAV). Her work investigating IAV genetic diversity shows that IAV infection of chickens is asymptomatic and generates genetic diversity, but IAV inoculation into ferrets leads to disease with genetic restriction. The fitness cost of additional mutations limits the ability of the virus to become transmissible between ferrets via aerosolized droplets, a transition that requires a known set of mutations. The virus tested, influenza A (H7N9), is mostly associated with infection of poultry workers exposed to infected birds, and the results may be useful in assessing risk of pandemic IAV. The goal of her molecular epidemiology studies is to someday predict phenotype from genotype (e.g., which circulating viruses will be most lethal), which is outside our current understanding of influenza virus pathogenesis.
Scott Weaver then updated epidemiology and management of chikungunya virus. Weaver identified the first report of Aedes aegypti transmission of the virus in the Americas, and has recently developed an improved diagnostic to determine seroprevalance using the Eilat virus to generate chikungunya virus antigens. His talk centered on vaccines as promising for the prevention of future chikungunya disease, but warned that vaccinating the right at-risk populations may prove challenging, due to similar symptomology as those suffering from dengue or Zika.
Sujan Shresta reviewed the influence of the host immune response to dengue, which can play a role in disease severity, particularly during secondary dengue virus infections of a different serotype. Any potential vaccine must protect all four serotypes, but researchers have yet to figure out how to generate protective antibody and T cell responses against all dengue virus types. Shresta presented her research on the adaptive cellular response, in which she has shown immunodominance changes during heterotypic infections, but that CD8+ T cells have an unusual role during reinfection: they can confer short-term protection during heterotypic reinfection but are dispensible for the robust protective immune response during homotypic reinfection. Teasing out the molecular basis for these different interactions is necessary for development of a dengue vaccine.
Pedro Vasconcelos then updated the most infamous flavivirus of the moment, Zika virus, based on his firsthand experience working in Brazil. Vasconcelos was part of the team whose whole-genome sequencing analysis suggest that a single introductory event in 2013 initiated the Brazilian Zika epidemic, and found the highest correlation of maternal Zika infection and subsequent encephaly during the 17th week of pregnancy.
Emerging viral infections were also discussed in a Saturday afternoon session. In addition to coverage of the above flaviviruses, Steven Oberste discussed emerging (and reemerging) picornaviruses. Oberste heads the group that developed advanced molecular diagnostics during the 2014 EV-D68 outbreak, and will discuss his work characterizing poliovirus vaccine responses ($) and designing novel vaccine platforms. Saturday’s session also saw Richard Hodinka summarize the importance of solid virology research programs (also an emphasis of our #ASMZika press conference participants), because the world is full of unpredictability. The source of the next viral epidemic may be from agriculture, water systems, or wildlife.
One certainty is that the next viral epidemic will not respect borders, as witnessed by recent outbreaks of Ebola, MERS-CoV, and Zika viruses. Emerging infectious disease is a global concern, and one that was addressed in a session on Friday afternoon. There, 9 presentations gave an overview of the most urgent infectious disease threats, with a list of topics that should sound familiar to most readers: Japanese encephalitis virus, chikungunya virus, malaria, typhoid, avian influenza, Crimean-Congo hemorrhagic fever, dengue, Ebola, and MERS. The session began with an overview from Reynolds Salerno, who emphasized the risk of emerging infections to clinical lab personnel and the importance of proper biosafety. This was echoed by Katelyn Jelden, who voiced concern for local West African clinical capabilities to support treatment centers, for whom she has provided biosafety protocols during the Ebola epidemic. These speakers served as reminders that risk is often disproportionate to health care workers during disease outbreaks.
How To Prepare, Prevent, and Treat These Diseases
Fortunately, basic and clinical researchers are hard at work to address the risks posed to health care workers and the general population from these diseases. Erica Ollmann Saphire’s research on filovirus protein structure led to a rapid antigen test used during the Ebola outbreak. For more details, you can listen to Ollmann Saphire discuss her work, as well as her decision not to work on Zika virus infection, on the TWiV podcast that was recorded during ASM Microbe.
The Zika virus outbreak is so recent that there is still much to understand about its molecular pathogenesis before direct applications for human health can be developed. Omar Bagasra presented work toward this understanding of pathogenesis, concentrating on 12 genes known to be associated with autosomal recessive primary microencephaly. Screening these genes for a role in Zika virus-mediated neural pathogenesis revealed four potential miRNAs with similar sequences to some of these genes; future work in his lab will concentrate on the role of these miRNAs during Zika virus infection.
ASM Microbe Minutes
Of course, our Dispatches series can’t fully encompass all the amazing sessions, lectures, and discussions covered at a meeting with over 11,000 participants! We used this series to highlight some major research themes, but you can go further in depth if you purchase the online sessions, available June 24th. These recordings offer you a chance to virtually attend ASM Microbe and hear the wonderful speakers for yourself.
Did you have a favorite session? How did the new ASM Microbe format suit your needs? Leave a comment below to let us know what you liked about ASM Microbe, or what areas need to be improved!