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Author: Donna Huber

CTEGD opens lab doors to undergraduates at area schools

Donna Huber on September 10, 2018

Sharon Keller and Makayla Yang

by Donna Huber

When UGA alumna Dr. Sharon Keller accepted the position of Assistant Professor at Georgia Gwinnett College (GGC) she wasn’t ready to say goodbye to the research project she started in graduate school. Since GGC is not a research-intensive institution, Keller approached her Ph.D. mentor Dr. Silvia Moreno, distinguished research professor in the department of cellular biology and member of the Center for Tropical and Emerging Global Diseases (CTEGD) at the University of Georgia, about continuing the project in her free time. It was during this conversation, that they came up with a way of not only keeping Keller in the lab but helping to solve a problem that many undergraduates in the biological sciences face – gaining independent research experience in an NIH-funded laboratory.

“The opportunity to be involved in a collaborative research project was very exciting and an experience that I knew would be attractive to GGC students who might be interested in this type of research,” said Keller.

In 2014, with matching support from Franklin College’s Office of the Dean, the Center for Tropical and Emerging Global Diseases sought to increase diversity in graduate education by offering independent research opportunities to faculty from local non-research intensive institutions. Originally, it was meant to be a 1-month summer sabbatical for these faculty. However, during her conversation with Keller, Moreno saw an opportunity to expand the program.

“Students get very excited when they experience independent research,” said Moreno. “But at some of the smaller schools in the area, they don’t have the opportunity to experience this level of research.”

Many undergraduate teaching labs consist of well-prepared protocols and information on the expected result. The experiments they conduct are supposed to work. That’s not how it happens in real life. In a research lab, a student develops a different skill set from those they learn in a teaching lab. They use critical thinking, problem-solving, and result analysis skills to tackle real-world problems.

“As an instructor, I see the disconnect students can have between a learned concept and the application of that concept,” said Keller.

Keller agreed it was a great idea to include her undergraduates and began the process of selecting students shortly after their initial conversation. Makayla Yang, a student lab assistant in the biology department at GGC, was one of two students selected to accompany Keller 2 – 4 times a week to the laboratory of Dr. Roberto Docampo, the Barbara and Sanford Orkin –GRA Eminent Scholar in Tropical and Emerging Global Diseases.

“Working with trypanosomes at UGA was one of the greatest learning opportunities I have experienced,” said Yang. “It made me see the bigger picture of my work that it was not just an undergraduate research opportunity, but it was a contribution to science and what could be a future health solution.”

It is the hope of the program that by giving faculty and undergraduates from area schools real-life research experience more students will apply to graduate school and have the same competitive edge as students from research-intensive institutions.

For Yang, the experience has her thinking more about pursuing research and a Ph.D.  “I was able to discover my true passion for lab bench work,” concluded Yang.

 

If you are a faculty member at a Georgia non-research intensive institution and are interested in participating in this program, please contact Silvia Moreno (moreno@uga.edu).

 

Your financial gift will help us expand this program, giving even more area undergraduates hands-on research experience.

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Young Adults in Endemic Areas: An Untreated Group in Need of School-Based Preventive Chemotherapy for Schistosomiasis Control and Elimination

Donna Huber on September 5, 2018

Abstract

Parasitologic surveys of young adults in college and university settings are not commonly done, even in areas known to be endemic for schistosomiasis and soil-transmitted helminths. We have done a survey of 291 students and staff at the Kisumu National Polytechnic in Kisumu, Kenya, using the stool microscopy Kato-Katz (KK) method and the urine point-of-care circulating cathodic antigen (POC-CCA) test. Based on three stools/two KK slides each, in the 208 participants for whom three consecutive stools were obtained, Schistosoma mansoni prevalence was 17.8%. When all 291 individuals were analyzed based on the first stool, as done by the national neglected tropical disease (NTD) program, and one urine POC-CCA assay (n = 276), the prevalence was 13.7% by KK and 23.2% by POC-CCA. Based on three stools, 2.5% of 208 participants had heavy S. mansoni infections (≥400 eggs/gram feces), with heavy S. mansoni infections making up 13.5% of the S. mansoni cases. The prevalence of the soil-transmitted helminths (STH: Ascaris lumbricoides, Trichuris trichiura and hookworm) by three stools was 1.4%, 3.1%, and 4.1%, respectively, and by the first stool was 1.4%, 2.4% and 1.4%, respectively. This prevalence and intensity of infection with S. mansoni in a college setting warrants mass drug administration with praziquantel. This population of young adults is ‘in school’ and is both approachable and worthy of inclusion in national schistosomiasis control and elimination programs.

Harrison K. Korir, Diana K. Riner, Emmy Kavere, Amos Omondi, Jasmine Landry, Nupur Kittur, Eric M. Ndombi, Bartholomew N. Ondigo, W. Evan Secor, Diana M. S. Karanja and Daniel G. Colley. 2018. Trop. Med. Infect. Dis.; 3(3):100. https://doi.org/10.3390/tropicalmed3030100

Antiplasmodial flavanones and a stilbene from Carpha glomerata

Donna Huber on September 4, 2018

graphical abstract

Abstract

Bioassay-guided fractionation of an extract of Carpha glomerata (Cyperaceae) led to the isolation of seven compounds. Compounds 1 (carphorin A), 3 (carphorin C), 4(carphorin D), and 5 (carphabene) are new compounds, and compound 2 (8-(3″-hydroxyisoamyl)-naringenin) was isolated for the first time as a natural product. All structures were elucidated based on analyses of their HR-ESIMS and 1D and 2D NMR data. Compounds 1, 2, and 6, which have prenyl or hydroxyprenyl side chains, exhibited antiplasmodial activities with IC50 values of 5.2 ± 0.6, 3.4 ± 0.4, and 6.7 ± 0.8 µM against the drug-resistant Dd2 strain of Plasmodium falciparum. In addition the prenylated stilbene 5 also showed good activity, with IC50 5.8 ± 0.7 µM.

Namki Cho, Ana Lisa Valenciano, Yongle Du, Jason Clement, Maria B. Cassera, Michael Goetz, David G. I. Kingston. 2018. Bioorganic & Medicinal Chemistry Letters; 28(20):3368-3371. https://doi.org/10.1016/j.bmcl.2018.09.003

Spatio-temporal spillover risk of yellow fever in Brazil

Donna Huber on August 29, 2018

Abstract

Background: Yellow fever virus is a mosquito-borne flavivirus that persists in an enzoonotic cycle in non-human primates (NHPs) in Brazil, causing disease in humans through spillover events. Yellow fever (YF) re-emerged in the early 2000s, spreading from the Amazon River basin towards the previously considered low-risk, southeastern region of the country. Previous methods mapping YF spillover risk do not incorporate the temporal dynamics and ecological context of the disease, and are therefore unable to predict seasonality in spatial risk across Brazil. We present the results of a bagged logistic regression predicting the propensity for YF spillover per municipality (administrative sub-district) in Brazil from environmental and demographic covariates aggregated by month. Ecological context was incorporated by creating National and Regional models of spillover dynamics, where the Regional model consisted of two separate models determined by the regions’ NHP reservoir species richness (high vs low).

Results: Of the 5560 municipalities, 82 reported YF cases from 2001 to 2013. Model accuracy was high for the National and low reservoir richness (LRR) models (AUC = 0.80), while the high reservoir richness (HRR) model accuracy was lower (AUC = 0.63). The National model predicted consistently high spillover risk in the Amazon, while the Regional model predicted strong seasonality in spillover risk. Within the Regional model, seasonality of spillover risk in the HRR region was asynchronous to the LRR region. However, the observed seasonality of spillover risk in the LRR Regional model mirrored the national model predictions.

Conclusions: The predicted risk of YF spillover varies with space and time. Seasonal trends differ between regions indicating, at times, spillover risk can be higher in the urban coastal regions than the Amazon River basin which is counterintuitive based on current YF risk maps. Understanding the spatio-temporal patterns of YF spillover risk could better inform allocation of public health services.

RajReni B. Kaul, Michelle V. Evans, Courtney C. Murdock and John M. Drake. 2018. Parasites & Vectors; 11:488. https://doi.org/10.1186/s13071-018-3063-6

Newly published study shows that temperature has effect on Zika transmission

Donna Huber on August 28, 2018

 

Zika was once thought of as a problem contained to tropical and sub-tropical parts of the world. Today we know better – with 3.9 billion people in 120 countries around the globe at risk of contracting some type of arboviral disease – Zika and related diseases like dengue and chikungunya are spreading, opening up the threat to more and more of the world’s population as our climate changes.

In a new study recently published in the Proceedings of the Royal Society B, researchers from the University of Georgia, Stanford University, Harvard University, and the University of Florida have found that temperature is a driving factor in the transmission of the Zika virus. The team, led by Dr. Courtney Murdock, an assistant professor of infectious disease and ecology at the University of Georgia College of Veterinary Medicine and Odum School of Ecology, and Blanka Tesla, a graduate student at UGA, measured the effect of temperature on the probability of transmission from an infectious mosquito to a human, how quickly the virus spreads throughout the mosquito’s body, allowing it to get into their saliva and become infectious, and areas in the world most suitable for Zika transmission.

They discovered that temperature had a strong effect on mosquito infection and survival traits, and that the least optimal temperatures for transmission were the highest and the lowest temperatures they tested. Thus, as temperatures edge upwards due to climate change, increasing urbanization, or with time of the year, the environmental suitability for Zika transmission should increase. This would result in an expansion of Zika further north and into longer seasons. In contrast, areas that are already permissive or near the thermal optimum for Zika transmission are predicted to experience a decrease in overall environmental suitability.

They then compared the Zika transmission model to one used to predict dengue. Here they discovered that Zika is transmitted more readily at warmer temperatures than dengue virus, which means that current estimates on the global environmental suitability for Zika transmission using dengue as a surrogate are vastly over-predicting its possible range.

“While there are certainly other factors that need to be examined when it comes to the transmission of Zika, this study established that temperature plays a very important role,” said Courtney Murdock assistant professor of infectious disease and ecology at the UGA College of Veterinary Medicine and Odum School of Ecology. “As climate change continues to evolve world-wide, this shows us that we need to keep a watchful eye on how rising temperatures impact the spread of these types of disease.”

The full article was published in the Proceedings of the Royal Society B on August 15, 2018.

 

This story was originally posted at the College of Veterinary Medicine on August 23, 2018.

 

 

 

 

Estimating the effects of variation in viremia on mosquito susceptibility, infectiousness, and R0 of Zika in Aedes aegypti

Donna Huber on August 22, 2018

Abstract

Zika virus (ZIKV) is an arbovirus primarily transmitted by Aedes mosquitoes. Like most viral infections, ZIKV viremia varies over several orders of magnitude, with unknown consequences for transmission. To determine the effect of viral concentration on ZIKV transmission risk, we exposed field-derived Ae. aegypti mosquitoes to four doses (103, 104, 105, 106 PFU/mL) representative of potential variation in the field. We demonstrate that increasing ZIKV dose in the blood-meal significantly increases the probability of mosquitoes becoming infected, and consequently disseminating virus and becoming infectious. Additionally, we observed significant interactions between dose and days post-infection on dissemination and overall transmission efficiency, suggesting that variation in ZIKV dose affects the rates of midgut escape and salivary gland invasion. We did not find significant effects of dose on mosquito mortality. We also demonstrate that detecting virus using RT-qPCR approaches rather than plaque assays potentially over-estimates key transmission parameters, including the time at which mosquitoes become infectious and viral burden. Finally, using these data to parameterize an R0 model, we showed that increasing viremia from 104 to 106 PFU/mL increased relative R0 3.8-fold, demonstrating that variation in viremia substantially affects transmission risk.

Blanka Tesla, Leah R. Demakovsky, Hannah S. Packiam, Erin A. Mordecai, Américo D. Rodríguez, Matthew H. Bonds, Melinda A. Brindley, Courtney C. Murdock. 2018. PLOS Neglected Tropical Diseases; 12(8): e0006733. https://doi.org/10.1371/journal.pntd.0006733

Temperature drives Zika virus transmission: evidence from empirical and mathematical models

Donna Huber on August 15, 2018

Abstract

Temperature is a strong driver of vector-borne disease transmission. Yet, for emerging arboviruses we lack fundamental knowledge on the relationship between transmission and temperature. Current models rely on the untested assumption that Zika virus responds similarly to dengue virus, potentially limiting our ability to accurately predict the spread of Zika. We conducted experiments to estimate the thermal performance of Zika virus (ZIKV) in field-derived Aedes aegypti across eight constant temperatures. We observed strong, unimodal effects of temperature on vector competence, extrinsic incubation period and mosquito survival. We used thermal responses of these traits to update an existing temperature-dependent model to infer temperature effects on ZIKV transmission. ZIKV transmission was optimized at 29°C, and had a thermal range of 22.7°C–34.7°C. Thus, as temperatures move towards the predicted thermal optimum (29°C) owing to climate change, urbanization or seasonality, Zika could expand north and into longer seasons. By contrast, areas that are near the thermal optimum were predicted to experience a decrease in overall environmental suitability. We also demonstrate that the predicted thermal minimum for Zika transmission is 5°C warmer than that of dengue, and current global estimates on the environmental suitability for Zika are greatly over-predicting its possible range.

Blanka Tesla, Leah R. Demakovsky, Erin A. Mordecai, Sadie J. Ryan, Matthew H. Bonds, Calistus N. Ngonghala, Melinda A. Brindley, and Courtney C. Murdock. 2018. Proceedings of the Royal Society B; 285(1884):0962-8452. https://doi.org/10.1098/rspb.2018.0795