Samuel Jameson

Dr. Samuel Jameson

Tulane University, New Orleans, Louisiana, USA
orcid

Research Focus & Metrics

Academic Career Length

14Years (2013-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 October 2015 in PLOS Pathogens
Verified
Journal Article
Open access
PDF file
Berlin Londono-RenteriaBerlin Londono-Renteria
Berlin Londono-Renteria
ATAndrea Troupin
Andrea Troupin
MCMichael J Conway
Michael J Conway
DVDiana Vesely
Diana Vesely
MLMichael Ledizet
Michael Ledizet
TCTonya Colpitts
Tonya Colpitts
Dengue virus (DENV) is a mosquito-borne flavivirus that causes serious human disease and mortality worldwide. There is no specific antiviral therapy or vaccine for DENV infection. Alterations in gene expression during DENV infection of the mosquito and the impact of these changes on virus infection are important events to investigate in hopes of creating new treatments and vaccines. We previously identified 203 genes that were ≥5-fold differentially upregulated during flavivirus infection of the mosquito. Here, we examined the impact of silencing 100 of the most highly upregulated gene targets on DENV infection in its mosquito vector. We identified 20 genes that reduced DENV infection by at least 60% when silenced. We focused on one gene, a putative cysteine rich venom protein (SeqID AAEL000379; CRVP379), whose silencing significantly reduced DENV infection in Aedes aegypti cells. Here, we examine the requirement for CRVP379 during DENV infection of the mosquito and investigate the mechanisms surrounding this phenomenon. We also show that blocking CRVP379 protein with either RNAi or specific antisera inhibits DENV infection in Aedes aegypti. This work identifies a novel mosquito gene target for controlling DENV infection in mosquitoes that may also be used to develop broad preventative and therapeutic measures for multiple flaviviruses. Dengue virus (DENV) is responsible for serious human disease worldwide and the World Health Organization estimates that over 2 billion people are at risk for disease. There are no vaccines or specific antiviral medications currently available for DENV infection. DENV is transmitted to humans by infected mosquitoes during feeding and probing. By examining the effects of virus infection on gene expression, and interactions between virus and vector, we may be able to find new targets for prevention and treatment. Here we look at a mosquito protein, CRVP379, whose gene expression was highly increased during DENV infection in mosquitoes. We show a requirement for CRVP379 during DENV infection in the mosquito and a correlation between the levels of CRVP379 and levels of infection. Our results indicate that the protein may be acting with a putative DENV receptor in the mosquito, prohibitin protein. These data also suggest that blocking CRVP379 function may be used to block DENV infection in the mosquito.

24 February 2015 in Parasites & Vectors
Verified
Journal Article
Open access
PDF file
CHClaudia Herrera
Claudia Herrera
MLMeredith H Licon
Meredith H Licon
CNCatherine S Nation
Catherine S Nation
SJSamuel Jameson
Samuel Jameson
DWDawn Wesson
Dawn Wesson
Chagas disease is an anthropozoonosis caused by the protozoan parasite Trypanosoma cruzi that represents a major public health problem in Latin America. Although the United States is defined as non-endemic for Chagas disease due to the rarity of human cases, the presence of T. cruzi has now been amply demonstrated as enzootic in different regions of the south of the country from Georgia to California. In southeastern Louisiana, a high T. cruzi infection rate has been demonstrated in Triatoma sanguisuga, the local vector in this area. However, little is known about the role of small mammals in the wild and peridomestic transmission cycles. This study focused on the molecular identification and genotyping of T. cruzi in both small rodents and T. sanguisuga from a rural area of New Orleans, Louisiana. DNA extractions were prepared from rodent heart, liver, spleen and skeletal muscle tissues and from cultures established from vector feces. T. cruzi infection was determined by standard PCR using primers specific for the minicircle variable region of the kinetoplastid DNA (kDNA) and the highly repetitive genomic satellite DNA (satDNA). Genotyping of discrete typing units (DTUs) was performed by amplification of mini-exon and 18S and 24Sα rRNA genes and subsequent sequence analysis. The DTUs TcI, TcIV and, for the first time, TcII, were identified in tissues of mice and rats naturally infected with T. cruzi captured in an area of New Orleans, close to the house where the first human case of Chagas disease was reported in Louisiana. The T. cruzi infection rate in 59 captured rodents was 76%. The frequencies of the detected DTUs in such mammals were TcI 82%, TcII 22% and TcIV 9%; 13% of all infections contained more than one DTU. Our results indicate a probable presence of a considerably greater diversity in T. cruzi DTUs circulating in the southeastern United States than previously reported. Understanding T. cruzi transmission dynamics in sylvatic and peridomestic cycles in mammals and insect vectors will be crucial to estimating the risk of local, vector-borne transmission of T. cruzi to humans in the United States.

10 June 2019 in JMIR Research Protocols
Verified
Journal Article
Open access
ASAaron J Siegler
Aaron J Siegler
JBJames B Brock
James B Brock
CHChristopher B Hurt
Christopher B Hurt
LALauren Ahlschlager
Lauren Ahlschlager
KDKaren Dominguez
Karen Dominguez
LMLeandro A Mena
Leandro A Mena
Pre-exposure prophylaxis (PrEP) is highly efficacious for preventing HIV but has not yet been brought to scale among at-risk persons. In several clinical trials in urban areas, technology-based interventions have shown a positive impact on PrEP adherence. In rural and small-town areas in the United States, which often do not have geographically proximal access to PrEP providers, additional support may be needed. This may be particularly true for younger persons who are more likely to face multiple barriers to accessing PrEP services. Home-based care, accomplished through a tailored mobile phone app, specimen self-collection (SSC), and interactive video consultations, could increase both PrEP initiation and persistence in care. The goal of this study is to assess the initiation and persistence in PrEP care for those randomized to a home-care intervention (electronic PrEP, ePrEP) relative to those assigned to the standard of care (control) condition. We will conduct additional assessments, including quantitative and qualitative analyses, to contextualize trial results and facilitate scale-up. This 2-arm, randomized controlled trial will enroll young men who have sex with men (YMSM) aged between 18 and 24 years from rural areas of Georgia, Mississippi, and North Carolina. The trial will seek to recruit a diverse sample, targeting 50% participation among highly impacted groups of black or Latino men who have sex with men. Intervention participants will receive a study app that incorporates a messaging platform, a scheduling and milestone-based tracking system for PrEP care progress, electronic behavioral surveys, and interactive video consultations with a clinician. Complemented by SSC kits mailed to laboratories for standard PrEP-related monitoring, the ePrEP system will allow participants to access PrEP care without leaving their homes. YMSM randomized to the control condition will receive a listing of nearest local PrEP providers to receive standard PrEP care. Both groups will complete quarterly electronic surveys. The primary outcome, assessed at 6 and 12 months after randomization, will be the difference in the proportion of intervention versus control participants that achieve protective levels of the active metabolite of oral PrEP (tenofovir diphosphate in dried blood spots). Enrollment will begin in May 2019, with study completion in 2022. This trial will determine whether home PrEP care provided through an app-based platform is an efficacious means of expanding access to PrEP care for a diverse group of YMSM in rural and small-town areas of the United States. ClinicalTrials.gov NCT03729570; https://clinicaltrials.gov/ct2/show/NCT03729570 (Archived by WebCite at http://www.webcitation.org/78RE2Qizf). PRR1-10.2196/13982.

8 July 2015 in The American Journal of Tropical Medicine and Hygiene
Verified
Journal Article
Closed access
JRJoshua B. Richardson
Joshua B. Richardson
SJSamuel Jameson
Samuel Jameson
AGAndrea Gloria-Soria
Andrea Gloria-Soria
DWDawn Wesson
Dawn Wesson
JPJeffrey Powell
Jeffrey Powell
The mosquito Aedes aegypti is a vector of yellow fever, dengue, and chikungunya. Control of the insect is crucial to stop the spread of dengue and chikungunya, so it is critically important to understand its mating behavior. Primarily, based on laboratory behavior, it has long been assumed that Ae. aegypti females mate once in their lifetime. However, multiple inseminations have been observed in semi-field and laboratory settings, and in closely related species. Here, we report the first evidence of polyandry in a natural population of Ae. aegypti. Female Ae. aegypti were captured around the New Orleans, LA, metropolitan area. They were offered a blood meal and allowed to lay eggs, which were reared to the third-instar larval stage. A parentage analysis using four microsatellite loci was performed. Out of 48 families, 3 showed evidence of multiple paternity. An expanded analysis of these three families found that one family group included offspring contributed by three fathers, and the other two included offspring from two fathers. This result establishes that polyandry can occur in a small proportion of Ae. aegypti females in a natural setting. This could complicate future genetic control efforts and has implications for sampling for population genetics.

1 September 2016 in Biochimica et Biophysica Acta (BBA) - General Subjects
Verified
Journal Article
Open access
ATAndrea Troupin
Andrea Troupin
Berlin Londono-RenteriaBerlin Londono-Renteria
Berlin Londono-Renteria
MCMichael J. Conway
Michael J. Conway
ECErin Cloherty
Erin Cloherty
SJSamuel Jameson
Samuel Jameson
TCTonya Colpitts
Tonya Colpitts
Dengue virus (DENV) is a mosquito-borne flavivirus that causes significant human disease and mortality in the tropics and subtropics. By examining the effects of virus infection on gene expression, and interactions between virus and vector, new targets for prevention of infection and novel treatments may be identified in mosquitoes. We previously performed a microarray analysis of the Aedes aegypti transcriptome during infection with DENV and found that mosquito ubiquitin protein Ub3881 (AAEL003881) was specifically and highly down-regulated. Ubiquitin proteins have multiple functions in insects, including marking proteins for proteasomal degradation, regulating apoptosis and mediating innate immune signaling. We used qRT-PCR to quantify gene expression and infection, and RNAi to reduce Ub3881 expression. Mosquitoes were infected with DENV through blood feeding. We transfected DENV protein expression constructs to examine the effect of Ub3881 on protein degradation. We used site-directed mutagenesis and transfection to determine what amino acids are involved in Ub3881-mediated protein degradation. Immunofluorescence, Co-immunoprecipitation and Western blotting were used to examine protein interactions and co-localization. The overexpression of Ub3881, but not related ubiquitin proteins, decreased DENV infection in mosquito cells and live Ae. aegypti. The Ub3881 protein was demonstrated to be involved in DENV envelope protein degradation and reduce the number of infectious virions released. We conclude that Ub3881 has several antiviral functions in the mosquito, including specific viral protein degradation. Our data highlights Ub3881 as a target for future DENV prevention strategies in the mosquito transmission vector.

1 September 2014 in Journal of Medical Entomology
Verified
Journal Article
Open access
PDF file
RMRobin M. Moudy
Robin M. Moudy
SMSarah Michaels
Sarah Michaels
SJSamuel Jameson
Samuel Jameson
Berlin Londono-RenteriaBerlin Londono-Renteria
Berlin Londono-Renteria
VLVelma Lopez
Velma Lopez
DWDawn Wesson
Dawn Wesson
Although rare, there have been isolated reports of autochthonous transmission of Trypanosoma cruzi Chagas in the United States. In June 2006, a human