Biology subjects

Gupta, J.

Publications and source records attributed to Gupta, J..

4 recordsLinked to original sources

bioRxiv2022

Elucidating Mechanisms of Tolerance to Salmonella Typhimurium Across Long-Term Infections Using the Collaborative Cross

Understanding the molecular mechanisms underlying resistance and tolerance to pathogen infection may present the opportunity to develop novel interventions. Resistance is the absence of clinical disease with low pathogen burden, while tolerance is minimal clinical disease in the face of high pathogen burden. Salmonella is a worldwide health concern. We studied 18 strains of Collaborative Cross mice that survive acute Salmonella Typhimurium (STm) infections. We infected these strains orally and monitored them for three weeks post-infection. Five strains cleared STm by the end of the experiment (resistant), while 6 strains maintained a bacterial load and survived to the end of the experiment (tolerant). The remaining 7 strains survived longer than 7 days but succumbed to infection before the end of the study period and were called "delayed susceptible" to differentiate them from strains that do not survive to day 7 (susceptible). Tolerant strains were colonized in Peyers patches, mesenteric lymph node, spleen and liver, while resistant strains had significantly reduced bacterial colonization. Tolerant strains had lower pre-infection core body temperatures than both delayed susceptible and resistant strains and had disrupted circadian patterns of body temperature post-infection sooner than resistant strains. Tolerant strains had higher circulating total white blood cells than resistant strains, driven by increased numbers of neutrophils. Tolerant strains had more severe tissue damage and higher circulating levels of MCP-1 and IFN-{gamma}, but lower levels of ENA-78 than resistant strains. QTL analysis revealed 1 significant association and 6 suggestive associations. RNA-seq analysis identified 22 genes that are differentially regulated in tolerant versus resistant animals that overlapped with the QTLs we identified and allowed us to identify the top 5 canonical pathways. Fibrinogen genes (Fga, Fgb, and Fgg) were found across the QTL, RNA, and top canonical pathways making them the best candidate genes for differentiating tolerance and resistance. Author SummaryAn infected host can respond in multiple ways to bacterial infection including resistance and tolerance. Resistance is a decrease in pathogen load, while in tolerance mild clinical signs are present despite high pathogen load. We infected a collection of 18 strains of genetically diverse mice with Salmonella Typhimurium for up to three weeks. Five strains were resistant, 6 strains were tolerant, and the remaining 7 strains survived an intermediate amount of time ("delayed susceptible"). Tolerant strains maintained bacterial load across several organs, while resistant strains reduced bacterial load. Tolerant strains had the lowest pre-infection core body temperatures and the most rapid disruption in circadian patterns of body temperature post-infection. Tolerant strains had higher circulating neutrophils, higher circulating levels of MCP-1 and IFN-{gamma}, but lower levels of ENA-78 than resistant strains, in addition to more severe tissue damage than resistant strains. QTL analysis revealed multiple associated regions, and gene expression analysis identified 22 genes that are differentially regulated in tolerant versus resistant animals in these regions. Fibrinogen genes (Fga, Fgb, and Fgg) were found across the QTL, RNA, and top canonical pathways making them the best candidate genes for differentiating tolerance and resistance.

genetics↗

bioRxiv2022

Genetic background influences survival of infections with Salmonella enterica serovar Typhimurium in the Collaborative Cross

Salmonella infections typically cause self-limiting gastroenteritis, but in some individuals these bacteria can spread systemically and cause disseminated disease. Salmonella Typhimurium (STm), which causes severe systemic disease in most inbred mice, has been used as a model for disseminated disease. To screen for new infection phenotypes across a range of host genetics, we orally infected 32 Collaborative Cross (CC) mouse strains with STm and monitored their disease progression for seven days by telemetry. Our data revealed a broad range of phenotypes across CC strains in many parameters including survival, bacterial colonization, tissue damage, complete blood counts (CBC), and serum cytokines. Eighteen CC strains survived to day 7, while fourteen susceptible strains succumbed to infection before day 7. Several CC strains had sex differences in survival and colonization. Surviving strains had lower pre-infection baseline temperatures and were less active during their daily active period. Core body temperature disruptions were detected earlier after STm infection than activity disruptions, making temperature a better detector of illness. All CC strains had STm in spleen and liver, but susceptible strains were more highly colonized. Tissue damage was weakly negatively correlated to survival. We identified loci associated with survival on Chromosomes (Chr) 1, 2, 4, 7. Polymorphisms in Ncf2 and Slc11a1, known to reduce survival in mice after STm infections, are located in the Chr 1 interval, and the Chr 7 association overlaps with a previously identified QTL peak called Ses2. We identified two new genetic regions on Chr 2 and 4 associated with susceptibility to STm infection. Our data reveal the diversity of responses to STm infection across a range of host genetics and identified new candidate regions for survival of STm infection. Author SummarySalmonella Typhimurium (STm) infections typically cause self-limiting diarrheal symptoms, but in some individuals, the bacteria can spread throughout the body and cause life-threatening infection. We used a population of genetically different mice (Collaborative Cross) to identify their range of responses to STm infection. We identified a broad range of outcomes across these different mice, including a group of mice susceptible to lethal infection and a group that survived our 7 day study. We found that mice that survived STm infection had a cooler core body temperature before infection than susceptible mice, while remaining active. Thus, body temperature, rather than activity, appears to be a better predictor of poor outcomes after STm infection. We identified several regions of the mouse genome that are associated with outcome after STm infection. One of these regions, mouse Chromosome (Chr) 1 has genes that are already known to influence susceptibility to STm infection. Two other regions that we identified to influence survival after STm infection, located on mouse Chr 2 and 4, are novel and contain numerous genes of interest that may be linked to susceptibility. Our work defines the utility of exploring how host genetic diversity influences infection outcomes with bacterial pathogens.

genetics↗

bioRxiv2022

Dopamine transporter and synaptic vesicle sorting defects initiate auxilin-linked Parkinson's disease

Auxilin participates in the uncoating of clathrin-coated vesicles (CCVs), thereby facilitating synaptic vesicle (SV) regeneration at presynaptic sites. Auxilin (DNAJC6/PARK19) loss-of- function mutations cause early-onset Parkinsons disease (PD). Here, we utilized auxilin-knockout (KO) mice to elucidate the mechanisms through which auxilin deficiency and clathrin-uncoating deficits lead to PD. We demonstrate that auxilin KO mice display the cardinal features of PD, including progressive motor deficits, -synuclein pathology, nigral dopaminergic loss, and neuroinflammation. Through unbiased proteomic and neurochemical analyses, we demonstrate that dopamine homeostasis is disrupted in auxilin KO brains, including via slower dopamine reuptake kinetics in vivo, an effect associated with dopamine transporter misrouting into axonal membrane deformities in the dorsal striatum. We also show that elevated macroautophagy and defective SV protein sorting contribute to ineffective dopamine sequestration and homeostasis, ultimately leading to neurodegeneration. This study advances our knowledge of how presynaptic endocytosis deficits lead to dopaminergic vulnerability and pathogenesis of PD.

neuroscience↗

bioRxiv2020

Sub-second heat inactivation of coronavirus

Heat treatment denatures viral proteins that comprise the virion, making virus incapable of infecting a host. Coronavirus (CoV) virions contain single-stranded RNA genomes with a lipid envelope and 4 proteins, 3 of which are associated with the lipid envelope and thus are thought to be easily denatured by heat or surfactant-type chemicals. Prior studies have shown that a temperature of as low as 75 {degrees}C and treatment duration of 15 min can effectively inactivate CoV. The applicability of a CoV heat inactivation method greatly depends on the length of time of a heat treatment and the temperature needed to inactivate the virus. With the goal of finding conditions where sub-second heat exposure of CoV can sufficiently inactivate CoV, we designed and developed a simple system that can measure sub-second heat inactivation of CoV. The system is composed of capillary stainless-steel tubing immersed in a temperature-controlled oil bath followed by an ice bath, through which virus solution can be flowed at various speeds. Flowing virus solution at different speeds, along with a real-time temperature monitoring system, allows the virus to be accurately exposed to a desired temperature for various durations of time. Using mouse hepatitis virus (MHV), a beta-coronavirus, as a model system, we identified that 85.2 {degrees}C for 0.48 s exposure is sufficient to obtain > 5 Log10 reduction in viral titer (starting titer: 5 x 107 PFU/mL), and that when exposed to 83.4 {degrees}C for 0.95 s, the virus was completely inactivated (zero titer, > 6 Log10 reduction). IMPORTANCEThree coronaviruses (CoVs) have now caused global outbreaks within the past 20 years, with the COVID19 pandemic caused by SARS-CoV-2 still ongoing. Methods that can rapidly inactivate viruses, especially CoVs, can play critical roles in ensuring public safety and safeguarding personal health. Heat treatment of viruses to inactive them can be an efficient and inexpensive method, with the potential to be incorporated into various human-occupied spaces. In this work, a simple system that can heat-treat viruses for extremely short period was developed and utilized to show that sub-second exposure of CoV to heat is sufficient to inactivate CoV. This opens up the possibility of developing instruments and methods of disinfecting CoV in diverse settings, including rapid liquid disinfection and airborne virus disinfection. The developed method can also be broadly utilized to assess heat sensitivity of viruses other viral pathogens of interest and develop sub-second rapid heat inactivation approaches.

bioengineering↗