DOI: 10.5061/dryad.pzgmsbcxv
title: Data from: Combining in vivo and in vitro approaches to better understand host-pathogen nutritional interactions

description: Nutrition often shapes the outcome of host-parasite interactions, however
 understanding the mechanisms by which this occurs is often confounded by
 the intimate nature of the association and by the fact that the host and
 parasite may compete for the same limiting nutrients. One way of
 disentangling this interaction is to combine in vivo and in vitro
 approaches. Here, we explore the role of host nutrition in determining the
 outcome of infections using a model insect-bacterium system: the cotton
 leafworm Spodoptera littoralis and the blood-borne bacterium Xenorhabdus
 nematophila. S. littoralis larvae were reared on one of a series of 20
 chemically-defined diets ranging in their protein:carbohydrate (P:C) ratio
 and caloric density. They were then challenged with either a fixed dose of
 X. nematophila cells (live or dead) or were sham-injected. Survivorship of
 larvae challenged with live bacterial cells was strongly dependent on the
 protein levels of the diet, with mortality being highest on low-protein
 diets. This trend was reflected in the bacterial growth rate in vivo,
 which peaked in larvae fed low-protein diets. To determine whether in vivo
 bacterial growth rates were driven by the direct effects of blood
 nutrients or by the indirect effects of the host immune response, we used
 20 synthetic haemolymphs (‘nutribloods’) that mimicked the nutritional
 content of host blood. In vitro bacterial growth rate was negatively
 impacted by the protein content of the nutribloods, replicating the
 patterns seen in vivo and suggesting that nutrient availability and not
 host immunity was driving the interaction. By comparing standardized
 bacterial growth rates in vivo and in vitro, we conclude that the outcome
 of this host-parasite interaction is largely driven by ‘bottom-up’ effects
 of nutrients on bacterial growth, rather than by ‘top-down’ effects of
 nutrients on host-mediated immune responses. The outcome of host-parasite
 interactions is typically assumed to be strongly determined by the host
 immune response. The direct effects of nutrition have been underexplored
 and may have broad consequences for host-parasite interactions across
 taxa.
description: # Combining in vivo and in vitro approaches to better understand
 host-pathogen nutritional interactions
 [https://doi.org/10.5061/dryad.pzgmsbcxv](https://doi.org/10.5061/dryad.pzgmsbcxv) ## Description of the data and file structure This was a lab-based study. The data were analysed using R. The datasets compare growth of Xenorhabdus bacteria in vivo (Spodoptera littoralis larvae) and in vitro (synthetic insect blood). ### Files and variables #### File: BacGro4\_archive.csv **Description:**  This file contains the data required to compare bacteriall growth in vitro versus in vivo (see Figure 4 of the paper) ##### Variables * Diet.no: Diet number: 1-20 * Plate: Microtitre plate number * Max.OD: Maximum optical density at 600 nm * P2C: Protein : Carbohydate (g) * P2C.ratio: Protein : Carbohydate (1:5 to 5:1) * Conc: Concentration of the digestible diet * prop.Prot.x: Proportion of protein in diet (P/P+C) * pc.Prot: Percentage of protein in diet (P/P+C) (%) * pc.Carb: Percentage of carbohydrate in diet (P/P+C) (%) * pc.cellulose: Percentage of indigesticle cellulose in diet (%) * Total.prot.g: Absolute amount of protein in the diet (g/100g) * Total.carb.g: Absolute amount of carbohydrate in the diet (g/100g) * cellulose.g: Absolute amount of cellulose in the diet (g/100g) * Total.g.per.diet: Total g of diet per 100g * Protein: Amount of protein in the nutriblood (mg/mL) * Sum.carbs: Amount of carbohydrate in the nutribloood (mg/mL) * Lipids: Amount of lipids in the nutribloood (mg/mL) * stvitroP: Standardized protein in the nutriblood * stvitroC: Standardized carbohydrate in the nutriblood * stvitrogro: Standardized bacterial growth in the nutriblood * stvivoP: Standardized protein in the diet * stvivoC: Standardized carbohydrate in the diet * stvivoMaxOD: Standardized bacterial growth in vivo * stvitrovivoP: Standardized difference in protein in vitro versus in vivo * stvitrovivoC: Standardized difference in carbohydrate in vitro versus in vivo * stDIFF: Standardized difference in bacterial growth in vitro versus in vivo #### File: BFdata\_archive.csv **Description:** This file contains the data to compare speed of death and bacterial growth rate in relation to dietary attributes (see Figures 1- 3 of paper). ##### Variables * Diet.no: Diet number: 1-20 * ID: Arbitrary Caterpilar number * Treat: Treatment: Dead, sham or live challenged * DState: Stage at death (caterpillar, pupae, moth) * F1D3.ml.mean: Mean number of Xenorhabdus F1D3 colony forming units/ml * P2C: Protein : Carbohydrate (g) * P2C.ratio: Protein : Carbohydate (g) * Conc: Concentration of the digestible diet * prop.Prot: Proportion of protein in diet (P/P+C) * pc.Prot: Percentage of protein in diet (P/P+C) (%) * pc.Carb: Percentage of carbohydrate in diet (P/P+C) (%) * pc.cellulose: Percentage of indigesticle cellulose in diet (%) * Total.prot.g:  Absolute amount of protein in the diet (g/100g) * Total.carb.g: Absolute amount of carbohydrate in the diet (g/100g) * cellulose.g: Absolute amount of cellulose in the diet (g/100g) * Total.g.per.diet: Total g of diet per 100g * Died: Died during larval stage (0=no, 1=yes) * DSpeed: Time taken to die (h) * logF1D3mean: log10(mean number of Xenorhabdus F1D3 colony forming units+1) * Outcome: Outcome (Sham-injected, Dead bacteria-injected, Live-bacteria-injected survived, Live bacteria-injected died) * st.DSpeedALL: Standardized speed of death (all larvae) * st.F1D3mean: Standardized mean number of Xenorhabdus F1D3 colony forming units * st.DSpeed: Stadardized time taken to die * st.logF1D3mean: Standardized log10(mean number of Xenorhabdus F1D3 colony forming units+1) ## Code/software All files are .csv and can be read using Excel ## Access information Other publicly accessible locations of the data: * not applicable Data was derived from the following sources: * not applicable