DOI: 10.5061/dryad.p8cz8w9pp
title: Horizontal transmission of a murine retrovirus is driven by males within semi-natural enclosures

description: 1. Transmission is a key component of a pathogen’s life history, but it is
 often difficult to obtain reliable ecological estimates of the dominant
 mode(s) of transmission and how host traits, such as sex, influence
 transmission dynamics. 2. Here, we have developed a robust system pairing
 the use of semi-natural populations of house mice (Mus musculus) with
 modern molecular viral titering approaches to evaluate the transmission
 dynamics of Friend Virus Complex (FVC).  3. Semi-natural
 populations were founded with female and male mice that were either
 ‘index’ (initially infected via intraperitoneal injection) or ‘contact’
 (uninfected at the start of experiment). Three experimental population
 designs were implemented: female index only, male index only, and both
 female and male index. 4. Utilizing these enclosures, we found male-male
 transmission to be the predominant mode of transmission, with low rates of
 horizontal female transmission and no evidence of vertical transmission.
 Additionally, contact males that became infected harbor higher titers than
 females, while suffering a similar amount of spleen enlargement; this,
 paired with a strong correlation between titer and spleen size in males,
 and no correlation in females, indicates FVC viral dynamics differ between
 the sexes. 5. Lastly, natural transmission may be an impediment to FVC
 replication as infected contact animals have a lower viral titer than
 index animals. These results illuminate the complex life history of murine
 leukemia viruses and demonstrate the important role of host sex on
 pathogen transmission dynamics.
description: Cage Spleen Mass and
 Titer
 Spleen mass in grams is used as a proxy
 for virulence of the pathogen in mice (each row is a mouse) of both sexes
 (Sex), while FMuLV proviral load is used to quantify viral fitness. SFFV
 Infection Status indicates the presence/absence of this viral particle.
 The
 raw FMuLV proviral load data provided was log transformed and multiplied
 by spleen mass in order to get viral-load-per-spleen measurements for most
 analyses. Furthermore, only log transformed proviral load data was used to
 generate correlations with spleen mass. For more information, please see
 methods in the manuscript.
 Enclosure Spleen Mass and
 Titer
 Spleen mass and FMuLV titer are provided
 for mice (each row is a mouse) of both sexes (Sex), from seven independent
 populations (Population). Mice had initial infection statuses of either
 “contact” or “index”, and were incorporated into three population designs
 (female only index, male only index, or female and male index). SFFV
 Infection Status indicates the presence/absence of this viral particle.
 The raw FMuLV proviral load data provided was log transformed and
 multiplied by spleen mass in order to get viral-load-per-spleen
 measurements for most analyses. Furthermore, only log transformed proviral
 load data was used to generate correlations with spleen mass. For more
 information, please see methods in the
 manuscript.  
 FVC Transmission
 Dynamics The count of contact
 mice, by sex, that were either infected or uninfected at the termination
 of the study from seven populations representing three population designs
 (female only index, male only index, or female and male index). Both viral
 genomes (FMuLV and SFFV) are represented in Virus column.