---
OA_place: publisher
_id: '13984'
abstract:
- lang: eng
text: "Social insects fight disease using their individual immune systems and the
cooperative\r\nsanitary behaviors of colony members. These social defenses are
well explored against\r\nexternally-infecting pathogens, but little is known about
defense strategies against\r\ninternally-infecting pathogens, such as viruses.
Viruses are ubiquitous and in the last decades\r\nit has become evident that also
many ant species harbor viruses. We present one of the first\r\nstudies addressing
transmission dynamics and collective disease defenses against viruses in\r\nants
on a mechanistic level. I successfully established an experimental ant host –
viral\r\npathogen system as a model for the defense strategies used by social
insects against internal\r\npathogen infections, as outlined in the third chapter.
In particular, we studied how garden ants\r\n(Lasius neglectus) defend themselves
and their colonies against the generalist insect virus\r\nCrPV (cricket paralysis
virus). We chose microinjections of virus directly into the ants’\r\nhemolymph
because it allowed us to use a defined exposure dose. Here we show that this is
a\r\ngood model system, as the virus is replicating and thus infecting the host.
The ants mount a\r\nclear individual immune response against the viral infection,
which is characterized by a\r\nspecific siRNA pattern, namely siRNAs mapping against
the viral genome with a peak of 21\r\nand 22 bp long fragments. The onset of this
immune response is consistent with the timeline\r\nof viral replication that starts
already within two days post injection. The disease manifests in\r\ndecreased
survival over a course of two to three weeks.\r\nRegarding group living, we find
that infected ants show a strong individual immune response,\r\nbut that their
course of disease is little affected by nestmate presence, as described in chapter\r\nfour.
Hence, we do not find social immunity in the context of viral infections in ants.\r\nNestmates,
however, can contract the virus. Using Drosophila S2R+ cells in culture, we\r\nshowed
that 94 % of the nestmates contract active virus within four days of social contact
to\r\nan infected individual. Virus is transmitted in low doses, thus not causing
disease\r\ntransmission within the colony. While virus can be transmitted during
short direct contacts,\r\nwe also assume transmission from deceased ants and show
that the nestmates’ immune\r\nsystem gets activated after contracting a low viral
dose. We find considerable potential for\r\nindirect transmission via the nest
space. Virus is shed to the nest, where it stays viable for one\r\nweek and is
also picked up by other ants. Apart from that, we want to underline the potential\r\nof
ant poison as antiviral agent. We determined that ant poison successfully inactivates
CrPV\r\nin vitro. However, we found no evidence for effective poison use to sanitize
the nest space.\r\nOn the other hand, local application of ant poison by oral
poison uptake, which is part of the\r\nants prophylactic behavioral repertoire,
probably contributes to keeping the gut of each\r\nindividual sanitized. We hypothesize
that oral poison uptake might be the reason why we did\r\nnot find viable virus
in the trophallactic fluid.\r\nThe fifth chapter encompasses preliminary data
on potential social immunization. However,\r\nour experiments do not confirm an
actual survival benefit for the nestmates upon pathogen\r\nchallenge under the
given experimental settings. Nevertheless, we do not want to rule out the\r\npossibility
for nestmate immunization, but rather emphasize that considering different\r\nexperimental
timelines and viral doses would provide a multitude of options for follow-up\r\nexperiments.\r\nIn
conclusion, we find that prophylactic individual behaviors, such as oral poison
uptake,\r\nmight play a role in preventing viral disease transmission. Compared
to colony defense\r\nagainst external pathogens, internal pathogen infections
require a stronger component of\r\nindividual physiological immunity than behavioral
social immunity, yet could still lead to\r\ncollective protection."
acknowledged_ssus:
- _id: LifeSc
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Anna
full_name: Franschitz, Anna
id: 480826C8-F248-11E8-B48F-1D18A9856A87
last_name: Franschitz
citation:
ama: Franschitz A. Individual and social immunity against viral infections in ants.
2023. doi:10.15479/at:ista:13984
apa: Franschitz, A. (2023). Individual and social immunity against viral infections
in ants. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:13984
chicago: Franschitz, Anna. “Individual and Social Immunity against Viral Infections
in Ants.” Institute of Science and Technology Austria, 2023. https://doi.org/10.15479/at:ista:13984.
ieee: A. Franschitz, “Individual and social immunity against viral infections in
ants,” Institute of Science and Technology Austria, 2023.
ista: Franschitz A. 2023. Individual and social immunity against viral infections
in ants. Institute of Science and Technology Austria.
mla: Franschitz, Anna. Individual and Social Immunity against Viral Infections
in Ants. Institute of Science and Technology Austria, 2023, doi:10.15479/at:ista:13984.
short: A. Franschitz, Individual and Social Immunity against Viral Infections in
Ants, Institute of Science and Technology Austria, 2023.
corr_author: '1'
date_created: 2023-08-08T15:33:29Z
date_published: 2023-08-08T00:00:00Z
date_updated: 2026-04-07T13:51:29Z
day: '08'
ddc:
- '570'
- '577'
degree_awarded: PhD
department:
- _id: GradSch
- _id: SyCr
doi: 10.15479/at:ista:13984
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language:
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month: '08'
oa: 1
oa_version: Published Version
page: '89'
publication_identifier:
isbn:
- 978-3-99078-034-3
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
status: public
supervisor:
- first_name: Sylvia
full_name: Cremer, Sylvia
id: 2F64EC8C-F248-11E8-B48F-1D18A9856A87
last_name: Cremer
orcid: 0000-0002-2193-3868
title: Individual and social immunity against viral infections in ants
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2023'
...