Differences in acute phase response to bacterial, fungal and viral antigens in greater mouse-eared bats (Myotis myotis)

Abstract

The acute phase response (APR) is an evolutionarily well-conserved part of the innate immune defense against pathogens. However, recent studies in bats yielded surprisingly diverse results compared to previous APR studies on both vertebrate and invertebrate species. This is especially interesting due to the known role of bats as reservoirs for viruses and other intracellular pathogens, while being susceptible to extracellular microorganisms such as some bacteria and fungi. To better understand these discrepancies and the reservoir-competence of bats, we mimicked bacterial, viral and fungal infections in greater mouse-eared bats (Myotis myotis) and quantified different aspects of the APR over a two-day period. Individuals reacted most strongly to a viral (PolyI:C) and a bacterial (LPS) antigen, reflected by an increase of haptoglobin levels (LPS) and an increase of the neutrophil-to-lymphocyte-ratio (PolyI:C and LPS). We did not detect fever, leukocytosis, body mass loss, or a change in the overall functioning of the innate immunity upon challenge with any antigen. We add evidence that bats respond selectively with APR to specific pathogens and that the activation of different parts of the immune system is species-specific.

In sickness and in health: the dynamics of the fruit bat gut microbiota under a bacterial antigen challenge and its association with the immune response

“…In previous studies, bats (including R. aegyptiacus ) that received LPS exhibited elevated levels of the acute-phase protein, haptoglobin (see ( 27 )), suggesting that this protein plays a major role in antibacterial and antifungal defense in bats ( 31 – 33 ). Haptoglobin concentration was measured using the “PHASE” TM Haptoglobin Assay (Tridelta Development, Maynooth, Ireland) according to the manufacturer’s instructions, as done in other bat species ( 31 , 34 ).…”

“…We provoked an inflammatory response in bats using lipopolysaccharides (LPS), a component of the outer membrane in Gram-negative bacteria, that induces an acute phase response. LPS has previously been used to induce innate immune responses in R. aegyptiacus and other bat species, with species specific outcomes in term of fever, leukocytosis, body weight loss and elevated levels of the acute-phase proteins, haptoglobin and lysozyme (see ( 27 )). The inflammatory marker haptoglobin was measured and the GM of healthy (control) and immune challenged bats (henceforth, “challenged bats”) was analyzed before the administration of LPS and over a period of 48 hours in order to examine: 1) the diversity and structure of the bat GM following an immune challenge, 2) the associations between the immune response and shifts in the GM, 3) whether GM structure prior to the challenge affects the strength of the immune response and which specific bacterial taxa are responsible for this.…”

Combined effects of ambient temperature and food availability on induced innate immune response of a fruit-eating bat (Carollia perspicillata)

“…We collected *10 μl of blood from the propatagial vein 24 hours before and 24 hours after injections at around 06:00 pm and prepared two blood smears to estimate total white blood cell count and the neutrophil /lymphocyte ratio changes following Viola et al [44]. Total and differential white blood cell count in blood smears is the most common method used in bat studies that evaluate the acute phase response after LPS immune challenge [43,44,46,[52][53][54][55]. We assessed changes in total white blood cell count (WBC) and the neutrophil/lymphocyte ratio (N/L) after LPS immune challenge in relative terms as: ΔWBC = (WBC 24 hours after injection − WBC 24 hours before injection) / (WBC 24 hours before injection); and ΔN/L = (N/L 24 hours after injection − N/L 24 hours before injection) / (N/L 24 hours before injection).…”

Distribution of Acute Phase Proteins in Post-SARS CoV2 Mucormycosis Infection

“…Number of cases (%) Headache 14 (46.7) Facial pain/ swelling 6 (20) Blurring of vision 2 (6.7) Tooth pain 2 (6.7) Paresthesia 3 (10) Frozen section examination was performed in all the cases and revealed non or pauci-septated broad, ribbon like hyphae suggesting fungal elements and diagnosed as mucormycosis (Figure 1a & 1b).…”