Lack of evidence for trans-generational immune priming against the honey bee pathogen Melissococcus plutonius

Abstract

Trans-generational immune priming involves the transfer of immunological experience, acquired by the parents after exposure to pathogens, to protect their progeny against infections by these pathogens. Such natural mechanisms could be exploited to prevent disease expression in economically important insects, such as the honey bee. This mechanism occurs when honey bee queens are exposed to the pathogenic bacterium Paenibacillus larvae. Here, we tested whether natural or experimental exposure to Melissococcus plutonius—another bacterium triggering a disease in honey bee larvae—reduced the susceptibility of the queen’s progeny to infection by this pathogen. Because the immunological response upon pathogen exposure can lead to fitness costs, we also determined whether experimental exposure of the queens affected them or their colony negatively. Neither natural nor experimental exposure induced protection in the honey bee larvae against the deleterious effects of M. plutonius. Our results provided no evidence for the occurrence of trans-generational immune priming upon exposure of the queen to M. plutonius. Whether this lack was due to confounding genetic resistance, to unsuitable exposure procedure or to the absence of trans-generational immune priming against this pathogen in honey bees remains to be determined.

Novel eDNA approaches to monitor Western honey bee (Apis mellifera) microbial and arthropod communities

“…Some other bacterial findings include DNA from Gilliamella apicola , which has the ability to ferment sugar and inhabits areas in the honey bee directed toward the center of the lumen (Nowak et al, 2021), and gram negative Bombella apis , that inhabits the honey bee mid gut (Nowak et al, 2021). Interestingly enough, DNA from M. plutonius (European foulbrood), a honey bee pathogen that causes a severe larvae enteric disease, was also found (Forsgren, 2010; Ory et al, 2022). DNA from one fungi, Penicillium citrinum , known to have antimicrobial activity, was also found (Mazumder et al, 2002).…”

“…Interestingly enough, DNA from M. plutonius (European foulbrood), a honey bee pathogen that causes a severe larvae enteric disease, was also found (Forsgren, 2010;Ory et al, 2022). DNA from one fungi, Penicillium citrinum, known to have antimicrobial activity, was also found (Mazumder et al, 2002).…”

Differential resistance across paternal genotypes of honey bee brood to the pathogenic bacterium Melissococcus plutonius

“…We fed larvae within 2 h of transfer to the plastic cups with 10 μl of a diet containing the 2 × 10 5 M. plutonius CFU inoculum (Ory et al, 2022). We fed control individuals with 10 μl of the same diet, including saline suspension bacteria‐free buffer.…”

“…We fed control individuals with 10 μl of the same diet, including saline suspension bacteria‐free buffer. Changes in diet composition during the larval development have been described elsewhere (Ory et al, 2022). We prepared this diet with royal jelly from 10 healthy A. mellifera colonies, harvested under sterile conditions and stored at −25°C before use (Ory et al, 2022).…”

The oral vaccination with Paenibacillus larvae bacterin can decrease susceptibility to American Foulbrood infection in honey bees—A safety and efficacy study

“…The team used live, unattenuated Melissococcus plutonius delivered in a liquid sugar solution as a single dose directly to the queen. In this case, the authors could not show evidence for TGIP against M. plutonius (27). While this approach mimics the natural environment in hives and colonies where the queen is exposed to live pathogens, the approach still holds limitations for a broad adaption as the exposure of colonies to virulent pathogens holds a higher risk for accidental infection.…”