Biology subjects

Hesketh-Best, P. J.

Publications and source records attributed to Hesketh-Best, P. J..

3 recordsLinked to original sources

bioRxiv2025

The effect of two distinct viral-enriched inocula on the immune response and chemical cues in honey bee pupae

The combination of Varroa destructor (Varroa) and the viruses it vectors is a major driver of honey bee (Apis mellifera) colony losses. Hygienic behavior and individual immunity enable bees to cope with some pests and parasites. Hygienic response of adult bees is driven by olfactory cues emanating from diseased brood. In this study, we tested the effect of viral inoculation on the chemical profile and immune response of pupae, independently of Varroa. We injected pupae with various doses of an enriched inocula of either a deformed wing virus (DWV) B-A recombinant or Israeli acute paralysis virus (IAPV) and followed their development and survival for five days. At the end of the five-day period, volatile profiles, viral loads, and expression of seven immune genes were assessed. Both IAPV and the DWV loads increased to equivalent high levels irrespective of the initial dose applied. Notably, greater rates of mortality (60% loss) were observed with the highest IAPV dose when compared to the lowest IAPV dose (15% loss). The DWV inoculum, caused limited mortality but nonetheless inhibited pupae development. The IAPV injected pupae showed evidence of a dose dependent DWV amplification from either a DWV variant in the original IAPV inoculum or from an endogenous source of DWV in the pupae themselves. IAPV-injected pupae had lower expression of immune genes than DWV-injected pupae, suggesting IAPV inhibits the pupae immune response. Overall, among the seven tested immune genes six were upregulated with only vago downregulated, suggesting inhibition of the RNAi pathway following infection. Chemical cues of mock and untreated pupae were similar, but notably different from the virus-injected pupae for both inocula. Our findings show that Varroa-independent virus inoculated pupae produce unique virus-specific chemical cues; the ultimate consequence of such a change might lead to virus specific bee behavioral responses. Authors summaryThis study investigated how two major honey bee viruses, Deformed Wing Virus (DWV) and Israeli Acute Paralysis Virus (IAPV), affect pupae independent of the Varroa mite, which typically spreads them. This study was conducted in the laboratory on incubated pupae isolated from the colony and injected with two viral preparations (inocula). We tested the impact after five-days incubation. The results show that both viruses reach high levels in pupae, though IAPV inoculum proved far more deadly (up to 60% mortality) and appeared to suppress the pupaes immune response, possibly even amplifying co-occurring DWV. While less lethal, the DWV inoculum still inhibited normal development. Interestigly, the virus-infected pupae produced distinct, virus-specific chemical cues--unique volatile profiles different from healthy controls. Since adult honey bees use olfactory cues to detect and remove diseased brood (hygienic behavior), these findings suggest that the viruses themselves generate the "scent of sickness," which could trigger colony-wide behavioral responses and offer a vital target for enhancing the bees natural defenses against these major drivers of colony loss. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/683288v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@18e6203org.highwire.dtl.DTLVardef@c4b6d5org.highwire.dtl.DTLVardef@bf6499org.highwire.dtl.DTLVardef@165b9d1_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2024

Sacbrood viruses and select Lake Sinai virus variants dominated Apis mellifera colonies symptomatic for European foulbrood

European foulbrood (EFB) is a prevalent disease of the European honey bee (Apis mellifera) in the US, which can lead to colony decline and collapse. The bacterial components of EFB are well studied, but the diversity of viral infections within infected colonies has not been explored. Here we use meta-transcriptomics sequencing of 12 honey bee hives, symptomatic (+) and asymptomatic (-) for EFB to explore viral infection associated with the disease. We identified 41 viral genomes, belonging to two families, with a predominant occurrence of 34 genomes observed in colonies with severe EFB. This is in contrast to fewer, and a complete absence of Dicistroviridae genomes, recovered from healthy colonies (7 genomes). Identified viruses included multiple lineages previously reported in honey bees, namely Lake Sinai virus, Deformed wing virus, Sacbrood virus, Black queen cell virus, and Israeli acute paralysis virus. We observed specific Lake Sinai virus clades associated exclusively with EFB+ or EFB-colonies, in addition to EFB-afflicted colonies that exhibited an increase in relative abundance of sacbrood viruses. Multivariant analyses highlighted that a combination of site and EFB disease status influenced RNA virome composition, while EFB status alone didnt significantly impact it, presenting a challenge for comparisons between colonies kept in different yards. These findings contribute to the understanding of viral dynamics in honey bee colonies compromised by EFB and underscore the need for future investigations to consider viral composition when investigating EFB. ImportanceThis study on the viromes of honey bee colonies affected by European foulbrood (EFB) sheds light on the dynamics of viral populations in bee colonies in the context of a prevalent bacterial brood disease. The identification of distinct Lake Sinai virus and Sacbrood virus clades associated with colonies with severe EFB suggests a potential connection between viral composition and disease status, emphasizing the need for further investigation into the role of viruses during EFB infection. The observed increase in sacbrood viruses during EFB infection implies a possible viral dysbiosis, with potential implications for honey bee brood health. These findings contribute valuable insights for apicultural practices, offering a foundation for future research aimed at understanding and mitigating the impact of bacterial and viral infection in commercial honey bee operations and the management of EFB.

molecular biology↗

bioRxiv2022

Genomics of viruses infecting green and purple sulfur bacteria in two euxinic lakes

Viral infections of marine bacteria modulate the rates of primary production and the cycling of organic and inorganic matter in the worlds oceans. Here, we investigated the hypothesis that viral infections influence the ecology of purple and green sulfur bacteria (PSB and GSB) in anoxic and sulfidic (euxinic) lakes, modern analogs of early Earth oceans. Over 200 high and medium quality viral contigs were identified in long-read metagenomes from the sediments and water column of Lime Blue and Poison Lake, respectively. We compared these sequences with 94 predicted prophages identified in the complete genomes of PSB (n = 213) and GSB (n = 33). Viral genomes carrying psbA, encoding the small subunit of photosystem II protein, were present in all three datasets (sediment, water column, and complete genomes). The ubiquity of these genes suggests that PSB and GSB viruses interfere with the light reactions of sulfur-oxidizing autotrophs in a process similar to viral modulation of photosynthesis in Cyanobacteria. Viruses predicted to infect PSB and GSB also encoded auxiliary metabolic genes involved in reductive sulfur assimilation as cysteine, a pathway not yet described in these sulfur bacteria, as well as genes involved in pigment production (crtF) and carbon fixation (CP12, zwf, PGD). These observations highlight the potential for viral modulation of metabolic markers used as proxies to interpret biogeochemical processes in early Earth oceans.

microbiology↗