A story of two viruses


Synopsis : New and previous honey bee viruses. Are these a trigger for concern in our bees, or for bees they share the atmosphere with? Details, suspicions, omissions and actuality.


A story of two bee viruses.

One new virus that you simply most likely haven’t heard about however is perhaps involved about as soon as you already know slightly extra … however most likely shouldn’t be.

And one other virus that you simply do learn about and which some non-beekeepers are involved about … however presumably shouldn’t be.

Worker bee with DWV symptoms

Employee bee with DWV signs

Inevitably that is going to contain a little bit of science, however I’ll try to limit it to the minimal wanted to get the message throughout.

Buckle up!

Virology 101

A virus is an obligate intracellular parasite.

They’re parasites as a result of they lack among the ‘equipment’ crucial for dwelling and reproducing, in order that they ‘steal’ these capabilities from one other organism – the host.

Intracellular as a result of they will solely steal these capabilities as soon as contained in the host … and never simply wandering round within the blood or the center, they need to be contained in the cells of the host.

Lastly, obligate as a result of that is the solely approach {that a} virus can replicate.

Replication is a virologists time period for replica. It means each making extra of and copying, as a result of the act of copy entails a single virus making tens, a whole lot or hundreds of copies of itself.

As a result of the virus replicates inside the host cells and steals among the capabilities of the cell to assist this course of, it can lead to cell harm or dying.

This will likely or might not harm the host.

A typical human incorporates about 30 trillion cells . The loss of some hundred or a whole lot of hundreds to virus replication might effectively go unnoticed. Nevertheless, if the cells are in a vital location – just like the mind – then the implications might be severe (or worse).

While you get a chilly the virus replicates in just a few thousand cells of your higher respiratory tract. The signs – headache, runny nostril, yearning for chocolate – are as a result of immune response, not as a result of direct mobile harm.

A bee is about 1/375,000th the load of a human which, professional rata, means they’ve about 80 million cells. Nonetheless numerous cells. Once more, the loss of some (or few thousand) on account of virus replication won’t be an issue.

Which is lucky as some viruses are at all times current …

Deformed wing virus

Until you reside in Australia, the place it’s not been detected, your bees are contaminated with deformed wing virus (DWV) . In a hive with well-managed Varroa ranges – both by the bees or the beekeeper – DWV quietly and unobtrusively replicates, apparently inflicting no harm to the host bee.

Some completely wholesome bees with DWV

Since all honey bees have DWV, even these with out Varroa, it’s crucial to incorporate the ’apparently’ within the earlier sentence. We are able to’t be sure that the bees don’t really feel garbage because it’s tough to make a significant comparability with bees that lack DWV.

Let’s assume they’re OK.

The virus replicates, it’s handed from bee to bee throughout trophallaxis, and vertically through eggs and sperm, from the queen/drone to the employees. Each bee carries just a few thousand replicating DWV virus particles. They’re unfold about when the bee defecates or when a forager visits a plant to gather pollen or nectar.

Inevitably because of this DWV is widespread within the atmosphere. In any case, honey bees are widespread and so they forage far away from their nest web site (the hive).

Inevitably this additionally signifies that some ecologists and environmental scientists are involved that the DWV left within the atmosphere by honey bees might infect different bees, such because the 24 bumble bee or ~225 solitary bee species we have now within the UK.

This can be a completely cheap concern.

Nevertheless, simply because DWV is current doesn’t imply it will possibly infect different bees or, if it does, that it’s going to replicate within the recipient or, if it does, that it’s going to trigger harm.

An evolutionary perspective

It’s value remembering that the Apis group of bees (which now contains the honey bee, Apis mellifera) diverged from different bees about 100 million years in the past.

Lego evolution parody

Evolution …

That time period is greater than ample to have produced enormous adjustments in look, anatomy and the intracellular atmosphere upon which viruses rely for replication.

100 million years is older than the earliest primate-like mammal. The Outdated World monkeys (from which people ultimately developed) break up about 35 million years in the past and the final frequent ancestor of people and chimpanzees existed about 8-9 million years in the past.

The evolution of termites, ants, wasps and bees

Simply because they’re known as bees doesn’t imply they give the impression of being or behave the identical … or that all of them share the mandatory intracellular options that may assist virus replication.

Some viruses replicate in a variety of host species – even evolutionarily divergent hosts – however others are very restricted of their host vary.


So, having offered some evolutionary caveats, let me return to the three factors I made above which are crucial for DWV (or different honey bee viruses) to be a menace to different bee species. These are:

  • is the virus infectious and might it infect?
  • can it replicate?
  • does it trigger harm?

The virus is infectious if it has the potential to copy after introduction to a bunch. However can it infect the host within the first place? Semantics, however important.

Let’s take care of whether or not virus within the atmosphere is infectious … that is really greatest answered utilizing honey bees. 

Maurizio Mazzei and colleagues demonstrated that infectious DWV could possibly be detected on pollen from flowers visited by honey bees (Mazzei et al., 2014). They did this by isolating DWV from pollen and injecting it into honey bees.

The bees turned contaminated (they may discriminate between the DWV already current and the injected virus genetically), confirming that the DWV within the atmosphere is – or no less than might be – infectious.

Replication and pathology (illness) in different species?

A few years in the past two bumble bees have been recognized with deformed wings. Delicate genetic evaluation demonstrated that DWV could possibly be detected in (or on?) these bees.

This was taken as proof that DWV causes deformed wings in bumble bees … 🙁 .

Proof for DWV an infection in bumble bees – click on picture for full legend.

Er, not so quick!

Simply because one thing is current doesn’t imply that it’s the causative agent of the signs … I’ll return up to now later.

Subsequent research have proven that, though DWV can replicate in bumble bees, there’s little proof that the virus causes deformed wings.

Or for that matter any overt signs (Gusachenko et al., 2020).

I’ve mentioned among the research that my lab printed beforehand and so received’t rehash them intimately right here.

Briefly, we both fed or injected bumble bees with DWV however might solely present replication after injection. We even fed full nests of bumble bees for a month – maintained within the laboratory – with enormous quantities of DWV and will detect no virus in staff, the queen, brood or eggs.

The place’s the proof?

Had we simply regarded for the presence of DWV we might have discovered it, however we particularly regarded for replicating virus by analysing injected/fed bees for the presence of an intermediate product within the replication cycle known as a ‘detrimental strand’ (an inverted copy of the virus genome used as a template to make extra copies, slightly just like the inked plate in an previous printing press).

Printing press

DWV does replicate in bumble bees however I’ve but to be satisfied that DWV is a menace to bumble bee well being. Our evaluation was comparatively crude, however we didn’t detect any overt pathology … although I acknowledge they might have felt garbage and had a yearning for chocolate. Extra work is required right here.

In reality, the identical actually applies to honey bees. Within the absence of a syringe (Varroa) DWV seems to do little or no harm to honey bees.

Osmia bicornis

Bumble bees get numerous consideration as they’re massive, comparatively straightforward to check, widespread and used commercially (for pollination in glasshouses and poly tunnels). However there are a whole lot of different bee species.

Does DWV infect these? Does it replicate and does it trigger illness?

Osmia bicornis is the scientific identify of the pink mason bee. This can be a solitary, gap nesting bee, widespread in England and mainland Europe. Its vary is increasing and it’s now current within the central belt of Scotland , Fife, Angus and with just a few information from additional north.

Osmia bicornis, the pink mason bee

Alexandria Schauer and colleagues have not too long ago investigated replication of DWV on this solitary bee (Schauer et al., 2023). Earlier research had proven that DWV was detectable in Osmia (of two completely different species) however, because the authors notice:

‘the mere detection of a virus is nonsynonymous with precise replication inside its host; it could reasonably mirror that a person has ingested or carries viral particles that aren’t actively replicating.’

They subsequently regarded for the presence of the detrimental strand of the virus, one thing that solely exists when the virus is replicating and that isn’t current inside the virus particle.

They examined an infection after micro-injection. While not essentially being a related technique of transmission ‘within the area’ it’s direct and bypasses a slew of innate intestine safety mechanisms which may stop an infection … keep in mind, the necessary query was does the virus replicate (and so doubtlessly trigger illness) in Osmia?

DWV replication within the pink mason bee

The lengthy and the in need of it’s that DWV does not replicate within the pink mason bee.

Injected bees survived in addition to the controls and the authors have been unable to detect the detrimental strand ‘smoking gun’ that confirms replication.

Nevertheless, in an fascinating twist to the story, Schauer and colleagues additionally extracted viruses from the pink mason bees 16 days after they’d been injected with DWV.

They then injected this virus preparation into honey bee pupae and demonstrated that the DWV extracted from the Osmia was nonetheless infectious for honey bees.

Wait a second … aren’t the honey bees already contaminated with DWV?

Properly accomplished, you’re paying consideration 🙂 .

The DWV initially injected into the Osmia was genetically distinct from the DWV already current within the honey pupae they subsequently injected. This allowed the authors to find out that the Osmia-extracted DWV remained infectious.

That is fascinating. 

It raises the likelihood that bees reminiscent of Osmia, though not themselves replicating DWV, might act as an intermediate and transmit the virus again to honey bees, or – doubtlessly – to different bees within the atmosphere.

Risk is the important thing level right here … not certainty. It’s tough to envisage a mechanism by which Osmia might transmit the virus to a different host. 

Predation is perhaps one route I suppose?

Because the virus just isn’t replicating in Osmia the quantity of virus will by no means be larger than that inoculated which – within the case of environmental publicity – means vanishingly little.

It’s value noting earlier than I transfer on that there’s one report of DWV replicating in one other solitary bee, Andrena haemorrhoa, which is a species of mining bee (Radzevičiūtė et al., 2017).

OK, sufficient a couple of virus you already learn about … right here’s one which’s new.

The brand new child on the block

A really current research has recognized a brand new honey bee virus, AmSV1, a wholly comprehensible abbreviation for Apis mellifera solinvivirus sort 1. The work is printed within the journal Viruses and is freely obtainable (Ryabov et al., 2023 ).

The virus was remoted from employee bees in a business apiary in Oregon that had skilled an ’traditionally excessive stage of colony losses’.

Current advances in nucleic acid sequencing and computation biology imply {that a} metagenomic strategy can be utilized to determine novel viruses. Metagenomic is a flowery phrase which means that the scientists characterise all the things from the bee pattern and remove all the things that’s already recognized from subsequent evaluation.

What’s left is the stuff that’s novel.

Bioinformatics phrase cloud

After all, it’s a bit extra sophisticated than that … the computational sieving (bioinformatics) permits plenty of little items of the unknowns to fall by which might then be pieced collectively – once more utilizing computer systems – to allow them to be recognized.

Intelligent 😉 .


Though AmSV1 is new, solinviviruses will not be. Related viruses have been recognized in a spread of invertebrates – beetles, aphids, the Asian honey bee, mosquitoes – and they’re recognized to trigger illness in hearth ants and cultivated shrimp.

Fireplace ants

Virus particles have been purified and the virus was injected into honey bee pupae. Utilizing an analogous strategy to that described above, the detrimental strand replication product was detectable, unequivocally demonstrating that AmSV1 is ready to replicate in honey bee pupae.

The destiny of those pupae was not talked about … did they emerge?

The distribution of the virus in grownup bees was investigated by slicing and dicing naturally contaminated bees into three elements – head, thorax and stomach – and testing every individually. Virus was present in all three elements, although not in each bee, suggesting it causes systemic an infection.

Having recognized the virus it was then attainable to develop molecular strategies to detect how widespread the virus is within the USA and, utilizing historic samples, whether or not it’s growing in prevalence and/or spreading geographically.

AmSV1 distribution

The historic samples have been restricted in quantity (and 2010 samples didn’t embody Oregon), however it definitely seems that AmSV1 is now widespread within the USA and that it’s spreading (notice for instance, AmSV1 was not detected in Texas, Alabama or Georgia in 2010, however that it was current in 2021).

Over the calendar 12 months, AmSV1 was rather more continuously detected in summer time months – June and July – although the variety of winter samples was very restricted and so could also be deceptive.

Lastly, the authors not directly surveyed AmSV1 distribution ‘globally’ by computationally screening databases of honey bee sequences from Brazil, China, Turkey and Europe (UK and Germany).

AmSV1 was not detectable outdoors the USA.

AmSV1 and queens

About 50% of the readers of this web site are within the USA.

AmSV1 might be already in your state or, if it’s not there already, it quickly might be.

The apiary-level sampling (i.e. pooled samples from 7-8 colonies from a single apiary) that contributed to the map above additionally concerned recording the degrees of some recognized pathogens – Nosema, Varroa, DWV, CBPV and so forth. – along with different issues that generally afflict honey bee colonies. These embody small hive beetle, EFB, drone laying queens, the presence of queen cells, queenlessness or wax moths.

It was then attainable, utilizing odds ratio evaluation, to find out if the presence of AmSV1 correlated with the presence of any of those recognized pathogens or area apiary observations.

There was no affiliation with Varroa, suggesting the virus might not be mite-transmissible .

Curiously, the one area statement that was statistically related when linked to the presence of AmSV1 was queenlessness.

Apiaries with detectable ranges of AmSV1 have been almost twice as more likely to comprise queenless colonies.

Does AmSV1 trigger queen losses? Or does the absence of a queen, or queen issues, make the colony extra prone to AmSV1 an infection?

It’s maybe notable that solinvivirus an infection of fireside ants reduces the fecundity (egg laying charge) of queens, leading to decrease ranges of brood and staff.

The paper concludes by stating that solinviviruses are poorly understood and that extra analysis is required. As an ex-virologist I couldn’t agree extra … however as an ex-academic I’m additionally conscious of a few of omissions from the paper which shocked me.


All scientific papers have omissions.

Stuff is omitted as a result of it’s going to be included in a follow-up paper that’s already in preparation. Therefore, the ’minimal publishable unit’.

It’s omitted as a result of the outcomes are – frankly – unconvincing and received’t stand shut scrutiny by the peer reviewers. In the event that they don’t like that bit maybe they’ll reject the manuscript?

They’re omitted as a result of they merely don’t match the story. The outcomes are good however their inclusion will trigger confusion – the researcher doesn’t perceive how they match, so how on earth will the reader cope?

Or, after all, they’re omitted as a result of they don’t really exist … the reader (me, on this case) thinks they need to exist as a result of I’d have wished the data earlier than I wrote the paper 😉 .

What occurred to these pupae injected with AmSV1?

If you happen to incubate larvae within the lab they pupate and ultimately emerge as grownup staff. If AmSV1 was extremely pathogenic to pupae you’d simply be capable of decide this. The virus was current in grownup bees (in apiary sampling) so I think it isn’t extremely pathogenic to pupae … or that it solely infects bees as adults.

What was the reason for the ’traditionally excessive stage of colony losses’ within the Oregon apiary?

This can be a business beekeeping operation. Certainly they might know if their colonies have been queenless? Had been the sampled colonies really queenless? Had been colonies misplaced in the summertime – when AmAV1 ranges are excessive – or winter? 

My suspicion is that AmSV1 was not the reason for these colony losses. There’s an ‘in preparation’ paper from the identical authors cited (reference 10) which hints at a distinct clarification …

Apiary-level virus complexes reasonably than particular viruses are related to elevated colony mortality in underperforming beekeeping operations.  

Which I’ll cowl when it lastly seems (if it’s fascinating sufficient).

So, must you be frightened?

No. There are many viruses on the market which are but to be detected. Actually hundreds of them. Massive scale sequencing initiatives have given us an inkling of simply how little we all know in regards to the vary and variety of viruses that infect animals (Harvey and Holmes, 2022).

The viruses scientists first recognized have been the simple ones to isolate, normally related to illness in people or the animals we rely on for meals (foot and mouth illness virus of cattle was the primary animal virus to be found, in 1898).

However we’re now realising that there are virtually limitless numbers of different viruses along with the key pathogens already detected.

I’m not conscious of a single dwelling species that doesn’t have a number of viruses that infects it.

There are even viruses of viruses.

Dastardly duo

A few of these yet-to-be-discovered viruses will undoubtedly be main pathogens however many, and doubtless most, received’t be.

Within the absence of an apparent and unequivocal affiliation between AmSV1 and honey bee illness (inside which I’m together with queen losses) I’d as a substitute focus upon the viruses we already know trigger issues if you wish to fear about something.

That affiliation at present doesn’t exist … so don’t fear about it.

The vast majority of colony losses happen within the winter, and the vast majority of these can normally be attributed to the ’dastardly duo’ of DWV and Varroa. As soon as these are below management all the things will get rather a lot simpler.


Harvey, E., and Holmes, E.C. (2022) Variety and evolution of the animal virome. Nat Rev Microbiol 20: 321–334 https://www.nature.com/articles/s41579-021-00665-x.

Gusachenko, O.N., Woodford, L., Balbirnie-Cumming, Okay., Ryabov, E.V., and Evans, D.J. (2020) Proof for and towards deformed wing virus spillover from honey bees to bumble bees: a reverse genetic evaluation. Sci Rep 10: 16847 https://www.nature.com/articles/s41598-020-73809-3.

Mazzei, M., Carrozza, M.L., Luisi, E., Forzan, M., Giusti, M., Sagona, S., et al. (2014) Infectivity of DWV Related to Flower Pollen: Experimental Proof of a Horizontal Transmission Route. PLOS ONE 9: e113448 https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0113448.

Radzevičiūtė, R., Theodorou, P., Husemann, M., Japoshvili, G., Kirkitadze, G., Zhusupbaeva, A., and Paxton, R.J. (2017) Replication of honey bee-associated RNA viruses throughout a number of bee species in apple orchards of Georgia, Germany and Kyrgyzstan. Journal of Invertebrate Pathology 146: 14–23 https://www.sciencedirect.com/science/article/pii/S0022201116302622.

Ryabov, E.V., Nearman, A.J., Nessa, A., Grubbs, Okay., Sallmann, B., Fahey, R., et al. (2023) Apis mellifera Solinvivirus-1, a Novel Honey Bee Virus That Remained Undetected for over a Decade, Is Widespread within the USA. Viruses 15: 1597 https://www.mdpi.com/1999-4915/15/7/1597.

Schauer, A., Bianco, N., Yañez, O., Brown, A., Albrecht, M., and Neumann, P. (2023) Deformed wing virus prevalence in solitary bees put to the check: an experimental transmission research. Frontiers in Ecology and Evolution 11 https://www.frontiersin.org/articles/10.3389/fevo.2023.1122304.



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