Question

Do all viruses have spikes?

Answer 1

As far as I know, yes. All viruses have those spikes that are sometimes called "peplomers."

They need them, in order to stick onto cells, and get inside the cells,
so that they can infect the cells,
and replicate themselves.

Take a look at this picture:
http://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/PhageExterior.svg/491px-PhageExterior.svg.png

It's a picture of a BACTERIOPHAGE.
A virus that infects bacteria.

These viruses also have spikes,
but they're a little different.

The spikes aren't on the virus's orange capsid, you see.

They look like little feet, instead.

All of the human viruses, that I know, have spikes on their capsids.

Answer 2

So helical viruses have them as well?

Answer 3

That's a good question! Why didn't I think of that? Hold on here will you please?

Answer 4

I will. Thank you for your help.

Answer 5

The answer to this question might actually be "no," I'm very sorry.

See, I was thinking only of HUMAN viruses.

All of the human helical viruses, that I can think of, are ENVELOPED.
They're surrounded by a lipid envelope. A sort of bubble.
And THESE helical viruses DO have spikes.

But there are some that are NON-ENVELOPED,
like the Tobacco Mosaic virus.
And it doesn't seem to me like they have spikes.

Answer 6

I thought that was the case, but was not sure. So naked viruses do not have spikes? Do they just use the highly specific molecules/chemicals on their surfaces to attach to the specific receptors?

Answer 7

Good question. I don't know why I never thought of it until now,
but I'm asking myself the same question.

How would a virus, without spikes, infect a cell?

And your idea could actually be right. I'll do some research.

Answer 8

I mean SOME naked viruses, like the rhinovirus that causes the cold, DO have attachment proteins.

Answer 9

Of course, that's not a helical virus.

Answer 10

I remember reading in my Microbiology textbook that the highly specific molecules allow the virus to adsorp to the host surface. Would these be on the ends of the spikes? Because with a lipid bilayer, it would make sense that the virus would need spikes as the bilayer is not its natural capsid, and would not contain the chemicals. Would the naked viruses just have the chemicals on their surfaces that would attach (differently, of course) to the receptors on the host surface?

Answer 11

From my textbook, "Molecules on virus surface impart high specificity for attachment to host cell".

Answer 12

My real question is whether there are viruses that do not have spikes, and what their means of adsorption is.

Answer 13

Well if it's in your book, we'll take it at face value.

I just wonder what those molecules are.

If we were talking about anything but non-enveloped helical viruses,
I would think that the "molecules" were the spike proteins.

~~~~~~~~~~~~~~

Yes, it does seem that some viruses do not have spikes.

I admit, I haven't read a lot about non-enveloped helical viruses, like the tobacco mosaic virus.

Your book suggests that they may use another type of chemical component, to attach to cells.
And I'm wondering what those molecules and chemicals might actually be, if not attachment proteins.

Answer 14

Are attachment proteins the same thing as glycoprotein spikes?

Answer 15

Yes.

Answer 16

I'm trying to figure it out right now. Browsing a few articles about the tobacco mosaic virus.

Answer 17

I took notes on a medical school virology lecture, from back in 2009.
And at one point, we talked about non-enveloped icosahedral viruses, like the rhinovirus.

These viruses can get right through the cell membrane,
even without a lipid envelope.

Sure, they have attachment proteins,
and they therefore can attach to the cell membrane.

But exactly HOW they get THROUGH the cell membrane was unknown.
The professor told us that scientists hadn't yet figured that out.

That was years ago,
but as of now, I still can't seem to get any answers.

You wanted to know if ALL viruses have attachment proteins. Spikes.
And as far as I can tell, the answer's "no."

But then we wanna know HOW these viruses manage to get into cells,
WITHOUT a lipid membrane, OR attachment proteins.

You say that your microbiology book mentions "highly specific molecules" that allow the virus to attach to the cell, AND get inside it.
Do you think that would apply to these non-enveloped helical viruses, with no spikes?

I can't find anything to extrapolate that concept, I'm sorry.

Answer 18

I am not too concerned with how they get in, just how they attach in the first place. I was mostly wondering whether the spikes were required for specificity. Maybe the ones without spikes are not specific like those with the spikes. I am sure the viruses that manage to just get in have a certain polarity and maybe mimic the molecules that can diffuse into the cells. I have no idea. But this definitely helped, thanks again

Answer 19

Yeah I can tell you that spikes are required for specificity.

Like...certain spikes will only bind to certain types of cells.

And that's a very good point.
Viruses without spikes wouldn't have to bind to anything specific.

But yeah, I've hit a wall here. I wish I could tell you more.

Answer 20

You have helped immensely. Thanks for your time!

Answer 21

It's no problem.