Crocodile's Immune System Kills HIV

ASEville writes "In an ongoing effort to stop the spread of HIV, scientists in Australia have discovered that crocodiles can fight off HIV and kill the virus. This is a major boon to medicine because the crocodile serum can also fight things that are penicillin resistant such as staphylococcus aureus."

Comments

What a hack

[Stickerboy]

"The scientists hope to collect enough crocodile blood to isolate the powerful antibodies and eventually develop an antibiotic for use by humans."

Antibiotics kill living bacteria. There isn't a single antibiotic that can disable a virus (like HIV), which isn't even alive.

The scientists probably hope to use modified crocodile immunoglobulin the same way we use animal-developed immunoglobulin as a tetanus antitoxin for patients who haven't been immunized... kind of a booster shot for patients fighting an HIV infection. The problem with animal-developed antibodies is that the human body recognizes them as foreign, and soon starts to mount an immune response against them as well.

not what it's cracked up to be

[larry bagina]

I'll reserve a real judgement for when more information is published in Nature or Science, but it doesn't appear to be anything useful.

The human immune system is fully capable of killing HIV. However (dumbed down enough for Reuters readers) HIV infects T4 Lymphocytes, so killing the virus means killing your own immune system, and you die of obscure diseases.

The antibacterial angle sounds promising, though.

Re:not what it's cracked up to be

[Anonymous Coward]

The body CAN indeed kill HIV however it can't completely eredicate it. But it comes closer than you seem to think.

When a person becomes infected with HIV, the amount of virus in the blood explodes - it goes from 0 zero copies per mL to several million copies per mL. This triggers an immune reaction (which is why a large percentage of patients get flu-like symptoms during the earliest stages of infection). But guess what, after a few additional more weeks the body has sort of taken control and the viral load drops so low that it is undetectable (and we can measure down to a few hundred copies per mL). The initial symptoms go away and for some period of time it may be impossible to give any direct evidence of the infection. Note that this is what occurs with treatment of any kind!
HIV-tests detect the body's own antibodies against HIV but it may not be possible to detect the virus itself.

Replication must however continue to occur on a low level because over the years most HIV patients experience a steady decline of CD4+ cells, the cells that HIV most frequently infects. After some time this decline starts to accelerate until the CD4+ count is so low the patient gets sick from all kinds of diseases.

It is not known exactly what is the cause of this decline. It seems weird that the body can fight off the virus at millions of copies per mL without suffering much damage while the last bit of replication (probably caused by latently infected cells) is so damaging. One thing that is known is that the CD4+ cells do not die as a direct result of being infected with HIV. In fact it is a very small percentage of CD4+ cells that are infected at any given time. CD4+ cells may be dying because of apoptosis (cellular suicide) triggered in some way by chemicals in the blood stream or actions of other cells infected with HIV. The hole flow from HIV infection to AIDS also involves certian mutations taking place in the virus' gene. It may be these mutation that causes the accelerated decline but the causation may also be the other way around.

Mod down yet Another Misleading Slashdot commentor

[Anonymous Coward]

"There is nothing in the article to suggest that they have isolated the specific component that kills HIV, let alone determined that it is safe for human injection."

I know the /. commentor's don't read the articles submitted all the way to the end, so here's a bit towards the end that really matters:

"The scientists hope to collect enough crocodile blood to isolate the powerful antibodies and eventually develop an antibiotic for use by humans ... There is a lot of work to be done. It may take years before we can get to the stage where we have something to market," said Britton.

Re:HIV-AIDS

[nietsch]

The hypothesis that aids is not caused by hiv has been very thoroughly disproven AFAIK. The (probable) reason one 'scientist' kept claiming that was because it made him 'famous'. Other parties that wanted to deny AIDS for political resons kept supporting this guy or held on to his theories. I can't remember his name.

As for funding: Would you give funding to 'scientists' that claimed the earth was flat or created in 7 days with no evolution? Lunatics don't get money because they are lunatics, not because their ideas need to be suppresed by gouvernment.

There are more countries in the world doing AIDS research than the US, so any errors caused by your strange funding policy would be quickly corrected in the rest of the world. The first breaktrough successes were made in Europe(france) IIRC.

As for the causes of death with AIDS: that is what you get when AIDS takes out your immune system: you die of the first petty illness that comes along.

So this 'AIDS is not caused by HIV' meme is nothing but FUD, please don't spread it any further.

Quick, damage control!

[krayzkrok]

Ho, never thought I'd be the subject of a Slashdot news report.
Time to clarify things.
TFA contains a number of errors. First the statement I made about HIV is true, but as others have pointed out it does not mean we've found the cure for AIDS. It simply means that we've compared alligator serum and human serum and found the former significantly more effective at killing the HIV virus than human serum. It was intended to illustrate the overall efficacy of the crocodile / alligator immune system, that was all.
Second, these are not antibodies. Croc immune system works primarily through the innate or complement system, which does not involve antibodies. It's a simpler and more primitive immune response than the adaptive immune system that is key for mammals, but the advantage is that it's very direct and hence difficult for bacteria etc to evolve resistance to. It's "primitive" nature may be behind its effectiveness.
The main finding here is that the alligator / crocodile immune system is far more effective at killing a wider range of bacteria (gram +ve and gram -ve), viruses and fungi than our own immune system. When you've evolved over 235 million years, and your daily social behaviour involves biting limbs off other crocs, you need a good immune system! It clearly has potential medical implications down the line, but that's a long way off yet. First we have to fully understand what makes croc immunity tick. We are still trying to purify a protein which we believe is an antimicrobial peptide, but hopefully that will happen very soon after this recent work.
Eventually if anything does come of this, and we can isolate a "factor" that has human medical implications (and is safe for humans, unlike the far more effective chlorine bleach) it would indeed be synthesised. Adam Britton

Re:Quick, damage control!

[krayzkrok]

This isn't my theory, and I can't seem to pull the appropriate citation up for you, but the gist of the paper was that the innate immune system is very much a secondary response in humans and hence has always been viewed as "primitive" (hence the quotes). Reptiles (and some other groups including fish) never developed a particularly effective adaptive immune response like mammals, but instead their innate immune system naturally evolved over time to become more effective than the innate system in mammals. The main advantage of the innate response seems to be its non-specificity. The results we're seeing in alligators, crocs, sharks etc seem to bear this out to a degree. Inferior? There's no such thing, in my opinion - each system is well-adapted for each user even though it's never perfect. If it was we'd never fall ill. So perhaps we can cheat a little and steal the good bits from our (very) distant relatives...?

Adam Britton

Re:Crocodile Spam

[krayzkrok]

This scam fed off our initial pilot study findings, back in 1998. There was worldwide media exposure at the time because of the demonstrated ability of the croc serum against antibiotic-resistant bacteria (S. aureus). They used this media coverage in a weak attempt to add credibility to their product.

Yes, we have tried suing them (mainly for defamation, because they claim we endorse this crap) but it's very difficult to sue companies that apparently don't exist.

Adam Britton

Re:Research Quality

[krayzkrok]

Er, why is research only valid if it comes from an academic institution? Crocodylus Park (the name for the facility run by Wildlife Management International, of which I am an employee) is run by professional biologists who just happen to also run a tourism faclitity to get science across to the public. The fact that we're private doesn't have anything to do with the quality of our research - we still publish in peer-reviewed journals so it's open to international scrutiny like any other research.

We're also collaborating with McNeese State University in Louisiana for this project.

Adam Britton

Re:Antibodies.... or not?

[krayzkrok]

Correct, this is what we're talking about primarily. The news article was wildly inaccurate and embarrassing to read quite frankly!

We don't talk about defensins because we're not sure yet that defensins are involved. We suspect they are, but until we purify and sequence the proteins we're looking at we can't be sure. Hopefully this is only weeks away.

Re:Yet Another Misleading Slashdot Summary

[krayzkrok]

Well Mr Angostura, you're as bitter as your namesake aren't you?
First of all, if it isn't clear that this news report is crammed full of factual errors, then perhaps it isn't obvious that what I said may have been completely misquoted? After all, the guy almost had me describing a new type of "crocodile antibodies"! This was "quoted" from a phone interview where I could hear the journalist typing in the background, so it's hardly a direct quote. The only part I definitely said word for word was the "gun to the head" line.
And I'm not Australian, by the way (not yet at least) so I have no idea how to operate a sheep dip.
Yes, we did discover an antimicrobial peptide (probably a defensin) several years ago. This is a continuation of that research.

Adam Britton

Re:Yet Another Misleading Slashdot Summary

[krayzkrok]

One final comment on this - I need to vent! Bear in mind that these news reports are *way* off the mark in their reporting. The vast majority simply copied the Reuters article and diluted the facts yet further.

It was Reuters who picked up on the HIV aspect and blew it out of proportion. It was never the goal of the study to combat HIV - it was just an interesting test. They even managed to misquote me almost completely. The main focus has been the antibacterial properties of the blood.

Also, the part about the immune system being "too powerful" is something they pulled out of their cloaca. We're quite aware, as scientists, that it's far too early to start talking about marketable antibacterial drugs. The various factors that provide crocs with their powerful immune systems may not have any safe human medical use whatsoever. The fact that they *could*, however, is obviously interesting, but too many people here are taking this dodgy news report too literally. Don't get me wrong - this is exciting stuff and it could have health benefits down the line, but I don't like seeing this work getting misrepresented like this.

There are peer-reviewed papers out there (check Merchant, principal author) and this work is being written up at the moment (check Merchant and Britton). They'll be far more informative than anything you'll read in the paper.

Incidentally, we can't submit this to Nature because back in 1998 we did a pilot study, the lid of which was blown off from an unexpected source in a fit of excitement! So it's far too late for that - croc's out of the bag, etc...

Adam Britton

Re:Yet Another Misleading Slashdot Summary

[bcwengerter]

I apologize if I'm being redundant, but as of the time I'm writing this, there are 442 comments when browsing at -1, so I can't guarantee that I haven't missed something.

In any event, I thought it might be helpful to post a link on PubMed to the abstract of the journal article to which the author of the Reuters article seems to be referring. At least, it's coming from the same lab and institution with which Dr. Britton (on his site) mentions having a collaboration. Any other references would be greatly appreciated.

Here's the full text for those who are interested:

1: Antiviral Res. 2005 Apr;66(1):35-8.

Antiviral activity of serum from the American alligator (Alligator mississippiensis).

Merchant ME, Pallansch M, Paulman RL, Wells JB, Nalca A, Ptak R.

Department of Chemistry, McNeese State University, Box 90455, Lake Charles, LA 70609, USA. mmerchan@mcneese.edu

Serum from wild alligators was collected and tested for antibiotic activity against three enveloped viruses using cell-based assays. Alligator serum demonstrated antiviral activities against human immunodeficiency virus type 1 (HIV-1; IC50=0.9%), West Nile virus (WNV; IC50=4.3%), and Herpes simplex virus type 1 (HSV-1; IC50=3.4%). The inhibitory concentration (IC50) is defined as the concentration of serum that inhibits 50% of viral activity. The antiviral effects of the alligator serum were difficult to evaluate at high concentrations due to the inherent toxicity to the mammalian cells used to assay viral activities. The TC50 (serum concentration that reduces cell viability to 50%) values for the serum in the HIV-1, WNV, and HSV-1 assays were 32.8, 36.3 and 39.1%, respectively. Heat-treated serum (56 degrees C, 30 min) displayed IC50 values of >50, 9.8 and 14.9% for HIV-1, WNV and HSV-1 viruses, respectively. In addition, the TC50 values using heat-treated serum were substantially elevated for all three assays, relative to untreated serum (47.3 to >50%). Alligator serum complement activity has been shown to be heat labile under these conditions. HIV-1 antiviral action was heat-sensitive, and thus possibly due to the action of serum complement, while the anti-WNV and anti-HSV-1 activities were not heat labile and thus probably not complement mediated.

PMID: 15781130 [PubMed - indexed for MEDLINE]