Vaccine Breakthrough: AIDS

[DrDan]

Fort Dodge Laboratories last week released it's new vaccine for FIV (Feline Immunodeficiency Virus). We have already started vaccinating cats for this killer disease.
FIV is caused by a Lentevirus (slow virus) similar to the virus that causes Human AIDS and West Niles Disease. Although it is very similar to the Human AIDS virus FIV cannot infect humans!

The virus is spread almost exclusively from cat to cat by bite wounds. During the first wek or two after infection, lymph nodes may enlarge as the virus infects both neutrophils and T-Lymphocytes. The virus may then go into a latent period that may last from several months to years. Eventually the virus can recrudesce and drop neutrophil and lymphocyte counts to low levels. These immune cells normally hold back infections by bacteria, viruses, protozoa and fungi. Once the immune system is compromised virtually anything can happen. Some signs include gingivitis (infected gums), stomatitis (infected mouth), poor hair coat, weight loss, respiratory infections, diarrhea, etc., etc. Both FIV and Feline Leukemia are always to be suspected in any cat with recurrent illness.

I have included a couple of links to fillow and better understand the disease:
http://www.fivtest.com/

Check them out...

Better yet if your cat has any possibility of being bitten or biting another cat (especially intact males) go to your vet and get the new FIV vaccine. It takes three doses initially 2 to 3 weeks apart and then an annual booster. 3% to 15% of the nations cats are carriers so it can easily infect your cat.

You may wonder why Fort Dodge caould develop a vaccine against FIV and the whole world cannot develop a vaccine against human AIDS. It is quite simple... In the animal world, challenge studies can be done - not so in the human population. I'm sure this medical breakthrough may pave the road to a cure for Human AIDS in the future.

It is absolutely incredible! I am so pleased to be able to provide this life-saving vaccine to my patients.

Dr Dan

 

[rancar]

Thanks DrDan for this very useful information. I'll keep it in mind if I think my cat may ever be impacted.

 

[Scott_in_WVA]

Thanks Dan.....

 

[dmccarty]

Dr Dan,

What is a "challange study?"

Thanks,
Dan McCarty

 

[DocHeb]

<font color=blue>What is a "challange study?"</font color=blue>

Short answer:
For vaccines, take the test subjects and vaccinate 50% (the treatment group) - don't vaccinate the other half (the "control" group). Expose both to the disease and see how protective the vaccine is. This is the best method to determine efficacy.

Long answer (to explain some of the difficulties with human research):
For human testing, you have to have a control group (e.g., for AIDS it would most likely be gay men without positive testing for HIV). This group does not receive the vaccine. Since they're at risk from their lifestyle, this control group can be expected to get the disease at a certain rate over a period of time. Take another group of gay men (matched for age, other health history, and sexual risk-taking behavior) and give them the vaccine. Compare the HIV conversion rate between the two groups, and see if there is some beneficial effect. It is ethical to not give the vaccine to the control group, since the vaccine hasn't been proven to be efficatious. If fact, some vaccines can cause more trouble, outweighing the benefical effect of the vaccine. While the study is ongoing, it may become apparent that the vaccine is quite safe and beneficial, and the control group is horrendously worse off without the vaccine. Or, the vaccinated (treatment group) is having increased health problems. If either of these happens, the study may be ended prematurely (this just happened with the ongoing Estrogen/Progesterone study for post-menopausal women - the study was ended early due to much higher risks for the treament group).

Once a vaccine has been shown to be safe and efficatious, ethics mandate that no further human studies can have an unvaccinated control group. This makes it more difficult to test Vaccine #2. The new control group would get Vaccine #1, and the treatment group would get Vaccine #2. It becomes increasingly complicated and statistically harder to show improvements, and the studies must have more and more patients over longer times to show higher efficacy. Historical controls can be used, but they become less valid over time.

One interesting historical sidenote to human testing. The <A target="_blank" HREF=http://www.npr.org/programs/morning/features/2002/jul/tuskegee/index.html>Tuskegee Syphillis Study</A> withheld penicilin treatment from patients with syphillis, to learn the natural progression of the disease. It made for great scientific study, but was a low point in the ethics of medicine.

 

[dmccarty]

DocHeb,

Thanks for the definition. /w3tcompact/icons/smile.gif

I noticed in your profile that you where waiting for a place
to store your tractor. If you got land what are you waiting
for? /w3tcompact/icons/smile.gif I keep my tractor chained to a tree for "storage."

/w3tcompact/icons/smile.gif

Course we usually don't get much snow down here.... /w3tcompact/icons/smile.gif

Thanks,
Dan

 

[Anonymous Poster]

Doc Heb,

Question #1

In the case of an on-going study, if the treatment group is benefiting greatly from the new vaccine and the control group is suffering from not having the vaccine, your note indicates that the study may be terminated prematurely. Once the study is ended, can the control group get its hands on the vaccine or must they wait for Phase II or III to be completed?? Maybe they could join the control group for the next phase.

Question #2

Can "crossovers" occur during a study (i.e., moving from one group to another due to a progression of disease??)??? Does this totally mess up the stats??

 

[TresCrows]

Is a lentavirus a form of retrovirus? ,was not aware West Niles Disease was a retrovirus? is it? I thought, maybe wrongly, that AIDS complex was the only human retrovirus known to cause disease? I know that some oddities have occured in studies Cytomeglavirus (CMV) and Mononucleosis in connection with AIDS early on and latter Chronic Fatigue Syndrome (CFS) and neither were conclusive. These viruses are similar to herpes virus and are not retroviruses but often lead to the actual cause of death in AIDS patients.
I, really doubt, that this new break through for our kitty kat friends will help all those folks in Africa who are dying--right now but we can all be hopefull, last I read a cure for AIDS was years or decades away and a effective vaccine at least a decade away! Has anyone read about nanotechnology and micro machines used to destroy viruses.
Could it be that viruses are the intelligent form and we simply exist to further their existence, that we are actually designed to be viral reproductive media. J

 

[DocHeb]

Answer #1:

Treatments still under trial would not be available until they go through the entire FDA approval process, with the only exception being entry into another trial. There is an understandable summary of the FDA process at <A target="_blank" HREF=http://www.genzyme.com/research/clinical_trials/trial_process.asp>Genzyme</A> web site.

Answer #2:

Having patients move around from one arm of the trial to another makes the statistics difficult and generally makes the data untrustworthy. Occasionally the FDA will allow "compassionate" use - If the patient has a known terminal disease, they'll allow use of a trial medicine outside of a study. If the person lives longer or gets better, that data is added to the body of medical knowledge, but really can't be used to prove anything.

Most trials have "blinding", which means the patient doesn't know if he's getting the control "placebo", or the test drug. The best trials have the treatment providers blinded also. This makes sure that there isn't a bias injected into the study. The patient should also be assigned randomly into the different treatment arms of the study. The data is accumulated and analyzed by persons not providing direct patient care.

Researchers strive to blind the studies as best possible. In a recently released study of Knee Arthroscopy ("knee scope") for Degenerative Joint Disease, all the patients went to surgery for the scope, but the control group had skin incisions made with no internal arthroscopic manipulation. This is called a sham surgery. The treatment group had the full procedure that had been the routine for DJD arthroscopy. The patients and the follow-up physicians didn't know who had the full or the fake surgery. Interesting - they had the same success rate for improvement (meaning, arthroscopy for pure DJD is probably not worthwhile).

If the trial is for chronic therapy of a disease already present, the ultimate study is a "crossover" study. During the first half of the test period, 50% get a placebo (or one test drug), and 50% get a second drug. At the half, the groups are switched. Nobody knows who's on what until the end, when the randomization code is broken. Improvements and relapses are analyzed, and the benefit/risks of the treatments are determined

 

[DocHeb]

We're close enough to the big, bad city that I don't feel comfortable about leaving anything out, no matter how big the chain. If they can cut the chain when I buy the chain, they can cut the chain to steal the tractor (and probably steal the chain also!) /w3tcompact/icons/smile.gif

The garage is lockable, but the budget crunch of finishing the house will mean a little more delay of tractor gratification.