I know quite a lot about this area and have advised others in the past.
An HIV positive person can obtain a PR visa, but it can be challenging and it will increase the amount of time to process your application.
Your Panel Physician (formerly "Designated Medical Practitioner") should have drawn blood for an HIV-1 RNA test ("viral load") and a CD-4 test (a specific type of white blood cell used for cell mediated pathogenic response). Those results will then be forwarded to Immigration Medical Service. Their decision may be predicated, at least in part, on the province in which you will be landing. For example, if you plan on landing in BC, while they will go through all the process in the end because BC provides 100% coverage for the drugs unless your wife is not expected to require them for most of the next 10 years she will likely be declared inadmissible, though I can provide you with some information that you can use to argue against this decision.
Drug coverage varies by province, though, so a complete analysis cannot be done without that information.
Normally, what IMS will do next is send a sealed letter to you to take to the Panel Physicial (DMP). Normally this will ask for additional information and whether or not you will require treatment in the next 5-10 years. What this means is that you need to be looking for a sympathetic doctor now. Ideally, you want one that can either say definitively or probably that she will not require treatment within that time period. Not every doctor will say that, so you may wish to consult with more than one.
If after reviewing the additional medical information they determine she will require medication in the 10 year time period, they will advise you that she is "probably" medically inadmissible. This is done by way of a fairness letter. You will have 60 days to respond to the fairness letter.
You may challenge the finding of the medical condition, e.g., she had a "false positive". This is actually quite likely. The doctor may tell you the test is 99.6% accurate, but will not advise you that the positive predictive value (PPV) is much lower than that, because the prevalence of the condition is very low in the general population.
You may challenge the medical officer's estimate of costs. This is an area in which I can provide you with guidance, particularly if you can present a particular treatment regimen to her doctor and have the doctor agree that it is a viable treatment model - this is because one approved treatment is now made up of generic medications that have much lower cost and thus do not exceed the excessive demand cost threshold.
You may provide a plan to mitigate costs. This can include insurance plans, NGOs that will pay for treatment, and health savings plans.
If you do receive or expect to receive a fairness letter, I would strongly suggest you engage an attorney to assist you. I can recommend someone who specializes in HIV medical inadmissibility cases and can point out a handful of other attorneys specializing in medical inadmissibility. A well formulated response to the fairness letter potentially will overcome the initial inadmissibility conclusion and ultimately lead to a successful conclusion. In addition, it will set the stage for a successful challenge to a negative decision.
If you are refused, you may challenge the refusal in Federal Court. That will require you have an attorney. CIC's track record in medical admissibility cases for FSW applications is not good - they lose about 75% of such cases according to my own review of case law. If you are interested, look up the following four decisions: Sapru, Rashid, Companioni and Ortiz at canlii.org. These are all on-point cases with respect to medical inadmissibility and the last two are specific to HIV (CIC lost both of those cases).
If you need more information, feel free to ask (I won't hand out attorney names in public, but will send them privately.) You don't have 10 posts yet, so you won't be able to send PMs.
A good news!