HIV Superinfection boosts immune response

[buginme2]

Interesting, not only does superinfection happen but apparently it can help you fight HIV.

http://www.sciencedaily.com/releases/2012/03/120329225052.htm

[JazJon]

Interesting, not only does superinfection happen but apparently it can help you fight HIV.

http://www.sciencedaily.com/releases/2012/03/120329225052.htm

Wow, never even thought of it this way before.  It makes sense, hopefully they learn something from it.

[mecch]

It seems these women were also not on HAART.

[spacebarsux]

Interesting, not only does superinfection happen but apparently it can help you fight HIV.

http://www.sciencedaily.com/releases/2012/03/120329225052.htm

Heh. 

[Ann]

Articles that tell half a story like this do my head in.

For example, it is not explained whether they were talking about two infections from two different clades (which is what I suspect) or if they were talking about reinfection with a drug resistant strain. I don't think they were talking about resistant strains, but it remains unclear in the article.

It is also not clear whether or not these women were treatment naive - although I suspect they were (like Mecch).

I really do think they're discussing reinfection with two different clades, rather than reinfection with a drug-resistant strain. Otherwise, I can't see them being so excited that this may be an inroad to a workable vaccine.

The most common clade is "M" - and M has eight different subtypes (labeled A through H). These subtypes are generally associated with different geographic regions.

There are two predominate subtypes in East Africa (which is where Kenya - the site of this study - is located) and I'm thinking that it is very probable that the women they were looking at were infected with both clade A and D - the two prevalent clades in East Africa.

Clade B is most prevalent in Europe, N. America and Australia; C is more prevalent in West Africa, South Africa, India and China. Clade E is prevalent in Thailand. I'm not too sure where clades F and H are found. I believe I have a clade A (if anyone cares lol).

A very simple explanation of clades can be found here and a discussion of how clades relate to the search for a vaccine can be found here. Also, google "hiv clades" and you'll find a whole lot more on the subject.

Anyway, this is why I suspect these women in the study were superinfected with two different subtypes/subclades of clade M and the excitement is all about what this may mean for vaccine research. I'm not so sure that reinfection with a drug-resistant strain would garner as much excitement in the realms of vaccine research.

By the way, if they're going to insist on dumbing-down articles to this extent, I wish they'd stop using the term "superinfection" rather than its synonym "reinfection".

When most people see the term superinfection, they think super as in super-duper (ie extra strong, like Superman) rather than super as in superimposed - one infection superimposed on top of the other. It's the superimposed definition that is intended when the prefix "super" is used this way.

I would imagine that superinfection is the scientifically preferred term because reinfection could mean being reinfected with the exact same virus, and "coinfected with a drug-resistant strain" or "coinfected with a different clade" are just too unwieldy.

A lot of people miss this distinction, unless they're etymological geeks like me. (An etymological geek is someone who is fascinated by word origins and the study of words in general. If you were thinking I like bugs - those people are entomological geeks. Notice the N.)

PS - when superinfection is discussed amongst people in "the West", they are usually talking about being infected with a "wild-type" virus and then being reinfected with a drug-resistant strain. Being superinfected with two different clades is different as both clades may be sensitive to all drugs.

[tednlou2]

An update about the confusion this has caused:



       
Study of HIV Superinfection and Neutralizing Antibody Responses Causes Confusion

By Richard Jefferys

From Treatment Action Group

April 16, 2012

On March 29th, PLoS Pathogens published a paper reporting that women superinfected with two HIV variants are more likely to generate antibody responses capable of neutralizing a broad array of viral strains (known as broadly neutralizing antibodies or bNAbs). The work was conducted by the laboratory of Julie Overbaugh at the Fred Hutchinson Cancer Research Center (FHCRC) in collaboration with the University of Nairobi. FHCRC issued a press release to publicize the work entitled "Study finds HIV 'superinfection' boosts immune response." In retrospect, this may have been a poor choice of words, as it can easily be misinterpreted to suggest that the immune response of the superinfected women was boosted in a way that was beneficial to them; today at least one press story has done just that, stating: "A new study suggests that women who have been infected by two variations of HIV may have a better chance of suppressing the virus then those only infected with one." This is completely untrue.

As with prior studies identifying bNAbs in people with HIV, the responses identified by Overbaugh's lab were of no benefit to the individuals they were sampled from. The bNAbs are not present at high enough titers to lead to control of HIV viral load or slowed disease progression in chronic infection. The study is nevertheless potentially important for preventive vaccine development, because if similar bNAbs could be induced by a vaccine they might well be able to prevent the acquisition of HIV infection (which involves exposure to a relatively small amount of virus). Similar confusion occurred with the prior studies reporting bNAb isolation, and it is clearly exacerbated by the adoption among vaccine researchers of the term "elite neutralizer" to describe the individuals bNAbs can be sampled from, which is easily mixed up with "elite controller," the designation given to a different subset of individuals with HIV who maintain undetectable viral loads in the absence of treatment.

In terms of what the study does actually show, it offers intriguing and potentially important evidence that HIV variability can be linked to the generation of antibodies with broad neutralizing activity. This phenomenon has been suggested before by Guido van der Groen, based on studies of individuals infected with recombinant HIVs (viruses made of two different clades that have recombined). However, while van der Groen mentioned the association during a talk at a meeting in 2000, it does not appear that the data were subsequently published (I covered the van der Groen's talk for the Sept-Nov 2000 issue of the IAVI Report, see page 17).

The findings may offer encouragement to the researcher Julie Hurwitz, who has long been working to develop an antibody-based HIV vaccine that comprises a cocktail of multiple different Env proteins derived from a variety of strains. The one currently ongoing HIV vaccine efficacy trial, HTVN 505, involves candidates that encode Env proteins from HIV clades A, B and C, so the results (expected in 2015) may also contribute to understanding whether mixing diverse antigens can increase the chance of generating bNAbs.

http://www.thebodypro.com/content/66709/study-of-hiv-superinfection-and-neutralizing-antib.html