Saturday, January 28, 2006

Quick vaccine cycle?

It sounds like big news, and perhaps it is. Perhaps. A group at the University of Pittsburgh Medical Center has announced that it has produced a bird flu vaccine in just 36 days from start to finish. This compares with the six months or more needed for conventional egg-based vaccines. Moreover it protected mice and chickens 100% in challenges tests with H5N1 (Reuters).

The feat was accomplished by taking genetic sequence information for the hemagglutinin (HA) gene of an H5N1, making a DNA sequence to match it and splicing the DNA into an adenovirus, a causes upper respiratory tract infections ("colds") in humans. Adenovirus is a DNA virus (as opposed to influenza which is an RNA virus), but its genetic information still encodes for proteins, and in this case it was able to make the designated portion of the influenza HA protein when injected in animals, i.e., the animals were infected by a non-disease causing modified adenovirus which then produced in them the HA protein fragment (at least that's how the newswire accounts read [See addendum below]). Thus this is a live virus vaccine, but it contains no live influenza virus. The influenza protein induced both antibodies and an immune cell response (cell mediated immunity). This apparently protected the animals from a viral challenge that was sufficient to kill unvaccinated animals.

This team's efforts are not unique. A reliable source told me that several other groups are working on variations of this theme and that it isn't so hard to protect mice (and he implied others had done it without announcing it). But protecting mice is one thing, protecting humans another. So the proof of the pudding will be successful human trials. The LA Times reported that the Pittsburgh team is working with the FDA to begin human trials soon, perhaps within a month.

So the news is hopeful but perhaps not as exciting as appeared at first blush. Perhaps.

[NB: The paper is supposed to be published online in the February 15 issue of Journal of Virology but as of this writing (late night 1/27/06) had not yet appeared on their site, so I am working off of wire service reports.]

Addendum: I found the abstract here but I can't get the Full Text yet as my proxy server seems to delete cookies automatically. The Abstract says the adenovirus is replication incompetent, which must mean like they are using it in cell culture to produce the HA protein. I will add to or correct this if and when I find out more. Anyone who has managed to get the article before I do is welcome to weigh in.

To kind readers who have offered us the .pdf: Thanks to one of your number (hat tip, Selise) I now have a copy of the vaccine paper and hope to read it tonight (I have been on the road almost constantly and am a bit tired, so I'm not sure I'll manage). Will report back once I have had a chance to digest it. It sounds like my first reading of the wireservices was more or less correct, however. They made the adenovirus into a vector to get the sequence into human cells where it the cells manufacture the HA or portions thereof.