Virology pop quiz

by Vincent Racaniello on 24 June 2009

BaculovirusThis week’s pop quiz involves analysis of an AFP news article entitled “US company makes first batch of swine flu vaccine“. The article reports that Protein Sciences has been awarded a contract from the US Department of Health and Human Services to produce a vaccine by synthesizing the viral HA protein in insect cells. Here are two paragraphs from the article:

They warned that the virus could mutate during the southern hemisphere’s flu season before returning north in a more lethal form in autumn, in a pattern similar to that seen in the deadly 1918 flu pandemic, which claimed an estimated 20 to 50 million lives around the globe.

The CDC (Centers for Disease Control and Prevention) sent us a dead virus, which is perfectly safe, and then we extracted genetic information from that virus.

What is wrong with these statements? Post your answers in the comments section.

For extra credit, critique this statement from the same article:

Protein Sciences’ technology is also safer “because these caterpillars don’t have any association with man or other animals, so there’s no chance for their cells to learn how to propagate human viruses,” Adams told AFP.

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  • ian shaw
    The 1918 flu pandemic started in the USA although it was often called "Spanish Flu" from the outreak in Madrid and no evidence that the southern hemisphere had anything to do with its source or disasterous spread

    Also "dead virus" is poor terminology - viruses have an active replication stage with phases when they are outside their host cell and in an inert form, but viruses cannot be said to be living or dead as such. They can be inactivated or "killed" for vaccine usage by inactivating certain functions
  • rev
    the problem with using live attenuated vaccine would create risk of failure to seroconvert during 1st and 2nd administration. using only rna vaccine would have limited immune response as long the rna remains the same which is very imposible as antigenic shift or mutation rate is high.
    viruses are particles, lowest in the organisms levels. cells can be propagated to produce viral protein through genetic engineering = recombination. the production of the viral protein can be harvested from the cells and used as vaccine like DNA vaccine i think. freeze dry the protein and administered or fine a route to administer the protein via carrier.
  • May i guess?
    1. "sent us a dead virus", virus is not alive, virus is only just matter, complicated matter.
    2. If caterpillars cells don't have any association with man how influenza viruses grow in there?
  • ET
    1. As for the 1918 pandemic, it was in the same hemisphere all three times; US in summer, US in autumn/Winter, and US next spring/Summer. Yes, it moved around by ship, but Camp Funston in Summer, and New York Harbour in October (although Im trying to channel 'The Great Influenza', and its been a few years, so don't quote me on that last part.) Maybe it was Baltimore?

    2. I would suspect that the CDC sent an inactivated virus (not actually dead) which they then had to grow in culture. Inactivated viruses are hardly safe since all they need is a little sci-fi-broken-beaker-in-a-lab (which are always precariously close to a school, or mall, or even on a train...weird!) scenario to find new hosts again.
    OR, CDC just sent them the sequence, which wouldn't even invovle the CDC since they are public on GSAID.

    E.C. If they are working eukaryotic cells, then they have the machinery (Organelles like ribosomes and a ER, and maybe some polymerases and tRNAs for good measure) to make viruses. Cells don't 'learn' how since the cell is hi-jacked by the virus anyways. The cells have no choice in the matter.

    Is this a baculovirus were talking about?
  • Ottawa Guy
    1- the flu in 1918 continued to circulate in the Northern Hemisphere and the second wave need not have arisen from the Southern Hemisphere, it could have easily have been "homegrown".

    2- 20 to 50 million lives seem on the low end of current estimates

    3- virus aren't alive, they have no metabolism, so they can't be "dead"

    4- by genetic information, they mean RNA, right?

    Extra Credit:

    Since when do cells learn to propogate viruses?
  • David
    Well, for starters - as you've stated many times - viruses are not killed, they're inactivated.
  • Raj
    Immune response/ immunological defense generated by a vaccine derived from a single gene is very limited: as mentioned if the virus mutates, and mutation happens to be on that gene(HA in this case) the immune defense towards mutated virus is very limited or almost none. I would not say a "dead" virus rather inactive virus which was used to extract genetic information. Based on this information HA gene was mapped on baculovirus and infected in insect cells. I think immune defense generated by vaccine towards multiple viral proteins is much effective than targeting a single protein which can easily mutate and change epitope.

    I think the last statement is irrelevant because for vaccine production they are not propagating flu virus in insect cells rather baculovirus with HA gene which propagates efficiently in insect cell line. About safety, although baculoviruses are not known to replicate in mammalian cells, purity of HA protein in the vaccine will determine cross protection towards baculovirus.
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