Q14 - By Michelle Hoile

If you were the scientific advisor to a friendly government, fighting Dr Evil, (fictional leader with plans for world domination), which single bioweapon would you recommend your government be most worried of?

I chose, variole virus, the causative agent of Smallpox

Here are some reasons why it’s the greatest threat:

Routine smallpox vaccination ceased more than 20years ago after WHO declared its eradication-thus most people are susceptible

Vaccine not available in Australia

It is classed as a type A bioweapon by the CDC-meaning its one of the most lethal

Viral stocks were all destroyed in 2002 (organised by WHO) although “rogue nations” and terrorists are suspected of having secret stores of the virus- thus is likely to be in the hands of Dr Evil

Has a small infectious dose of 10-100 particles

High levels of airborne person to person transmission

The symptoms of smallpox are likely to be mistaken for chicken pox because they are so similar in presentation

Standard lab pathology tests can’t differentiate between small pox and chicken pox

The two points above indicate that the virus is more likely to spread between people due to the prolonged time of detection

Its very stable in the environment, therefore increased likelihood of transmission to more people

Lethal versions of small pox are easy to make e.g. accidental creation of a lethal version of a normally mild mouse small pox virus showed this.

Variole virus can potentially become lethal after the insertion of a gene such as that for IL-4

Virulence factors can be added to its genome, making it resistant to current vaccines e.g. addition of the botox gene

Killed 400, 000 people p/a in the 18th century (Wiki)- if vaccine resistant form made in this era we could also expect high mortality rates

Mortality Variola major is 20-50% (which is already quite high) and would be even higher is more virulent mutant forms are made

A few comparisons between other diseases (See table in lecture notes book Module 8B p19)- I feel that overall the variole virus is better at causing mass destruction than the other likely candidates

ex1. Unlike the causative agent of Brucellosis, Variole is not water borne, making it a bigger problem in developed countries (Mr Evil’s probably more concerned about attacking developed countries because it is what is more likely coming between him and world domination)

ex2. Although much more lethal, anthrax is not transmitted between people and it is difficult to infect a large number of people at once. (Thus, not advantageous for world domination) Also, anthrax spores tend to clump, and when this occurs it can’t be inhaled, and can’t cause infection. Thus small pox is better at infecting a larger number of people.

See the table for more comparisons