[Opinion] PLA’s Biowarfare Textbook Explained – Chapter 5

Author: Billwilliam Reviewer: Irene

This is a summary of chapter 5 of the PLA’s biowarfare textbook “The Unnatural Origin of SARS-1 and the Man-made Human Virus as a Genetic Bioweapon“. This chapter presents some of the evidence why the PLA authors believed SARS-1 is of unnatural origin and is probably a man-made bioweapon.

Chapter 5 Why SARS-1 Disappeared in Nature and Among the Human Population

SARS-1 is unnatural in origin

Masked palm civets (Paguma larvata) might be sources spreading the SARS-1 virus, but they are not the natural reservoir host of this disease. After the epidemic is over, the SARS-1 virus has never been isolated in the civet cats again. SARS-1 is not a natural-focal disease because neither its direct ancestor nor reservoir host has been found.

A zoonotic pathogen usually must evolve for a long time to be able to infect humans, and its infectivity isn’t strong in the beginning. The pathogen has to undergo further evolution to adapt to humans. So, a disease of natural origin should progress from low infectivity (but maybe high mortality) to higher infectivity over years. Yet the SARS-1 outbreak isn’t compatible with the patterns of natural evolution. The book affirmed on page 136, “The SARS-1 epidemic doesn’t fit with the patterns of natural evolution. It spread quickly by human-human transmission through routes like close contacts and airborne droplets (or even limited air transmission). It spread to 29 countries and areas across the globe in months; yet more than a year later, SARS-1 disappeared from nature and among the human population. Therefore, SARS-1 isn’t a natural-focal disease; this meaning further demonstrates that SARS-1 entered the human population by an unnatural route.” The original Chinese text is shown below.

Comparison of SARS-1 with other diseases from bats

The Ebola virus has a high mortality rate; it probably jumped from bats to primates and then to humans because some people in Africa consumed bushmeat. There have been many Ebola outbreaks since its first appearance in Congo. Another virus MERS also has a high mortality rate and limited human-human transmission. Many of the MERS patients had previous contacts with camels. There are several outbreaks of MERS. (pages 137-141)

SARS-1, unlike the other two viruses, spreads efficiently by human-human transmission. It is unnatural because it has no reservoir in nature. Therefore, it disappeared after just one outbreak. The SARS-1 virus also became weakened by reverse evolution because it is not adapted to infect humans.

There are several abnormalities in the SARS-1 outbreak.

  1. Only civet cats sold in two wet markets in Guangdong tested positive for the virus, whereas civet cats from other provinces tested negative. Even if civet cats can contract the virus, they are not its natural host. (page 141)
  2. The SARS-1 outbreak disappeared after one year since it has no reservoir host. MERS, in comparison, has reservoir hosts among local camels and bats.
  3. SARS-1 is three times more infectious than MERS but has a lower mortality rate. An emerging pathogen should have low infectivity (but high mortality) at first because it is not adapted to infect humans. The high infectivity of SARS-1 is abnormal. (page 142)

Phylogenetic study

According to the textbook, Ziad Memish and his group constructed a maximum likelihood phylogenetic tree on MERS by RNA sequences. Several human MERS strains were compared with a highly homologous bat coronavirus (KSA-287-Taphozous perforatus bat)1. The phylogenetic tree supported the hypothesis that MERS is related to the bat coronavirus at 88% confidence1. MERS probably originated from nature. (page 143)

In contrast, when the textbook’s authors repeated the same phylogenetic tree analysis on SARS-1, there is only 26% confidence in the hypothesis that SARS-1 is related to a homologous SARS-like bat coronavirus (Bt-SL CoV). Therefore, SARS-1 has no credible direct ancestor. Because SARS-1 is unnatural in origin, it is not adapted to infect humans and cannot spread for long among the human population. (page 145)

Comparing SARS-1 to smallpox

Smallpox (variola virus) was eradicated for several reasons: 1) Humans are the smallpox virus’s only host and reservoir; 2) All infections display symptoms, so diagnosis is easy; 3) Those who recovered from smallpox acquire immunity; 4) The smallpox virus rarely mutates, and there are effective vaccines. (pages 147-148)

However, the disappearance of SARS-1 is abnormal. Why did it disappear after just one outbreak? Other viruses like the H5N1 avian flu have caused several outbreaks in recent years. The authors asserted that SARS-1 is a man-made passenger-type bioweapon. 

The book said on pages 145-146: “Here the ‘unnatural evolution’, by its name, means it’s ‘artificial’. That means modifying a wild animal (bat) virus [in this case, Bt SL CoV Rp3 (DQ071615) strain or a similar strain] by the published methods described in chapter 4. Using gene editing in labs along with serial passage or adaptive trials in animal models similar to humans could modify a virus into a novel species that can infect and spread among the human population (the novel species refers to SARS-1).” The original Chinese text is shown below.       


The PLA authors did present evidence why SARS-1 is an unnatural virus, but their assertion is quite bizarre. Even if SARS-1 is an artificial virus, how do they know it was modified by the techniques for developing bioweapons, as described in chapter 4? How do they know serial passage was done on the SARS-1? Has Communist China ever done serial passage to enhance bioweapons?


“Middle East Respiratory Syndrome Coronavirus in Bats, Saudi Arabia”, Memish, Z., and et al., Emerging Infectious Diseases, 2013, 19(11): 1819-1823

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15 days ago

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15 days ago

“” Has Communist China ever done serial passage to enhance bioweapons?””
This is a rhetorical question, right?