Reply To: A Hello to Virology
(I’ve replaced the deprecated term “millimicrons” and its units with “nanometers”, nm, which are equivalent and represent billionths of a meter.)
“Particle Size of the Virus: The diameter of the virus as determined by filtration of highly infectious human serum through gradocol membranes was estimated at 12 to 25 millimicrons [nm], because all the volunteers who received the filtrates from membranes with an average pore diameter (A. P. D.) of 75 [nm] or greater developed typically severe dengue, while 2 volunteers who received the filtrate from the membrane with an A. P. D. of 50 [nm] remained well. However, since the latter volunteers exhibited a partial immunity to reinoculation several
months later, it is possible that approximately one M. I. D. [minimal infective dose] of virus might have passed the 50 [nm] membrane, and that the virus may actually be somewhat smaller than 17 to 25 [nm].The virus could be sedimented from human serum by centrifugation at 24,000 r.p.m. for 90 minutes in an 8-inch rotor of a vacuum ultracentrifuge. Examination with the electron microscope of preparations from highly infectious human dengue serum, purified by differential centrifugation, revealed dumb-bell-shaped structures (700 [nm] x 20-40 [nm]), which were not found in similar preparations from normal human serum.”
Unfortunately, there are no micrographs presented in the paper, and we’ll never know exactly what Sabin and his colleagues found here. The virions to be described later are around 50 nm, alright, but what the “dumb-bell-shaped structures” were will likely remain a mystery. Possibly, there were problems with sample preparation (perhaps there were artifacts resulting from the purification process), as electron microscopy applied to viruses was still in its infancy.
Also of note from this paper the adaptation of dengue virus to mice. In short, mice are injected with dengue and further virus is extracted from those who are found to be susceptible. This continues for many iterations or “passages” until most mice are found to be susceptible (having severe symptoms).
“Extracts of the brain and spinal cord of paralyzed mice, derived from the first 6 consecutive
passages in mice, upon inoculation in human volunteers produced clinical manifestations of varying severity – relatively mild in some and fully severe and unmodified in others…. Beginning with the seventh passage in mice, however, the virus had lost its capacity to produce the severe illness and protracted fever, characteristic of the unmodified disease in human beings, but retained its capacity to produce a rash and solid immunity to the unmodified virus.”
I.e. mouse-adapted dengue virus. This becomes important because now there is an animal which can be used to propagate and study the virus.
You’ll find that human volunteers become a rarity as studies move further from the military realm (as in this case and in earlier papers) and, in my opinion, the litigiousness of society increases. That said, the volunteers for these studies had cajones grandes, as dengue can be an excruciating and horrifying experience.
The next couple of papers presented should complete the re quest for studies “showing that the alleged particle exists and causes the disease that it’s alleged to cause” and “describing the purification of particles that are alleged to be said virus(es), directly from bodily fluid/tissue/excrement, with purification confirmed via EM imaging (the images must be available as well).”
The tissue may be the brain tissue of mice, but the virus is dengue, even if adapted to mice. The virus most assuredly causes disease in the infected mice, and the brains of such mice are found to have high titers (concentrations) of virus.
The virus used in the following papers was the New Guinea “C” strain of dengue-2.