Warning and Link to Worthwhile Read

I should mention, it may be a while until my next real post, because I'm working a big one. Maybe not big as in long, but as in the amount of work that's going into it. It's a real issue. So you can look forward to it, at least.

In the meantime, check out this well-written anecdote about a person that embodies (in a good way) pretty much all that is wrong with the anti-vaccine movement.

039 - Antipneumococcic Immunity Reactions in Individuals of Different Ages

A bit different today, not exactly about vaccines, but related: this study is concerned with immunity to pneumococcus and how that may change with a person’s age.¹

Sutliff and Finland, the study’s authors, tested the immunity of 134 subjects between the ages of 0 and 83 (some had just been born). They did a number of tests to determine immune responses to three types of pneumococcus (I, II, and III) or against pneumococcus as a whole species. These tests included analyzing the ability of blood to kill the bacteria or to protect mice against infection, and skin reaction tests when inoculated with type-specific polysaccharides or species-specific proteins or other cell contents.

Subjects were tested in hospitals, though for conditions unrelated to respiratory infection. Infants up to 2 were mostly not sick at all, just there for feeding. From 2-6 years, subjects were usually recovering from diphtheria or scarlet fever.

Sutliff and Finland found that, consistently through all type-specific tests, infants up to a couple weeks old had antibodies against all three types of pneumococcus (though most against type II and least against type I), but this immunity disappeared by 3-5 weeks after birth. Interestingly, whether a given infant had antibodies or not correlated very well with the immune status of their mother—if the mother had antibodies, chances are the infant did too, for a couple weeks.

Beyond 3-5 weeks, the proportion of subjects with antibodies gradually grew, so that by 2-11 years it was back up to the same level as among newborns. It did fall somewhat with advanced age though.

The species-specific tests didn’t seem to have any interesting pattern; they just increased as age increased.

So it seems that mothers can transfer their immunity to their offspring, at least to some extent for a short time after birth! Possibly through the placenta, if no other way. But this immunity fades, leaving infants susceptible—and indeed, the groups most susceptible to pneumonia were infants and the elderly.

It wasn’t really clear why immunity increased with age, since the subjects had never had pneumonia; possibly the subjects were exposed to some extent but not enough to become sick, or possibly they were asymptomatic carriers of pneumococcus. It was inconclusive.

Later studies citing this one had some interesting comments. Many interpreted Sutliff and Finland’s results as evidence that infants and young children don’t produce antibodies in response to pneumococcal exposure, which has obvious implications for vaccination efforts.^2–5 (Several other studies support this conclusion.)

Other comments:

 "Although earlier investigators had suggested that pneumococcal antibody declines with advancing years [039, this study], our studies showed an equal prevalence of IgG to PPS in our middle and elderly groups, probably reflecting the dynamic interaction of continued reexposure to S. pneumoniae and cumulative life experience, on the one hand, and antibody attrition together with a possible decline in antibody-forming capacity with aging, on the other."⁶

 "Invasive diseases caused by encapsulated bacteria including...pneumococci occur with highest frequency in infants and children after the decline of maternally derived antibodies."⁷

 "Sutliff & Finland state that immune bodies to the pneumococcus are present in the blood of infants immediately after birth and disappear about the end of the first month. These early type-specific antibodies are similar to those of the mothers, and are probably acquired by placental transmission."⁸

Citations:

1.  Sutliff, W. D. & Finland, M. Antipneumococcic Immunity Reactions in Individuals of Different Ages. J. Exp. Med. 55, 837–852 (1932).

2.  Weintraub, A. Immunology of bacterial polysaccharide antigens. Carbohydr. Res. 338, 2539–2547 (2003).

3.  Lindberg, A. A. Glycoprotein conjugate vaccines. Vaccine 17, Supplement 2, S28–S36 (1999).

4.  Lindberg, A. A. Polyosides (encapsulated bacteria). Comptes Rendus Académie Sci. - Ser. III - Sci. Vie 322, 925–932 (1999).

5.  Prevention of pneumococcal disease in sickle cell anemia. J. Pediatr. 129, 788–789 (1996).

6.  Musher, D. M. et al. Antibody to Capsular Polysaccharides of Streptococcus pneumoniae: Prevalence, Persistence, and Response to Revaccination. Clin. Infect. Dis. 17, 66–73 (1993).

7.  Schneerson, R. et al. Serum antibody responses of juvenile and infant rhesus monkeys injected with Haemophilus influenzae type b and pneumococcus type 6A capsular polysaccharide-protein conjugates. Infect. Immun. 45, 582–591 (1984).

8.  Guthrie, K. J. & Montgomery, G. L. Seven-Year Study of Pneumococcus Type Incidence in the Royal Hospital for Sick Children, Glasgow. J. Hyg. (Lond.) 46, 123–128 (1948).

038 - Immunization Against Vaccinia by Non-Infective Mixtures of Virus and Immune Serum

So about smallpox again. Obviously in full-blown smallpox, the skin lesions (see here) can cause some unsightly scarring. But even with the vaccine, an infection of cowpox/vaccinia virus can cause a few lesions and scars where it is inoculated into the skin, and this may not be ideal. So people wanted to see if they could improve the process and prevent this scarring.

One idea going around was, instead of using active virus by itself, mix it with serum from something already immunized with it, which would contain anti-vaccinia antibodies. This could prevent the virus from causing too bad an infection, while still allowing it to induce a good immune response.

So that's what today's study attempted.¹ C.P. Rhoads immunized 10 rabbits plus another 4 and with a mixture of vaccinia virus and serum from other rabbits that had been infected with vaccinia previously, so it was full of antibodies. Some other rabbits were kept un-vaccinated as negative controls.

Another interesting thing was that the test rabbits were inoculated by putting the mixture in their nose, rather than scraping it into the skin as usual. This was an unusual approach, so they had other rabbits inoculated in the skin the normal way as positive controls.

None of the rabbits immunized with the mixture had a negative reaction against the vaccine. Another rabbit got a vaccine of pure virus, no antibodies mixed in, and it produced the typical lesion that the virus makes.

So then the rabbits were challenged with the virus, and as expected, the negative controls produced the typical lesion that lasted a few weeks, but those immunized with mixtures previously only showed a small red spot that went away in 2 days.

Overall, the rabbits that received the mixture seemed to have good protection without a problematic response to the vaccine. Rhoads mentioned that it was important to have the correct proportions in the mixture though: too much serum and the vaccine wouldn't work well, but too little and the virus would form lesions as it normally did. Also, storing the mixture in a refrigerator was no good, since the virus escaped from the antibodies' clutches and wreaked its typical havoc.

Overall it seems interesting, but perhaps not very useful, especially if long-term storage isn't possible. And according to later studies, it might've been a misinterpretation somehow:

"The present work shows that a typical delayed hypersensitivity reaction in the absence of circulating antibody can be produced against vaccinia virus... Similar observations had been made in 1931 by Rhoads... The interpretation of his experiments was not clear at the time."²

Citations:
1. Rhoads, C. P. Immunization Against Vaccinia by Non-Infective Mixtures of Virus and Immune Serum. J Exp Med 53, 185–193 (1931).
2. Turk, J. L., Allison, A. C. & Oxman, M. N. Delayed Hypersensitivity in Relation to Vaccination and Multiplication of Vaccinia Virus in the Guineapig. The Lancet 279, 405–407 (1962).

037 - Relation of Vaccinal Immunity to the Persistence of the Virus in Rabbits

I once heard a claim from an anti-vaccine proponent that immunity from vaccines, instead of clearing the pathogen from the body the way the immune system does in the course of a “natural” infection, instead forces pathogens such as the measles virus to remain latent in cells, hiding in our bodies in an invisible state, until such time as our immunity might wane and they can be released to cause havoc. While I don’t think this claim was well-supported by any evidence, my encountering it did cause the current study to pique my interest.¹ It may not be very satisfying to my curiosity about the above claim though.

Some background: what was apparently a new technology, important at the time and foundational for this study, was electrophoresis (called cataphoresis by the authors Olitsky and Long): this technique, still used today mostly for separating all the proteins or nucleic acids in a sample based on their size, involves putting the sample into a gel immersed in a buffer full of electrolytes, and then running an electric charge from one side of the gel to the other. Since proteins and nucleic acids have an ionic charge, the current will pull them to one electrode or the other, depending on their charge. The larger ones get caught and stuck more as they’re pulled through the gel, so they move more slowly, while smaller ones can fit through smaller spaces, so they move more quickly.

In this study, though, their samples were whole viruses, rather than individual proteins or nucleic acids. People were trying electrophoresis on all kinds of different pathogens (viruses, but also protozoan parasites and virus-like bacteria^2–5) to see whether they moved toward the anode or the cathode. The technique herein was used to isolate and concentrate virus from animal tissues, virus that was too scarce to be detected by other methods (at the time). I should mention that in any case, “detection” of the virus involved inoculating other rabbits with the sample and seeing if they produced a characteristic infection reaction. It wasn’t good to be a rabbit in that lab in those days.

The hypothesis Olitsky and Long were testing was based on previous observations by others, that viruses could be detected in animal’s (and sometimes human’s) tissues longer after that organism had recovered from the viral illness. For example, polio virus had been detected from an infected monkey and a person several months after they had recovered. The authors speculated that immunity to a virus depends on the persistent presence of that virus in an animal’s tissues; after the virus is completely gone, the animal is no longer immune. (This observation and hypothesis didn’t distinguish between a “natural” infection or a live attenuated immunization, such as vaccinia inoculation as a vaccine against smallpox, so it wouldn’t support the anti-vaccine claim above in any case.)

Their model for this study was vaccinia (cowpox) virus infecting the testicles of rabbits. They took rabbits that had been infected at various times past, from 12 to 133 days previous to the study, and recovered. Samples of these animals’ tissues were taken under anesthesia, keeping the animals alive so they could be tested for immunity later, and electrophoresis was used to detect virus in the tissue samples. Olitsky and Long detected virus in samples from each of these rabbits, even the one infected more than 4 months before. (Note of contention: I don’t think they had any negative controls to make sure they weren’t just detecting contamination or something.)

Then the authors took five more rabbits that had recovered from viral infection 119 to 183 days before and tested them for virus. They took samples, seemingly randomly, from spleen, testicles, and skin, and checked for virus using electrophoresis. In the rabbits infected earlier, no virus was isolated, and they appeared to have lost their immunity; in those infected later, the authors did detect virus, and the rabbits seemed immune. So they concluded that the persistent presence of virus was necessary for immunity.

The next step was based on another previous finding that immunity seemed to be transmissible from mother to offspring. This was based on some observation of a pregnant mother and her newborn, and some preliminary animal study. So Olitsky and Long tested this hypothesis in two pregnant rabbits, one infected soon before giving birth, and the other infected but given time to recover before birth. The former’s offspring seemed immune, and electrophoresis recovered virus from the testicles of a male baby rabbit; but the latter’s offspring seemed susceptible to infection as normal. So the conclusion was that immunity (and persistent infection) is heritable only when the mother is infected at the time of birth.

These are interesting results, but the quality of evidence seems pretty low. There weren’t very good controls, and the sample sizes were quite small. Also it is in rabbits, which isn’t necessarily a good model animal. This poor quality seems borne out by later studies, some by the same researchers, that contradicted or found better explanations for these results:

"By the means employed in this investigation, vaccinal immunity has been shown to endure beyond the persistence of recoverable virus."⁶ (Similar results in other studies^7,8)

"Whatever the detailed mechanism, it is evident in our study that newborn rabbits have been made tolerant immunologically toward the antigens of vaccinia virus for at least a relatively brief period. Perhaps tolerance also explains the early observations of Olitsky and Long [037, this study] made on a single pregnant rabbit and its 3 offspring."⁹

References:

1.  Olitsky, P. K. & Long, P. H. Relation of Vaccinal Immunity to the Persistence of the Virus in Rabbits. J. Exp. Med. 50, 263–272 (1929).

2.  Olitsky, P. K., Rhoads, C. P. & Long, P. H. The Effect of Cataphoresis on Poliomyelitis Virus. J. Exp. Med. 50, 273–277 (1929).

3.  Kligler, I. J. Recovery of Fowl-pox Virus from Vaccines by Cataphoresis. Br. J. Exp. Pathol. 12, 42 (1931).

4.  Kligler, I. J. & Olitzki, L. Cataphoresis Experiments with Typhus Virus. Br. J. Exp. Pathol. 12, 69 (1931).

5.  Salle, A. J. The Electrical Behavior of Leishmania donovani. J. Infect. Dis. 49, 450–454 (1931).

6.  Morgan, I. M. & Olitsky, P. K. A Study of Immunity in Rabbits from Two to Three Years After Infection with Vaccine Virus with Attempts to Recover Active Virus. J. Immunol. 39, 1–15 (1940).

7.  Pearce, J. M. The Persistence of Vaccine Virus in Rabbits Immunized to Vaccinia by a Previous Infection and the Relationship of Immunity to Latent Virus. J. Infect. Dis. 66, 130–137 (1940).

8.  Olitsky, P. K. & Casals, J. Concepts of the Immunology of Certain Virus Infections. Bull. N. Y. Acad. Med. 21, 356 (1945).

9.  Flick, J. A. & Pincus, W. B. Inhibition of the Lesions of Primary Vaccinia and of Delayed Hypersensitivity Through Immunological Tolerance in Rabbits. J. Exp. Med. 117, 633–646 (1963).