Correlates of Protection
in Rhesus Macaques
Antibodies and T-cells protect against SARS-CoV-2 in monkeys.
Lactic acid inhibits the growth of several bacterial pathogens, including E. coli and S. enterica. Researchers have recently shown Lactobacillus murinus can inhibit growth of Streptococcus pneumoniae. Under healthy, eubiotic conditions, L. murinus is the dominant colonizer of the mouse lung. Researchers found that under dysbiotic conditions, addition of L. murinus can provide lung protection against intranasally acquired S. pneumoniae. This study could not demonstrate a link between lactic acid formation and inhibition of pneumococci growth. Therefor researchers hypothesize that an as yet unknown anatomical condition may be induced by commensal microbiota that prevents S. pneumoniae growth.
Immune Diagnostics' partner Pel-Freeze Biologicals presented a great webinar for The World Vaccine Congress 2020 on how their products can help support pneumococcal vaccine development in laboratory assays. See if you can find a hidden announcement from Immune Diagnostics on an upcoming product! (Hint: 18:41.)
Learning From Our Past
What can we learn from the flu pandemic of 1918 to assist us in the age of COVID19? Autopsy results and physical specimens that were newly examined by Morens, Taubenberger and Fauci (2008) show clear signs of secondary bacterial pneumonia. The authors conclude that upper respiratory illness caused by bacterial pneumonia was likely responsible for a majority of deaths during the H1N1 Spanish flu pandemic of 1918. Subsequent viral pandemics of ’57 (H2N2 influenza) and ’68 (H3N2 influenza) show similar results. Around 24% (n=96) of samples tested positive for Streptococcus pneumoniae. They also looked for presence of S. pyogenes, S. aureus, N. meningitidis, H. influenzae, and others. Of these postmortem cultures from victims of the 1918 pandemic, only 4.2% exhibited no pathogenic bacterial growth. Given the severity of COVID19 viral pneumonia, comorbidity of a bacterial pneumonia infection could increase the chance of a fatal outcome during this current pandemic. A quote from Louis Cruveilhier in 1919 summarizes succinctly: “If grippe condemns, the secondary infections execute.” It is with these data in mind that research and treatment of pneumonia-causing bacteria such as S. pneumoniae should remain at the forefront of research efforts alongside COVID19.
A recent Lancet correspondence reports on the stability of SARS-CoV-2 in different environmental
conditions. SARS-CoV-2 remains infectious at 4 °C on day 14, while exposure to heat of 70 °C inactivates the virus after 5 minutes. SARS-CoV-2 also remains stable at a wide range of pH values. “Overall, SARS-CoV-2 can be highly stable in a favourable environment, but it is also susceptible to standard disinfection methods.”
Dr. Moon Nahm’s lab has identified the 100th Streptococcus pneumoniae serotype. The new serotype 10D has been named for a its serological similarity to S. pneumoniae serotype 10A. The eternal pursuit of new serotype identification is extremely important to stay abreast of prevalent and disease-causing S. pneumoniae bacteria in any given population.
COVID19 Vaccine Development
The World Health Organization (WHO) has drafted a document of feasibility for a challenge model in COVID19 vaccine development. A challenge study involves the use of a controlled human infection model (CHIM), thus the cost-benefit of such a model is highly debated. The risk of purposeful infection (challenge) with SARS-Cov-2 must be weighed carefully, especially where a proven rescue therapy is not yet available. If current vaccine efforts fall short, the WHO document can serve as a “preparatory strategy so that if conditions are deemed appropriate, there will be a technically valid roadmap of what needs to be done to initiate a closely monitored challenge model of SARS-CoV-2 infection.”