In this study, we investigated the inactivation of wild-type vMyx-GFP (MYXV) using different methods. Assays were performed in vitro to test the following inactivation methods: heat, longwave UV only, longwave UV with psoralen (P + LWUV), and psoralen (P) only. In vitro assays demonstrated that the psoralen alone treatment did not cause any inactivation. These results showed that effective inactivation using psoralen was likely reliant on subsequent UV irradiation, creating a synergistic effect. Additionally, the UV and P + LWUV treatment demonstrated inactivation of MYXV, although by different mechanisms, as the UV-only treated virus demonstrated background infection, while P + LWUV treated virus did not. In mice, P + LWUV and UV treatment of MYXV demonstrated to be effective inactivation methods and likely preserved the antigenic epitopes of MYXV, allowing for the production of neutralizing antibodies in mice. More research is recommended on the heat treatment of MYXV as neutralizing antibodies were not observed, possibly due to the treatment denaturing antigenic epitopes or needing more booster injections to reach the threshold antibody concentration for protection. Furthermore, we demonstrated that the intraperitoneal (IP) injection of inactivated MYXV was superior to the subcutaneous injection in eliciting a strong immune response. The increased neutralizing antibodies observed after IP injection could be due to the advantage that the IP route has of reaching lymphoid tissue faster.

In 2006, United States pharmaceutical company Merck released the Gardasil vaccination series, which protected recipients against four strains of Human Papillomaviruses, or HPV. HPV is a sexually transmitted infection which may be asymptomatic or cause symptoms such as genital warts, and is linked to cervical, vaginal, vulvar, anal, penile, head, neck, and face cancers. In 2006, based on research conducted by researchers Ian Frazer and Jian Zhou in the 1990s, Merck released a four-strain version of Gardasil, which protected boys and girls aged nine and older against the major HPV strains HPV-6, HPV-11, HPV-16, and HPV-18. In 2014, Merck released Gardasil 9, a nine-strain version that protected from the original four HPV strains plus strains HPV-31, HPV-33, HPV-45, and HPV-58. Gardasil is a preventative measure and reduces the risk of contracting HPV and HPV-related cancers by up to ninety-seven percent.

Ian Hector Frazer studied the human immune system and vaccines in Brisbane, Australia, and helped invent and patent the scientific process and technology behind what later became the human papillomavirus, or HPV, vaccinations. According to the Centers for Disease Control and Prevention of the US, or CDC, HPV is the most common sexually transmitted infection, and can lead to genital warts, as well as cervical, head, mouth, and neck cancers. Frazer and virologist Jian Zhou conducted research in the 1990s to assess why women with HPV had higher rates of precancerous and cancerous cervical cells. Frazer’s research led the pharmaceutical company Merck to produce the Gardasil vaccination series, and GlaxoSmithKline to produce the Cervarix vaccination. Frazer’s research contributed to the development of HPV vaccinations that have been successful in reducing up to seventy percent of cervical cancer cases in women.

Stanley Alan Plotkin developed vaccines in the United States during the mid to late twentieth century. Plotkin began his research career at the Wistar Institute in Philadelphia, Pennsylvania, where he studied the rubella virus. In pregnant women, the rubella virus caused congenital rubella syndrome in the fetus, which led to various malformations and birth defects. Using WI-38 cells, a line of cells that originated from tissues of aborted fetuses, Plotkin successfully created RA27/3, a weakened strain of the rubella virus, which he then used to develop a rubella vaccine. Plotkin’s rubella vaccine has prevented birth defects due to congenital rubella in developing fetuses and newborns.

From 1958 to 1961, Leonard Hayflick and Paul Moorhead in the US developed a way in the laboratory to cultivate strains of human cells with complete sets of chromosomes. Previously, scientists could not sustain cell cultures with cells that had two complete sets of chromosomes like normal human cells (diploid). As a result, scientists struggled to study human cell biology because there was not a reliable source of cells that represented diploid human cells. In their experiments, Hayflick and Moorhead created lasting strains of human cells that retained both complete sets of chromosomes. They then froze samples from the cultures so that the cells remained viable for future research. They also noted that cells could divide only a certain number of times before they degraded and died, a phenomenon later called the Hayflick limit. Hayflick and Moorhead’s experiment enabled research on developmental biology and vaccines that relied on human cell strains.

In 2011, United Kingdom pharmaceutical company GlaxoSmithKline released Cervarix, a vaccination series protecting girls and women from two strains of Human Papillomavirus, or HPV. HPV, a sexually transmitted infection, can present in men and women without symptoms, or may cause symptoms such as genital warts. There is a link between HPV and cervical, vaginal, anal, head, neck, and face cancers, and Cervarix can reduce genital cancers in girls and women, particularly cervical cancer. Gardasil, a similar vaccination against HPV, approved by the United States Food and Drug Administration, or FDA and available in the US in June 2006 was on the market five years prior to Cervarix’s approval in October 2009. In 2014, because of the heightened cost and lesser coverage, the US market discontinued Cervarix, but as of 2019, it remains popular in Europe, especially in the United Kingdom. Cervarix is the first HPV vaccine administered in China.

L'Institut Pasteur (The Pasteur Institute) is a non-profit private research institution founded by Louis Pasteur on 4 June 1887 in Paris, France. The Institute's research focuses on the study of infectious diseases, micro-organisms, viruses, and vaccines. As of 2014, ten scientists have received Nobel Prizes in physiology or medicine for the research they have done at the Pasteur Institute. Contrary to the way genetics was studied in US research universities during the mid-twentieth century, the genetic research conducted at the Pasteur Institute at the same time did not rest on a conceptual separation between embryology and evolution. According to historian Michel Morange from the Ecole Normale Superieure in Paris, France, this difference enabled Pasteurian scientists to develop the concepts of regulatory genes and of developmental genes.

Memory CD8+ T cells protect against secondary viral infections. They develop and maintain exclusively in circulation (e.g. central memory - Tcm) or are excluded from re-circulation (resident memory - Trm). The extracellular ATP receptor P2RX7 promotes both Tcm and Trm generation. High (P2RX7hi) P2RX7-expressing early effector cells show survival, memory and pluripotency genes. Conversely, many terminal effector (TE) and apoptosis genes are upregulated in low (P2RX7lo) P2RX7-expressing cells. Among these genes is the zinc-finger transcriptional repressor Zeb2, which promotes TE differentiation at the expense of the memory cell pool. Given that Zeb2 was higher in P2RX7lo early effector cells, we postulated that Zeb2 ablation would allow P2RX7-deficient CD8+ T cells to skew towards memory subsets. To test this, we used RNP-based CRISPR-Cas9 to knockout Zeb2 in wild type or P2RX7-deficient P14 cells. At the memory timepoint, Zeb2 ablation led to a rescue of the ability of P2RX7-deficient cells to differentiate into the CD62L+ Tcm and CD69hiCD103hi Trm subsets, as well as increase the population of each. Our data suggest that P2RX7 imprints a pro-memory signature that is, to some extent, dependent on the negative regulation of Zeb2.