Бустер в нос?

[chuka_lis]

Одобренные в настоящее время  вакцины вызывают системный иммунитет, но в слизистой носа и тд, иммунитет оказывается слабый (можно заразиться и передать).
Исследователи из Йейля разработали новую вакцину, Prime and Spike, и методику, основанную на неадъювантной интраназальной стимуляции имунитета после праймирования (1 доза внутримышечно). Prime и Spike содержит  микс из шипиков коронавирусов с разными антигенами или их мРНК (unadjuvanted spike protein or an immunosilent polyplex encapsulating mRNA), без адьюванта (тк есть мнение, что адьюванты в спреях могут стимулировать воспаление, чересчур).
Такая бустерная прививка "через слизистую"  использует существующий иммунитет, созданный первичной прививкой, для стимуляции иммунной памяти слизистой оболочки дыхательных путей (и легких в том числе).
В доклиническом исследовании показано, что  бустерная доза их вакцины в нос (спрей) индуцируют актвиацию Т- и В-резидентных  клеток  памяти, и выработкуи IgA в слизистой оболочке дыхательных путей. Кроме этого, она повышает и  системный иммунитет (и клеточный и гуморальный).
Однако, сами по себе, что внутримышечная, что интраназальная, прививки не работают хорошо. А вот в комплексе,  их вакцина (1 доза в мышцу, 2 -в нос) у мышей, на 100% защищала животных от летального ковида. Авторы считают, что таким образом формируется  хороший перекрестно-реактивный иммунитет против сарбековирусов (и штаммов ковида, и даже САРС), причем без подключения импритинга.
Ну, это в приницпе, то же самое, что сначала привиться, а потом заболеть (тк вирус попадает через слизистую дыхательных путей, и ее же стимулирует).
Так что их  способ подкрепляет идею, что те, кто привился а потом столкнулся с вирусом в ВДП, защищены получше, чем просто привитые- тк, будет усиливаться иммунитет не только системный, но и в слизистой. Без прививки же, системный иммунитет может и не вырасти до уровня, когда будет защищать. А без стимулирования слизистой- там он будет слабенький.
Но, если этот подход окажется рабочим не только на мышах, это более обещающий вариант. Главное, чтоб побочек было поменьше, и эффективность от реинфекции спустя время, тоже проверили. В том числе и от "штаммов".
Currently approved SARS-CoV-2 mRNA-LNP-based and vector-based vaccines rely on intramuscular administration, which induces high levels of circulating antibodies, memory B cells and circulating effector CD4+ and CD8+ T cells in animal models and humans (12-14). However, parenteral vaccines do not induce high levels of potent antiviral immune memory at sites of infection such as tissue resident memory T cells (TRM) and B cells (BRM) as well as mucosal IgG and dimeric IgA (15-17). This is in contrast to SARS-CoV-2 infection in humans and mice where CD8+ TRM are robustly induced (15, 18). Vaccines targeting the respiratory mucosa could address the shortcomings of parenteral vaccination, as recent preclinical assessments of intranasally delivered SARS-CoV-2 spike encoding adenoviral vectors have shown impressive mucosal immunogenicity as well as protection and reduced viral shedding in mice, hamsters, and nonhuman primates (19-23). Preclinical mucosal influenza vaccine studies have also shown that mucosal immunity can enhance protection against heterosubtypic challenge via CD8+ TRM or dimeric IgA and may improve durability of immunity (24, 25). While primary respiratory administration of vaccines induces potent mucosal immune responses, some studies have shown that priming systemically followed by intranasal boosting results in similar systemic immunity to systemic prime and boost regimens, but with the added benefit of enhanced mucosal immunity (26, 27). Most recombinant subunit vaccines administered via systemic priming followed by intranasal boosting or intranasal prime and boost require adjuvants to enhance immunogenicity. However, administration of vaccines to the respiratory tract in humans has proven difficult as vaccine associated adverse events within the respiratory tract are typically less tolerated than with systemic administration. Additionally, there have been cases of intranasal adjuvanted inactivated vaccine for seasonal influenza leading to non-respiratory adverse events (Bell’s palsy) in patients, which was hypothesized to be caused by adjuvant-mediated inflammation (28). In the setting of waning immunity from parenteral vaccination regimens we assessed the immunogenicity and protection afforded by intranasal boosting (IN) SARS-CoV-2 spike. Here we describe a vaccination strategy that utilizes the strong systemic priming of mRNA-LNP based vaccine followed by IN boosting with either unadjuvanted spike protein or an immunosilent polyplex encapsulating mRNA in a preclinical model of COVID-19. To assess the potential of IN unadjuvanted subunit vaccine boosting for the development of respiratory tract mucosal immunity, we decided to harness the strong systemic immunogenicity of mRNA-LNP. We additionally benefited from extensive SARS-CoV-2 spike engineering which helps stabilize the protein in its prefusion confirmation with the addition of a C-terminal T4 fibritin trimerization motif, six proline substitutions (F817P, A892P, A899P, A942P, K986P, V987P), and alanine substitutions (R683A and R685A) in the furin cleavage site (29). These sets of mutations have been shown to significantly enhance immunogenicity and increase protein stability, some of which are used in current vaccines. We vaccinated K18-hACE2 mice with 1 μg of mRNA-LNP (Comirnaty) by IM injection (Prime), followed 14 days later by 1 μg of recombinant unadjuvanted spike protein by IN administration (Prime and Spike). Additional control groups include K18-hACE2 mice that received IM Prime only and mice that received IN spike only at boosting. Mice were euthanized at day 21 or 28 (7- or 14-days post boosting) and assessed for the development of mucosal humoral immunity. The experiments above clearly demonstrate that boosting at a distinct anatomic location, in this case the respiratory mucosa, either by unadjuvanted subunit spike or by PACE-Spike encoding spike, enables the formation of new mucosal immune memory at the newly boosted site and enhances systemic immunity to that antigen. In both unadjuvanted subunit spike and mRNAPACE, the boosting antigen is homologous to the systemic priming antigen (mRNA-LNP). Current circulating strains of SARS-CoV-2, notably Delta and Omicron, have significant changes to the spike protein sequence and structure. Delta harbors T19R, G142D, Δ156-157, R158G, Δ213-214, L452R, T478K, D614G, P681R, and D950N mutations, whereas Omicron harbors A67V, Δ69-70, T95I, G142D, Δ143-145, N211I, L212V, ins213-214RE, V215P, R216E, G339D, S371L, S373P, S375F, K417N, N440K, G446S, S477N, T478K, E484A, Q493R, G496S, Q498R, N501Y, Y505H, T547K, D614G, H655Y, N679K, P681H, N764K, D796Y, N856K, Q954H, N969K, and L981F mutations. These mutations have made both Delta and Omicron transmit more rapidly and evade pre-existing humoral immunity, and it is likely that future variants will diverge even more, suggesting a boosting strategy that elicits broadly reactive immunity will be necessary to neutralize future variants.these data indicate that IN boosting with unadjuvanted heterologous spike protein can induce potent mucosal cellular and humoral memory against significantly divergent spike protein in the absence of original antigenic sin. Here we describe the preclinical development of a new vaccine strategy, Prime and Spike, where IN unadjuvanted spike subunit protein can elicit robust protective mucosal immunity following mRNA-LNP parenteral immunization. Prime and Spike elicited robust mucosal cellular and humoral memory responses including the establishment of CD8+ TRM, CD4+ TRM, BRM, IgA, and IgG. We found that an IN unadjuvanted spike booster can be administered months out from primary immunization, and that it offers comparable systemic neutralizing antibody responses to mRNA-LNP boost, with the added benefit of mucosal immunity. Similarly, we find that IN boosting with mRNA encapsulated in PACE polymers (Prime and PACE-Spike) elicits increased mucosal CD8+ TRM and IgA. Both boosting methods resulted in protection from lethal SARSCoV- 2 challenge in a mouse model of waning immunity. Finally, by utilizing a divergent spike antigen, we demonstrate that Prime and SpikeX can generate mucosal immunity to SARS-CoV- 1, while also boosting the neutralizing antibodies to the original antigenic target, SARS-CoV-2 spike. While the goal of vaccination has been to prevent individual morbidity and mortality, the evolution of SARS-CoV-2 throughout the pandemic has highlighted the need for rapidly deployable mucosal vaccines which not only protect the individual, but also prevent transmission. mRNA-LNP based vaccines initially showed incredible efficacy (~95%) against severe disease as well as reduced transmission; however, waning immunity, viral immune evasion, and increased viral transmissibility have demonstrated their limits in current form. Specifically, these and other currently approved SARS-CoV-2 vaccines induce little mucosal immunity in the respiratory tract (15-17), the site of infection and transmission. Our data demonstrated that Prime and Spike significantly reduced the viral load in the nasal cavity and the lung compared to parenteral vaccine alone, indicating the promise of Prime and Spike in reducing infection and transmission. Improving upon current vaccine platforms to provide mucosal immunity is important to curb this current pandemic, and certainly will be important to combat the next. Preclinical studies of both SARS-CoV-2 and Influenza have demonstrated that intranasal vaccination decreases viral shedding and transmission relative to parenteral vaccines (19-23). Despite these studies, there is only one currently approved respiratory mucosal vaccine, Flumist, which relies on a live cold-adapted influenza virus. While this is an effective and wellstudied technology, it is contraindicated in people with underlying respiratory conditions, is only approved for the young, and is not amenable to rapid implementation in the setting of an emergent respiratory virus epidemic or pandemic as they require extensive research and development. As such, all current early phase clinical trials of mucosal administered SARSCoV- 2 vaccines rely on either replication deficient or attenuated viral vectors; however, safety and efficacy are yet to be established, especially given that preexisting immunity to these vectors can lead to reduced immunogenicity (34). In fact, some vector based mucosal vaccines—including two Merck candidates V590 and V591—have already been abandoned after phase 1 clinical trials showed poor immunogenicity. This is the first report of boosting preexisting systemic immunity generated by currently approved SARS-CoV-2 vaccines (mRNA-LNP) with IN unadjuvanted spike protein to elicit robust mucosal immunity. This technology enables the use of a non-inflammatory local boost at a tissue compartment sensitive to immunological effector mechanisms such as the respiratory tract to induce mucosal and systemic immunity. We also demonstrate that IN unadjuvanted subunit boost induces CD4+ TRM, CD8+ TRM, BRM, and mucosal IgA and IgG, and challenges prior dogma suggesting that subunit vaccines cannot induce robust cellular responses and that adjuvants are required for subunit vaccines to induce respiratory mucosal immunity. Further, this is the first report to successfully and safely deliver mRNA to the respiratory tract as a SARS-CoV-2 vaccine boost utilizing a novel formulation of biodegradable, non-inflammatory PACE polymers. These technologies are likely broadly applicable to be used as boosters against new VOCs for SARS-CoV-2 or as part of a primary immunization strategy for newly emerging respiratory pathogens. While it is possible that these results rely on specific characteristics of the mRNALNP priming, we believe that this will likely work with other primary immunization regimens, or in the case of previous infection; however, this will require further assessment. Additionally, it has been shown that the highly stabilized spike enhances its immunogenicity, and that applying this novel vaccination strategy to other pathogens may require the addition of stabilizing mutation of the antigen of choice to enable unadjuvanted boosting as reported here. That said, using a less modified SARS-CoV-1 spike also enabled unadjuvanted IN boosting of a heterologous antigen. Vaccines that generate broadly neutralizing serum immunity against a wide variety of sarbecoviruses has been a recent goal to combat both newly emerging SARS-CoV-2 variants and other potential future pandemic SARS like coronaviruses. Here, we utilize SARS-CoV-1 spike as a heterologous IN boost, in Prime and SpikeX, and show that prior SARS-CoV-2 mRNA-LNP does not prevent the development of SARS-CoV-1 neutralizing antibodies, but that it likely enables it as IN Spike alone was not immunogenic. Prime and SpikeX simultaneously elicits more broadly reactive neutralizing antibodies and mucosal immunity. While some recent studies have successfully reported the development of pan-sarbecovirus vaccines (33, 35), this is the first report that we are aware of that shows the induction of both systemic and mucosal immunity against both SARS-CoV-1 and SARS-CoV-2. SARS-CoV-2 will continue to evolve and become more immune evasive and transmissible as we have seen with the Omicron VOC. We will be requiring boosting in human populations for the foreseeable future; however, boosting that induces mucosal immunity may help to enhance protection and slow transmission as these new variants emerge.