Characterization of recombinant vaccinia viruses and their products

Mucosal IL-4R antagonist HIV vaccination with SOSIP-gp140 booster can induce high-quality cytotoxic CD4+/CD8+ T cells and humoral responses in macaques

Inducing humoral, cellular and mucosal immunity is likely to improve the effectiveness of HIV-1 vaccine strategies. Here, we tested a vaccine regimen in pigtail macaques using an intranasal (i.n.) recombinant Fowl Pox Virus (FPV)-gag pol env-IL-4R antagonist prime, intramuscular (i.m.) recombinant Modified Vaccinia Ankara Virus (MVA)-gag pol-IL-4R antagonist boost followed by an i.m SOSIP-gp140 boost. The viral vector-expressed IL-4R antagonist transiently inhibited IL-4/IL-13 signalling at the vaccination site. The SOSIP booster not only induced gp140-specific IgG, ADCC (antibody-dependent cellular cytotoxicity) and some neutralisation activity, but also bolstered the HIV-specific cellular and humoral responses. Specifically, superior sustained systemic and mucosal HIV Gag-specific poly-functional/cytotoxic CD4⁺ and CD8⁺ T cells were detected with the IL-4R antagonist adjuvanted strategy compared to the unadjuvanted control. In the systemic compartment elevated Granzyme K expression was linked to CD4⁺ T cells, whilst Granzyme B/TIA-1 to CD8⁺ T cells. In contrast, the cytotoxic marker expression by mucosal CD4⁺ and CD8⁺ T cells differed according to the mucosal compartment. This vector-based mucosal IL-4R antagonist/SOSIP booster strategy, which promotes cytotoxic mucosal CD4⁺ T cells at the first line of defence, and cytotoxic CD4⁺ and CD8⁺ T cells plus functional antibodies in the blood, may prove valuable in combating mucosal infection with HIV-1 and warrants further investigation.

Mucosal and systemic SIV-specific cytotoxic CD4+ T cell hierarchy in protection following intranasal/intramuscular recombinant pox-viral vaccination of pigtail macaques

A HIV vaccine that provides mucosal immunity is urgently needed. We evaluated an intranasal recombinant Fowlpox virus (rFPV) priming vaccine followed by intramuscular Modified Vaccinia Ankara (rMVA) booster vaccine, both expressing SIV antigens. The vaccination generated mucosal and systemic SIV-specific CD4⁺ T cell mediated immunity and was associated with partial protection against high-dose intrarectal SIV_mac251 challenge in outbred pigtail macaques. Three of 12 vaccinees were completely protected and these animals elicited sustained Gag-specific poly-functional, cytotoxic mucosal CD4⁺ T cells, complemented by systemic poly-functional CD4⁺ and CD8⁺ T cell immunity. Humoral immune responses, albeit absent in completely protected macaques, were associated with partial control of viremia in animals with relatively weaker mucosal/systemic T cell responses. Co-expression of an IL-4R antagonist by the rFPV vaccine further enhanced the breadth and cytotoxicity/poly-functionality of mucosal vaccine-specific CD4⁺ T cells. Moreover, a single FPV-gag/pol/env prime was able to induce rapid anamnestic gp140 antibody response upon SIV encounter. Collectively, our data indicated that nasal vaccination was effective at inducing robust cervico-vaginal and rectal immunity, although cytotoxic CD4⁺ T cell mediated mucosal and systemic immunity correlated strongly with 'complete protection', the different degrees of protection observed was multi-factorial.

Organism-Level Analysis of Vaccination Reveals Networks of Protection across Tissues

A fundamental challenge in immunology is to decipher the principles governing immune responses at the whole-organism scale. Here, using a comparative infection model, we observe immune signal propagation within and between organs to obtain a dynamic map of immune processes at the organism level. We uncover two inter-organ mechanisms of protective immunity mediated by soluble and cellular factors. First, analyzing ligand-receptor connectivity across tissues reveals that type I IFNs trigger a whole-body antiviral state, protecting the host within hours after skin vaccination. Second, combining parabiosis, single-cell analyses, and gene knockouts, we uncover a multi-organ web of tissue-resident memory T cells that functionally adapt to their environment to stop viral spread across the organism. These results have implications for manipulating tissue-resident memory T cells through vaccination and open up new lines of inquiry for the analysis of immune responses at the organism level.

A novel target and approach for identifying antivirals against molluscum contagiosum virus

The dermatological disease molluscum contagiosum (MC) presents as lesions restricted solely to the skin. The poxvirus molluscum contagiosum virus (MCV) is responsible for this skin disease that is easily transmitted through casual contact among all populations, with greater frequency in children and immunosuppressed individuals. In addition, sexual transmission of MCV in adolescents and adults is a health concern. Although the skin lesions ultimately resolve in immunocompetent individuals, they can persist for extended periods, be painful, and result in scarring. Treatment is problematic, and there is no drug that specifically targets MCV. The inability of MCV to propagate in cell culture has impeded drug development. To overcome these barriers, we integrated three new developments. First, we identified a new MCV drug target (mD4) that is essential for processive DNA synthesis in vitro. Second, we discovered a small chemical compound that binds to mD4 and prevents DNA synthesis in vitro. Third, and most significant, we engineered a hybrid vaccinia virus (mD4-VV) in which the natural vaccinia D4 (vD4) gene is replaced by the mD4 target gene. This hybrid virus is dependent on mD4 for viral growth in culture and is inhibited by the small compound. This target system provides, for the first time, a platform and approach for the discovery and evaluation of new therapeutics that can be used to treat MC.