A Herpes Simplex Virus Type 2 Deleted for Glycoprotein D Enables Dendritic Cells to Activate CD4+ and CD8+ T Cells.

Herpes simplex virus type 2 (HSV-2) is highly prevalent in the human population producing significant morbidity, mainly because of the generation of genital ulcers and neonatal encephalitis. Additionally, HSV-2 infection significantly increases the susceptibility of the host to acquire HIV and promotes the shedding of the latter in the coinfected. Despite numerous efforts to create a vaccine against HSV-2, no licensed vaccines are currently available. A long-standing strategy, based on few viral glycoproteins combined with adjuvants, recently displayed poor results in a Phase III clinical study fueling exploration on the development of mutant HSV viruses that are attenuated in vivo and elicit protective adaptive immune components, such as antiviral antibodies and T cells. Importantly, such specialized antiviral immune components are likely induced and modulated by dendritic cells, professional antigen presenting cells that process viral antigens and present them to T cells. However, HSV interferes with several functions of DCs and ultimately induces their death. Here, we propose that for an attenuated mutant virus to confer protective immunity against HSV in vivo based on adaptive immune components, such virus should also be attenuated in dendritic cells to promote a robust and effective antiviral response. We provide a background framework for this idea, considerations, as well as the means to assess this hypothesis. Addressing this hypothesis may provide valuable insights for the development of novel, safe, and effective vaccines against herpes simplex viruses.

Evasion of early antiviral responses by herpes simplex viruses.

Besides overcoming physical constraints, such as extreme temperatures, reduced humidity, elevated pressure, and natural predators, human pathogens further need to overcome an arsenal of antimicrobial components evolved by the host to limit infection, replication and optimally, reinfection. Herpes simplex virus-1 (HSV-1) and herpes simplex virus-2 (HSV-2) infect humans at a high frequency and persist within the host for life by establishing latency in neurons. To gain access to these cells, herpes simplex viruses (HSVs) must replicate and block immediate host antiviral responses elicited by epithelial cells and innate immune components early after infection. During these processes, infected and noninfected neighboring cells, as well as tissue-resident and patrolling immune cells, will sense viral components and cell-associated danger signals and secrete soluble mediators. While type-I interferons aim at limiting virus spread, cytokines and chemokines will modulate resident and incoming immune cells. In this paper, we discuss recent findings relative to the early steps taking place during HSV infection and replication. Further, we discuss how HSVs evade detection by host cells and the molecular mechanisms evolved by these viruses to circumvent early antiviral mechanisms, ultimately leading to neuron infection and the establishment of latency.

[Immune evasion by herpes simplex viruses]. / Evasión de la respuesta inmune por virus herpes simplex.

Herpes simplex viruses and humans have co-existed for tens of thousands of years. This long relationship has translated into the evolution and selection of viral determinants to evade the host immune response and reciprocally the evolution and selection of host immune components for limiting virus infection and damage. Currently there are no vaccines available to avoid infection with these viruses or therapies to cure them. Herpes simplex viruses are neurotropic and reside latently in neurons at the trigeminal and dorsal root ganglia, occasionally reactivating. Most viral recurrences are subclinical and thus, unnoticed. Here, we discuss the initial steps of infection by herpes simplex viruses and the molecular mechanisms they have developed to evade innate and adaptive immunity. A better understanding of the molecular mechanisms evolved by these viruses to evade host immunity should help us envision novel vaccine strategies and therapies that limit infection and dissemination.

Evasión de la respuesta inmune por virus herpes simplex / Immune evasion by herpes simplex viruses

Herpes simplex viruses and humans have co-existed for tens of thousands of years. This long relationship has translated into the evolution and selection of viral determinants to evade the host immune response and reciprocally the evolution and selection of host immune components for limiting virus infection and damage. Currently there are no vaccines available to avoid infection with these viruses or therapies to cure them. Herpes simplex viruses are neurotropic and reside latently in neurons at the trigeminal and dorsal root ganglia, occasionally reactivating. Most viral recurrences are subclinical and thus, unnoticed. Here, we discuss the initial steps of infection by herpes simplex viruses and the molecular mechanisms they have developed to evade innate and adaptive immunity. A better understanding of the molecular mechanisms evolved by these viruses to evade host immunity should help us envision novel vaccine strategies and therapies that limit infection and dissemination.

Los virus herpes simplex y humanos co-existen desde decenas de miles de años. Esta prolongada relación se ha traducido en la evolución y selección de determinantes virales para evadir la respuesta inmune y recíprocamente la evolución y selección de componentes inmunes del hospedero para limitar la infección viral y el daño que producen. Actualmente no existen vacunas para evitar la infección de estos virus o terapias que la curen. Los virus herpes simplex son neurotrópicos y permanecen latentes en neuronas de ganglios trigémino y dorsales, reactivándose esporádicamente. La mayoría de las recurrencias por virus herpes simplex son sub-clínicas y por tanto pasan inadvertidas. Aquí discutimos los pasos iniciales de la infección porvirus herpes simplex y los mecanismos moleculares que estos virus han desarrollado para evadir la respuesta inmune innata y adaptativa. Una mejor comprensión de los mecanismos moleculares evolucionados por estos virus para evadir la respuesta inmune del hospedero deberían ayudarnos visualizar nuevas estrategias para desarrollar vacunas y terapias que limiten su infección y diseminación.