The organs were minced with scissors, homogenized, and 10-fold serial dilutions added to Vero cells to determine virus titers by plaque assay [9]. 2.6. conclude that both vaccines are efficacious at preventing neonatal herpes, which leaves the mRNA vaccine as our preferred candidate based on better protection against genital herpes. 1.?Introduction Neonatal ASP3026 herpes is an uncommon but potentially devastating infection [1]. The annual global incidence of neonatal herpes is approximately 14,000 cases, or 1 case per 10,000 births of which HSV-1 comprises 4000 and HSV-2 10,000 [1]. HSV-1 contributes more cases than HSV-2 in the Americas, Europe and Western Pacific [1]. Transmission to newborns most often occurs during labor ASP3026 and delivery from mothers with active genital herpes. Over half the infants with neonatal herpes have disseminated infection or encephalitis, with 60% mortality if untreated, and severe neurologic disease in two-thirds of survivors despite antiviral treatment [1], [2]. Currently, no vaccine is available to prevent genital or neonatal herpes. Efforts to prevent neonatal herpes include visual inspection ASP3026 for lesions at delivery, cesarean section when lesions are present, and behavioral messaging to reduce risk of transmission late in pregnancy. These measures are often ineffective because of asymptomatic infection. An effective method of protection is through maternal antibodies that develop after infection and pass transplacentally or through breast milk to newborns [3], [4]. Vaccination of women is another approach to develop antibodies that can protect newborns until Rabbit Polyclonal to ELF1 they are old enough to be vaccinated on their own, with influenza as an example [5]. An important issue for candidate herpes vaccines is whether maternal antibodies produced by immunization will provide sufficient protection to a newborn that is exposed to HSV either because of breakthrough infection in the pregnant woman or because of postnatal exposure. Murine models of neonatal herpes infection have addressed vaccine protection of newborn pups. Maternal immunization of female mice with an HSV-2 replicant defective live virus vaccine, dl5-29, protected newborn pups against neonatal HSV-1 and HSV-2 infection [6]. A follow up study was performed by these same investigators in a collaboration with our laboratory using an HSV-2 subunit protein vaccine consisting of glycoproteins C, D and E (gC2, gD2, gE2) administered with CpG and alum as adjuvants. Our rationale for using the three immunogens in the trivalent vaccine is that antibodies to gC2 and gD2 neutralize virus, antibodies to gD2 and gE2 block cell-to-cell spread, and antibodies to gC2 and gE2 block immune evasion from antibody and complement [7], [8], [9], [10]. The trivalent protein vaccine also provided excellent protection against HSV-1 and HSV-2 neonatal herpes [11]. We recently reported that immunization of female mice and guinea pigs with gC2, gD2, and gE2 administered as nucleoside-modified mRNA encapsulated in lipid nanoparticles (LNP) outperformed the protein formulation in preventing genital herpes infection [7]. ASP3026 Immunization with nucleoside-modified mRNA-LNP has gained considerable recognition in response to COVID-19, and is a highly promising approach for infectious disease vaccine ASP3026 development [12], [13], [14]. The nucleoside-modified mRNA immunogens have been particularly potent in producing high titer antibody responses, likely related to potent CD4+ T follicular helper cell and germinal center B cell responses [15]. Three years ago, we began transitioning from a trivalent baculovirus protein vaccine to a nucleoside-modified mRNA vaccine for prevention of genital herpes [7], [8]. Here, we compared protection provided by immunization of mothers (dams) with the baculovirus protein vaccine or the nucleoside-modified mRNA vaccine against intranasal (IN) HSV-2 infection in pups. 2.?Materials and methods 2.1. Mice Protocol 805187 was approved by the University of Pennsylvania Institutional Animal Care and Use Committee following guidelines of National Institutes of Healths Guide for the Care and Use of Laboratory Animals. 2.2. Vaccines Female 6C8-week-old BALB/c mice (Charles River) were immunized intramuscularly (IM) prior to mating using trivalent mRNA-LNP, trivalent protein CpG/alum, or Poly(C) RNA-LNP (control) as immunogens [7]. The control immunogen contained 10?g of Poly(C) RNA, while the nucleoside-modified mRNA vaccine contained 10?g each of gC2, gD2 and gE2 at a ratio of 1 1? g RNA or mRNA to 20?g LNP. The protein vaccine contained 5?g each of gC2, gD2 and gE2 with 50?g CpG/mouse and 25?g alum/g protein. Two immunizations one month apart were performed with mRNA or Poly(C), while three immunizations two weeks apart were administered with the protein vaccine, each in a volume of 50?l. 2.3. Breeding and infection (see graphic abstract) Immunizations with mRNA or Poly(C) were on days ?70 and ?42, or with.