Chinese painted quails immunized with a single dose (6 μg HA) of inactivated H5N1 (clade 1) influenza vaccine NIBRG-14 and challenged with 100 LD50 of the heterologous A/Swan/Nagybaracska/01/06(H5N1) (clade 2.2) strain were protected, whereas unvaccinated quails died after challenge. No viral antigens or RNA were detected in cloacal swabs from immunized animals. Sera obtained post-immunization gave low titres in serological assays against the vaccine and the challenge viruses. Our results demonstrate the protective efficacy of the NIBRG-14 strain against the challenge virus and the usefulness of these small birds in protection studies of influenza vaccines.

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V aricella-zoster virus (VZV) causes varicella by primary infection and herpes zoster by reactivation of the latent virus in the sensory ganglia of infected individuals. After primary infection, the immune response comprises VZV-specific antibody and T cell-mediated immunity (CMI), which are important for recovery from varicella. T cell responses are necessary to control latent VZV in the sensory ganglia. A lack or a declining level of CMI to VZV has been associated with a higher risk of development of herpes zoster (1).A varicella vaccine consisting of live, attenuated strain OKA (vOKA) has been developed in Japan and licensed for mass vaccination in Japan, South Korea, the United States, and several European countries or recommended for only selected groups of the population in other countries (2, 3). To prevent herpes zoster, a zoster vaccine containing 14 times as many PFU of vOKA than the varicella vaccine was developed and licensed for the vaccination of immunocompetent subjects older than 60 years in the United States in 2006 (4). Varicella and zoster vaccines are administered by the subcutaneous (s.c.) route. However, vaccination of immunocompromised individuals with live VZV vaccines can be problematic and different strategies for safe immunization need to be explored (5).Several clinical studies have indicated that the use of a heatinactivated VZV vaccine is an alternative mode of immunization of immunocompromised individuals. Triple vaccination of bone marrow transplant patients with a heat-inactivated varicella vaccine administered s.c. decreased the severity of herpes zoster (6) and four s.c. doses of a heat-inactivated zoster vaccine proved safe and immunogenic in patients with tumor malignancy, HIV-infected individuals, or hematopoietic stem cell transplant recipients (7). When healthy elderly subjects were immunized s.c. with a single dose of either live or heat-inactivated varicella vaccine, there were no differences in antibody responses or IFN-␥ production by peripheral blood mononuclear cells (8). These data indicated that a heat-inactivated VZV vaccine might be useful in preventing herpes zoster. However, protection against herpes zoster following immunization with either a live or heat-inactivated vaccine is not optimal and a more potent antigenic stimulus is needed to improve the efficacy of the vaccine in high-risk patients (9).The skin is a highly immunogenic organ (10). Noninvasive, needle-free liquid jet injection of liquid or powder into the skin has been used in clinical trials for immunization against viral infections (11-13). The barrier structure and thickness of the stratum corneum, the outermost layer of the skin, are similar in guinea pigs and humans (18.6 and 18.2 m, respectively) (14), and thus, the i.d. route of immunization and the effectiveness of a potential i.d. delivery device for humans can be tested in guinea pigs. Moreover, the parental OKA strain is attenuated in human

Despite intensive efforts in recent decades to develop preventive or therapeutic vaccines against diseases caused by herpes simplex virus (HSV), or varicella-zoster virus (VZV), members of the Alpha herpes virinae subfamily of human herpes viruses,a safe and efficient vaccine has been approved for commercial development only against VZV. The VZV vaccine contains a live attenuated strain, OKA. It consists of amixture of at least 13 subpopulations of viruses, all with deletions, insertions or mutations in the genome; the most common mutations are observed in the open reading frame 62 (ORF62). Experience over more than 30 years in Japan, the USA and other countries where VZV vaccination is provided has demonstrated that the vaccine is safe and the effectiveness of two doses compared to unvaccinated children is 98-99%. When administered in a higher dose to stimulate the declining cell-mediated immunity, the same vaccine has been shown to reduce the incidence and severity of herpes zoster in immunocompetent individuals older than 60 years. Vaccination of immuno-compromised subjects with this VZV vaccine is problematic and various strategies need to be explored. Differences in the pathomechanisms of infection, latency and immune evasion of VZV and HSV, together with host genetic factors, may explain the availability of the successful VZV vaccine and the failures of the past HSV vaccine candidates.

We aimed to estimate the proportion of the population infected with SARS-CoV-2 in the first year of the pandemic. The study population consisted of outpatient adults with mild or no COVID-19 symptoms and was divided into subpopulations with different levels of exposure. Among the subpopulation without known previous COVID-19 contacts, 4143 patients were investigated. Of the subpopulation with known COVID-19 contacts, 594 patients were investigated. IgG- and IgA-seroprevalence and RT-PCR positivity were determined in context with COVID-19 symptoms. Our results suggested no significant age-related differences between participants for IgG positivity but indicated that COVID-19 symptoms occurred most frequently in people aged between 20 and 29 years. Depending on the study population, 23.4–74.0% PCR-positive people (who were symptomless SARS-CoV-2 carriers at the time of the investigation) were identified. It was also observed that 72.7% of the patients remained seronegative for 30 days or more after their first PCR-positive results. This study hoped to contribute to the scientific understanding of the significance of asymptomatic and mild infections in the long persistence of the pandemic.