Propagation of hepatitis A virus in human embryo fibroblasts

human diploid fibroblasts and human primary liver cell carcinoma cells (PLC/PRF/5) were infected with hepatitis A virus (HAV) adapted to growth in cell culture or derived directly from human stool. Viral antigen was expressed in PLC/PRF/5 cells 28 days after infection with cell culture-adapted HAV, and 50 days after infection with virus from human stool. In human fibroblasts the periods until first expression of viral antigen were 90 and 210 days, respectively. During further passages of HAV in fibroblasts the time of first appearance of antigen decreased to about 28 days. Biophysical properties of HAV extracted from infected fibroblasts were comparable to those of HAV derived directly from human stool. Immunofluorescence studies showed that the antigen was located exclusively within the cytoplasm of the infected fibroblasts. Kinetics of antigen production indicated that an equilibrium between virus multiplication and cell metabolism was reached in persistently infected fibroblasts.     

部队甲型病毒性肝炎疫苗的接种策略

目的 探讨部队甲肝疫苗接种的最佳策略。方法 应用决策树模型和成本效用分析方法。结果 部队官兵接种甲肝疫苗,先筛选后接种方案优于直接接种方案;采用先筛选后接种方案接种干部每增加一个DALY将产生168.23元的正效益,而新兵则需2792.30元的净投入。经灵敏度分析,该决策结果稳定,不随引入决策模型的各参数的变化而变化。结论 在当前条件下,部队接种甲肝疫苗宜首选先筛选后接种方案,优先接种干部人群。     

地高辛标记RT-PCR检测甲肝减毒活疫苗的研究

以编码甲肝病毒ＶＰ３ 羧基端的基因区为目标区,运用地高辛标记ＲＴＰＣＲ 法对甲肝疫苗进行检测,并与ＴＣＩＤ５０ 检测法进行比较。建立甲肝减毒活疫苗滴度的地高辛标记ＲＴＰＣＲ 检测法。结果显示：地高辛ＲＴＰＣＲ 法灵敏度略高于ＴＣＩＤ５０ 法,特异性与ＴＣＩＤ５０ 相似,且快速简便,易于推广应用。结果表明：地高辛标记ＲＴＰＣＲ 法是一种简便、快速、灵敏的甲肝病毒检测方法,可用作疫苗的常规检测。     

甲型肝炎减毒活疫苗免疫程序的探讨

５２名ＨＡＶ抗体阴性的儿童,按０、３个月免疫程序,经２针低剂量（５．５０ｌｇＣＣＩＤ５０／ｍｌ）甲型肝炎减毒活疫苗免疫,于第２针接种后７天检测ＨＡＶ抗体阳转率为１００％,抗体效价ＧＭＴ值为１∶１４;全部接种儿童的ＡＬＴ均在正常范围内（２～２４μｌ）;免前ＨＡＶ抗体阳性的儿童,经２针免疫后,抗体效价增长在２倍以上     

Impact of Hepatitis A vaccination with a two-dose schedule in Panama: Results of epidemiological surveillance and time trend analysis

PurposeIn April 2007, Panama introduced Hepatitis A universal vaccination using a two-dose schedule (Havrix^® junior; GSK Vaccines, Belgium). We assessed the impact of this hepatitis A vaccine three years after it was recommended for universal mass vaccination in Panama.Materials and methodsHepatitis A vaccination impact was assessed using two different approaches. The first approach used retrospective data (incidence and number of cases for all age groups), collected from the passive surveillance of the Epidemiologic Surveillance System of the Ministry of Health of hepatitis A and unspecified hepatitis before (2000–2006) and after (2008–2010) introduction of hepatitis A vaccine. The second approach was a prospective hospital-based active surveillance for hepatitis cases conducted in subjects (0–14years) during 2009–2011 at three sentinel hospitals in Panama.ResultsOverall, the annual incidence of hepatitis A and unspecified hepatitis in 2008, 2009 and 2010 were 13.1, 7.9 and 3.7 per 100,000 subjects, lower than the baseline incidence of 51.1 per 100,000 subjects. In comparison to the mean baseline period (2000–2006), there was an 82% mean reduction in the overall hepatitis-related outcomes (hepatitis A and unspecified hepatitis) after vaccine introduction (2008–2010) in all age groups.In the hospital-based surveillance (2009–2011), of the 42 probable viral hepatitis A cases, nine cases were confirmed as acute hepatitis A (8 in 2009, 1 in 2010). Of these confirmed cases, two belonged to the targeted vaccine group (1–4 years) but were not vaccinated.ConclusionsOur study suggests that the introduction of two-dose hepatitis A vaccines in Panama has contributed to the reduction in the incidence of overall hepatitis-related outcomes for all age groups, suggesting herd protection. Additional monitoring is required to document a sustained long-term effect.     

Identification of hepatitis A virus mimotopes by phage display, antigenicity and immunogenicity

A phage-displayed peptide approach was used to identify ligands mimicking antigenic determinants of hepatitis A virus (HAV) for the first time. Bacteriophages displaying HAV mimotopes were isolated from a phage-display peptide library by affinity selection on serum antibodies from hepatitis A patients. Selected phage-peptides were screened for reactivity with sera from HAV infected patients and healthy controls. Four cloned peptides with different sequences were identified as mimotopes of HAV; three of them showed similarity in their amino acid sequences with at least one of the VP3 and VP1 antigenic proteins of HAV. One clone was recognised by 92% of the positive sera. The phagotopes competed effectively with HAV for absorption of anti-HAV-specific antibodies in human sera, as determined by ELISA. The four phage clones induced neutralising anti-HAV antibodies in immunised mice. These results demonstrate the potential of this method to elucidate the disease related epitopes of HAV and to use these mimotopes in diagnostic applications or in the development of a mimotope-based hepatitis A vaccine without the necessity of manipulation of the virus.     

Recent trends in hepatitis A incidence in Brazil

Hepatitis A incidence has been decreasing in Brazil since child vaccination was implemented in 2014. This trend was interrupted by an outbreak among adult male in São Paulo in 2017. This study was outlined to estimate whether the increase of hepatitis A cases among adult men in Brazil was restricted to São Paulo. Cases reported to the national surveillance system from 14 large cities of all Brazilian regions were analyzed. Trends in time series from 2012 to 2018 were estimated by Prais-Winsten regression. The outbreak in São Paulo extended to 2018. In Rio de Janeiro, the number of cases rose again, achieving the same levels reported before the vaccination era. Three of six cities from South and Southeast regions showed an upward trend in the number of cases among adult men (P < .005). The large cities in the other three Brazilian macroregions showed a decrease or stabilization of cases without an increase among male adults. The increase of hepatitis A virus (HAV) cases in Brazil has happened not only in São Paulo, but also in other cities of South and Southeast regions. The northernmost cities were not affected. A change in the epidemiological pattern of HAV infection is emerging in Southern Brazil.