Chun-Yi Lu

Waning immunity to plasma-derived hepatitis B vaccine and the need for boosters 15 years after neonatal vaccination

Neonatal immunization with hepatitis B (HB) vaccine is highly effective; however, more needs to be learned about the duration of protection and indications for boosters. We measured antibody to HB core antigen (anti‐HBc), HB surface antigen (HBsAg), and pre‐ and postbooster titers of HBsAg antibody (anti‐HBs) 15 years after primary neonatal immunization with plasma‐derived HB vaccines in 2 cohorts of 15‐year‐old children. Group A consisted of 78 children who were born to HB e antigen–positive HBsAg carrier mothers and had developed protective levels of anti‐HBs antibodies (≥10 mIU/mL) following HB immunization. Group B consisted of 113 apparently healthy children whose anti‐HBs titers after vaccination were unknown. Anti‐HBs was undetectable (antibody titer <10 mIU/mL) in 29.9% in group A and 62.4% in group B (P < .001). Anti‐HBc was detected in 33.3 % in group A and 4.4 % in group B (P < .001). After a single booster dose of HB vaccine, 2.7% in group A and 3.3% in group B remained anti‐HBs–negative. A blunted serological response was noted in approximately 20% in both groups. One HBsAg carrier was detected in group A (1.3%) and 4 in group B (3.5%). Fifteen years after neonatal immunization with plasma‐derived HB vaccine, a large proportion of children exhibited waning immunity. This poses the risk of breakthrough infection. A single booster augmented the serological response to the vaccine in most but not all subjects. In conclusion, our findings suggest that one or more booster immunizations are needed in seronegative subjects by at least 15 years following neonatal immunization with plasma‐derived HB vaccine. (HEPATOLOGY 2004;40:1415–1420.)

Humoral and Cellular Immune Responses to a Hepatitis B Vaccine Booster 15–18 Years after Neonatal Immunization

BACKGROUND Whether hepatitis B (HB) vaccine-conferred immunity persists into adulthood is unknown. We aimed to investigate long-term HB immunity in adolescents. METHODS In 2004-2005, 6156 high school students (15-21 years old) who had been vaccinated with plasma-derived HB vaccine as infants were recruited for HB seromarker screening. The immune response to an HB vaccine booster was evaluated in 872 subjects who were seronegative. HB surface antibody (anti-HBs) titers and levels of HB surface antigen (HBsAg)-specific interferon (IFN)-gamma- or interleukin (IL)-5-secreting peripheral blood mononuclear cells (PBMCs; measured by enzyme-linked immunospot assay) were determined 4 weeks later. RESULTS Although the vaccine remained highly efficacious in reducing the HBsAg positivity rate, 63.0% of the vaccinees had no protective anti-HBs. After the booster, anti-HBs remained undetectable in 28.7% (158/551) of the subjects who had received complete HB vaccination (4 doses) during infancy. We estimated that 10.1% of the total population had lost their HB vaccine-conferred booster response. HBsAg-specific IFN-gamma- or IL-5-secreting PBMCs remained negative in 27.2% (25/92) of subjects after the booster. CONCLUSIONS A notable proportion of fully vaccinated adolescents had lost immune memory conferred by a plasma-derived HB vaccine 15-18 years later. This decay of immune memory may raise concerns about the need for a booster vaccine for high-risk groups in the long run.

Influenza Pandemics: Past, Present and Future

Influenza A virus is well known for its capability for genetic changes either through antigen drift or antigen shift. Antigen shift is derived from reassortment of gene segments between viruses, and may result in an antigenically novel virus that is capable of causing a worldwide pandemic. As we trace backwards through the history of influenza pandemics, a repeating pattern can be observed, namely, a limited wave in the first year followed by global spread in the following year. In the 20th century alone, there were three overwhelming pandemics, in 1918, 1957 and 1968, caused by H1N1 (Spanish flu), H2N2 (Asian flu) and H3N2 (Hong Kong flu), respectively. In 1957 and 1968, excess mortality was noted in infants, the elderly and persons with chronic diseases, similar to what occurred during interpandemic periods. In 1918, there was one distinct peak of excess death in young adults aged between 20 and 40 years old; leukopenia and hemorrhage were prominent features. Acute pulmonary edema and hemorrhagic pneumonia contributed to rapidly lethal outcome in young adults. Autopsies disclosed multiple-organ involvement, including pericarditis, myocarditis, hepatitis and splenomegaly. These findings are, in part, consistent with clinical manifestations of human infection with avian influenza A H5N1 virus, in which reactive hemophagocytic syndrome was a characteristic pathologic finding that accounted for pancytopenia, abnormal liver function and multiple organ failure. All the elements of an impending pandemic are in place. Unless effective measures are implemented, we will likely observe a pandemic in the coming seasons. Host immune response plays a crucial role in disease caused by newly emerged influenza virus, such as the 1918 pandemic strain and the recent avian H5N1 strain. Sustained activation of lymphocytes and macrophages after infection results in massive cytokine response, thus leading to severe systemic inflammation. Further investigations into how the virus interacts with the hosts immune system will be helpful in guiding future therapeutic strategies in facing influenza pandemics.

Status of cellular rather than humoral immunity is correlated with clinical outcome of enterovirus 71.

We valuated specific cellular and humoral immune response of cases of enterovirus 71 (EV71) infection and correlated immune response with clinical outcome. After obtaining informed consent, we enrolled 30 EV71 cases including 7 cases with brainstem encephalitis plus pulmonary edema, 12 cases of CNS (CNS) involvement and 11 uncomplicated cases. We measured antibodies specific to EV71, lymphocyte proliferation response and EV71-stimulated cellular response of Th1/Th2 cytokines and chemokines. The 7 EV71 cases involving brainstem encephalitis plus pulmonary edema had a significantly lower phytohemagglutinin stimulation index than other cases (p = 0.04). After EV71 stimulation of peripheral mononuclear cells, there was a significant increase in cellular Th1 cytokine (γ-interferon) and proinflammatroy cytokines. However, cases with pulmonary edema had significantly lower cellular γ-interferon (p = 0.04), lower cellular IL-1β (p = 0.04), lower cellular IL-6 (p = 0.04), lower cellular tumor necrosis factor-α response (p = 0.04), and lower cellular macrophage inflammatory protein-1α (p = 0.04) response compared with other cases. Their titers of EV71 neutralizing antibodies demonstrated no difference among cases. These results suggest lower EV71-specific cellular response may be associated with immunopathogenesis of EV71-related pulmonary edema.

Epidemiologic features of Kawasaki disease in Taiwan, 1996-2002.

Objective. Kawasaki disease (KD) is the most common acquired heart disease in children worldwide. The incidence of KD varies among different countries, with Asian countries supposedly having higher incidences than Western countries. However, the incidence of KD in Taiwan has not been well investigated. Methods. Since the implementation of Taiwans National Health Insurance (NHI) in 1995, NHI has covered health care for >96% its population. Using the NHI database from 1996 to 2002, we investigated epidemiologic features of KD (International Classification of Diseases, Ninth Revision, code 446.1), the rate of coronary artery aneurysm formation (International Classification of Diseases, Ninth Revision, code 414.11), and the change in incidence during the recent 7 years. We also compared the annual incidences in Taiwan with those reported by other countries. Results. During the 7-year study period, KD occurred most frequently in the summer and least frequently in winter. It is interesting that the highest peak occurred in the summer of 1998 at the same time that Taiwans enterovirus 71 epidemic was occurring. Ninety-one percent of KD cases occurred in children who were <5 years old, and the male-to-female ratio was 1.70:1. Recurrence of KD was found in 1.3% (94 of 7305) of these children, and coronary artery aneurysm was found in 7.3% (536 of 7305). The annual incidence per 100 000 children was 146 in children <1 year old, 98 in 1-year-old children, 51 in 2-year-old children, 28 in 3-year-old children, 19 in 4-year-old children, and 5.3 in 5- to 9-year-old children; the incidence of KD decreased with increased age. The overall incidence was 66 cases per 100 000 children <5 years old from 1996 to 2002 with the annual incidence not differing significantly during the 7-year study period. Conclusions. KD in Taiwan occurs more frequently in boys and in the summer months. During the 7-year study period, the annual KD incidence in Taiwan of 66/100000 in children <5 years old was the second highest in the world after Japan.

Human Immunodeficiency Virus Type 1 Vpr Interacts with Antiapoptotic Mitochondrial Protein HAX-1

ABSTRACT Human immunodeficiency virus type 1 viral protein R (Vpr) is required for viral pathogenesis and has been implicated in T-cell apoptosis through its activation of caspase 3 and caspase 9 and perturbation of mitochondrial membrane potential. To understand better Vpr-mitochondria interaction, we report here the identification of antiapoptotic mitochondrial protein HAX-1 as a novel Vpr target. We show that Vpr and HAX-1 physically associate with each other. Overexpression of Vpr in cells dislocates HAX-1 from its normal residence in mitochondria and creates mitochondrion instability and cell death. Conversely, overexpression of HAX-1 suppressed the proapoptotic activity of Vpr.

An in Vivo Replication-important Function in the Second Coding Exon of Tat Is Constrained against Mutation despite Cytotoxic T Lymphocyte Selection

Human and simian immunodeficiency virus (HIV/SIV) Tat proteins are specified by two coding exons. Tat functions in the transcription of primate lentiviruses. A plethora of in vitro data currently suggests that the second coding exon of Tat is largely devoid of function. However, whether the second exon of Tat contributes functionally to viral pathogenesis in vivo remains unknown. To address this question directly, we compared infection of rhesus macaques with an SIV, engineered to express only the first coding exon of Tat (SIVtat1ex), to counterpart infection with wild-type SIVmac239 virus, which expresses the full 2-exon Tat. This comparison showed that the second coding exon of Tat contributes to chronic SIV replication in vivo. Interestingly, in macaques, we observed a cytotoxic T lymphocytes (CTL) response to the second coding exon of Tat, which appears to durably control SIV replication. When SIV mutated in an attempt to escape this second Tat-exon-CTL, the resulting virus was less replicatively fit and failed to populate the host in vivo. Our study provides the first evidence that the second coding exon in Tat embodies an important function for in vivo replication. We suggest the second coding exon of Tat as an example of a functionally constrained “epitope” whose elicited CTL response cannot be escaped by virus mutation without producing a virus that replicates poorly in vivo.

Identification of a novel protein 3a from severe acute respiratory syndrome coronavirus.

The open reading frame 3 of the severe acute respiratory syndrome coronavirus (SARS‐CoV) genome encodes a predicted protein 3a, consisting of 274 amino acids, that lacks any significant similarities to any known protein. We generated specific antibodies against SARS protein 3a by using a synthetic peptide (P2) corresponding to amino acids 261–274 of the putative protein. Anti‐P2 antibodies and the sera from SARS patients could specifically detect the recombinant SARS protein 3a expressed in Escherichia coli and in Vero E6 cells. Expression of SARS protein 3a was detected at 8–12 h after infection and reached a higher level after ∼24 h in SARS‐CoV‐infected Vero E6 cells. Protein 3a was also detected in the alveolar lining pneumocytes and some intra‐alveolar cells of a SARS‐CoV‐infected patients lung specimen. Recombinant protein 3a expressed in Vero E6 cells and protein 3a in the SARS‐CoV‐infected cells was distributed over the cytoplasm in a fine punctate pattern with partly concentrated staining in the Golgi apparatus. Our study demonstrates that SARS‐CoV indeed expresses a novel protein 3a, which is present only in SARS‐CoV and not in other known CoVs.

Disease burden and epidemiology of herpes zoster in pre-vaccine Taiwan

Herpes zoster, a common disease, has an important impact on the health of adults, particularly the elderly, and the health system. This study evaluated the disease burden and epidemiological characteristics of herpes zoster in Taiwan. Using herpes zoster-related ICD-9-CM codes used on Taiwans National Health Insurance claims, we analyzed overall and age group differences in incidence, complications, utilization of healthcare facilities, lengths of stay, and cost of their medical care in Taiwans population from 2000 to 2005. The overall annual incidence of zoster was 4.97 cases per 1000 people, with women having a significantly higher incidence than men (5.20 per 1000 vs. 4.72 per 1000, p<0.001). The incidence increased stepwise with age, with 5.18 cases per 1000 in people 40-50 years old, 8.36 in those 50-60, 11.09 in those 60-70, and 11.77 in those above 70 years old. The estimated lifetime risk of developing herpes zoster was 32.2%. Zoster-related hospitalizations and medical cost per patient increased with age. In conclusion, about two-thirds of Taiwans zoster cases occur in adults older than 40 years old and about one-third of the population would develop zoster within their lifetime.

Hepatitis B virus infection, its sequelae, and prevention by vaccination.

Hepatitis B virus (HBV) infection is a global health problem. There are >350 million of people chronically infected with this virus worldwide. Hepatitis B vaccines are effective in preventing the infection. Humoral immunity is the key factor in conferring the protection. Hepatitis B surface antibody titers of ≥10mIU/mL are protective. Chronic carriage of HBV is related to the age when the infection occurs, the younger the age the higher the chronicity rate. Hence, vaccination should be given in early childhood. People vaccinated in infancy have a protection of >20 years, and hepatocellular carcinoma decreases in them. Although the vaccine-conferred immunity wanes by time, a universal booster is not recommended at present.