戊型肝炎病毒核酸阳性血浆经输血传播感染恒河猴的研究

目的了解戊型肝炎病毒(HEV)核酸阳性血浆对灵长类动物的感染性和致病性。方法对抗-HEV IgM阳性而IgG阴性志愿献血员血浆进行HEV RNA检测，并将存在病毒血症献血员的10ml血浆静脉输入健康恒河猴，观察其对恒河猴的感染性和致病性。结果从1份抗-HEV IgM阳性而IgG阴性志愿献血员血浆中分离出HEV基因IV型RNA片段。该份血浆输入恒河猴后，恒河猴出现典型急性肝炎生物化学和病理表现，病毒血症，血清抗-HEV IgM和IgG抗体阳转。结论HEV病毒血癌献血员血浆输入可以引起灵长类动物的HEV感染以及急性肝炎，提示HEV经输血传播的可能性。     

消灭血吸虫病地区发生急性血吸虫病1例

本文报道了1例消灭血吸虫病地区儿童急性血吸虫病病例,提示此类地区不能放松监测和防治,严防血吸虫病再度发生和流行。     

Prevalence and risk factors for intrafamilial transmission of hepatitis C virus in Karachi,Pakistan

Household contacts of hepatitis C virus (HCV)-positive patients are considered at increased risk of HCV infection. This cross-sectional study during April through June 1999 assessed the prevalence and risk behaviours associated with HCV seropositivity among the household contacts of HCV seropositive thalassaemic children in Karachi, Pakistan. Among the 341 household contacts of 86 thalassaemic HCV seropositive children who were tested, 70 (20.5%) were positive for anti-HCV antibodies. The stratified analysis showed that HCV seroprevalence among the contacts did not differ significantly by the gender of the index patient and the type of relationship of contact with the index patient. However, HCV seroprevalences among the fathers and mothers of male index patients was substantially higher compared to those of female index patients. HCV RNA was recovered and genotyped from nine index patients and corresponding nine HCV-seropositive household contacts. HCV genotype 3a and 3b were found in 89% (8/9) and 11% (1/9) of the pairs, respectively. The final multivariable conditional logistic regression model revealed that after adjusting for the effect of ethnicity and past hospital admission history, the HCV-seropositive household contacts were more likely than HCV seronegative household contacts to have been bitten by the carrier [adjusted matched odds ratio (mOR)=2.6, 95% CI 1.3–5.2] or have shared a toothbrush with the carrier (adjusted mOR=8.2; 95% CI 1.56–43.5). Control efforts should focus on the risk behaviours.     

广西上林县家犬传播华支睾吸虫病潜能调查

目的调查家犬传播华支睾吸虫病的潜在能量,为疾病防控提供依据。方法选择上林县朝文村为调查点,调查全村家犬只数;一次性寻找、捡拾所见全部新鲜犬粪,用醛醚法查华支睾吸虫虫卵,以改良加藤厚涂片(Kato-katz)法作克粪虫卵(EPG)计数,计算日均排卵量。结果全村有家犬66只,一次性检获新鲜犬粪41份。犬粪华支睾吸虫卵检出率为53.66%(22/41),EPG平均为322。推算该村家犬日均排出华支睾吸虫虫卵73.4万个。结论家犬在华支睾吸虫病的传播中具有不可小视的潜在能量,在疾病防控中应给予足够重视。     

Do antibody responses to malaria vaccine candidates influenced by the level of malaria transmission protect from malaria?

Objectives To examine whether the humoural response to malaria vaccine candidate antigens, Plasmodium falciparum [circumsporozoite repetitive sequence (NANP)₅ GLURP fragments (R0 and R2) and MSP3] varies with the level of malaria transmission and to determine whether the antibodies (IgG) present at the beginning of the malaria transmission season protect against clinical malaria. Methods Cross‐sectional surveys were conducted to measure antibody response before, at the peak and at the end of the transmission season in children aged 6 months to 10 years in two villages with different levels of malaria transmission. A cohort study was performed to estimate the incidence of clinical malaria. Results Antibodies to these antigens showed different seasonal patterns. IgG concentrations to any of the four antigens were higher in the village with high entomological inoculation rate. Multivariate analysis of combined data from the two villages indicated that children who were classified as responders to the selected antigens were at lower risk of clinical malaria than children classified as non‐responders [(NANP)₅ (incidence rate ratio (IRR) = 0.65, 95% CI: 0.46–0.92; P = 0.016), R0 (IRR = 0.69, 95% CI: 0.48–0.97; P = 0.032), R2 (IRR = 0.73, 95% CI: 0.50–1.06; P = 0.09), MSP3 (IRR = 0.52, 95% CI: 0.32–0.85; P = 0.009)]. Fitting a model with all four antibody responses showed that MSP3 looked the best malaria vaccine candidate (IRR = 0.63; 95% CI: 0.38–1.05; P = 0.08). Conclusion Antibody levels to the four antigens are affected by the intensity of malaria transmission and associated with protection against clinical malaria. It is worthwhile investing in the development of these antigens as potential malaria vaccine candidates.     

Host’s guardian protein counters degenerative symbiont evolution

Microbial symbioses significantly contribute to diverse organisms, where long-lasting associations tend to result in symbiont genome erosion, uncultivability, extinction, and replacement. How such inherently deteriorating symbiosis can be harnessed to stable partnership is of general evolutionary interest. Here, we report the discovery of a host protein essential for sustaining symbiosis. Plataspid stinkbugs obligatorily host an uncultivable and genome-reduced gut symbiont, Ishikawaella. Upon oviposition, females deposit “capsules” for symbiont delivery to offspring. Within the capsules, the fragile symbiotic bacteria survive the harsh conditions outside the host until acquired by newborn nymphs to establish vertical transmission. We identified a single protein dominating the capsule content, which is massively secreted by female-specific intestinal organs, embedding the symbiont cells, and packaged into the capsules. Knockdown of the protein resulted in symbiont degeneration, arrested capsule production, symbiont transmission failure, and retarded nymphal growth, unveiling its essential function for ensuring symbiont survival and vertical transmission. The protein originated from a lineage of odorant-binding protein-like multigene family, shedding light on the origin of evolutionary novelty regarding symbiosis. Experimental suppression of capsule production extended the female’s lifespan, uncovering a substantial cost for maintaining symbiosis. In addition to the host’s guardian protein, the symbiont’s molecular chaperone, GroEL, was overproduced in the capsules, highlighting that the symbiont’s eroding functionality is compensated for by stabilizer molecules of host and symbiont origins. Our finding provides insight into how intimate host–symbiont associations can be maintained over evolutionary time despite the symbiont’s potential vulnerability to degeneration and malfunctioning.

Microbial symbioses are ubiquitously found in nature, intricately interwoven into the adaptation, ecology, and evolution of almost all life forms (1, 2). In diverse animals encompassing invertebrates and vertebrates, specific microorganisms are present on their body surface, in their alimentary tract, within their body cavity, or even inside their cells (3). In obligate and long-lasting host–symbiont associations, the symbiont genomes often exhibit drastic size reduction and massive gene losses, which are attributed to relaxed natural selection acting on many symbiont genes unnecessary for the intrahost life as well as to irreversibly accumulated deleterious mutations due to strong population bottleneck and restricted horizontal gene acquisitions imposed by continuous vertical transmission (4, 5). Due to the accumulated genetic load, such degenerative symbionts should suffer cellular malfunctioning and instability, which would finally lead to symbiont genome erosion, uncultivability, extinction, and/or replacement (4–7). In this context, both host and symbiont are expected to evolve some molecular mechanisms for stabilizing the symbiotic association that is inherently vulnerable to degeneration and malfunctioning. For the symbiont side, many genome-reduced endosymbiotic bacteria were reported to overproduce molecular capacitors such as heat shock proteins and molecular chaperones, thereby stabilizing molecular structure and functioning of the degenerative bacterial cells (8–10). For the host side, by contrast, little has been known about such molecular mechanisms underpinning the stability of symbiosis. Here, we report the discovery of such a key molecule essential for sustaining symbiosis.     

乙型肝炎母婴阻断现行方案的争议和应重视的问题

母婴传播是HBV传播的重要途径,阻断HBV的母婴传播对乙型肝炎的防治具有重大意义。简述了HBV母婴阻断于分娩前、分娩时、分娩后3个阶段的现行方案,总结了各阶段阻断方案中存在的争议,分析了隐匿性感染和乙型肝炎生殖细胞传染在HBV母婴传播中的重要性。提出乙型肝炎母婴阻断现行方案有待进一步完善和改进,乙型肝炎的隐匿性感染和生殖细胞传染仍需要得到重视。     

Low uptake of HIV testing and no HIV positivity in stable serodiscordant heterosexual partners of long-term treated HIV-infected Thais

The objective of this study was to characterize HIV-serodiscordant heterosexual couples and to evaluate acceptance for HIV testing and HIV prevalence in nonindex partners. We conducted a cross-sectional study with quantitative and qualitative components. Two cohorts of 1767 HIV-positive people were screened to identify heterosexual HIV-serodiscordant couples. HIV-positive partners (index) were administered a questionnaire; CD4, viral load (VL), and antiretroviral therapy (ART) history were gathered from clinical records. HIV-negative/unknown status partners (nonindex) were invited for a similar questionnaire and HIV testing. In-depth interviews with three HIV-serodiscordant couples were conducted. Two hundred and ninety-seven index partners agreed to enroll in this study. The median duration of the relationship was 10 years, and 81% were sexually active. All but two index partners were on ART, and 98% had VL < 1000 copies/mL. Only 111 (37%) nonindex partners came for HIV testing, and all of them tested HIV-negative. In addition, only 41% of nonindex partners had HIV testing in the last one year. The main reasons for the nonindex partners not to come for HIV testing were “no interest” (n = 117, 63%) and “nondisclosure of HIV status” (n = 46, 25%). The latter was substantiated and explained by the qualitative outcome of this study, suggesting relation to stigma against HIV-positive people. Our results support the WHO recommendation for starting ART for treatment and prevention in HIV-serodiscordant couples at any CD4 count. Furthermore, we recommend the dissemination of data showing that no HIV transmission in heterosexual couples through sex practice has been observed provided VL is suppressed. This could be a powerful tool for effective fight against stigma and self-stigma in people living with HIV.     

Experimental infection of pregnant rabbits with hepatitis E virus demonstrating high mortality and vertical transmission

A high mortality rate of approximately 20% in pregnant women with hepatitis E has been reported in previous studies. However, other studies showed no difference between pregnant and nonpregnant women in the severity of hepatitis E. To determine the effects of HEV infection on pregnancy, we successfully established HEV infection in six pregnant rabbits (PR) and six nonpregnant rabbits (NPR) with a rabbit HEV isolate, taking three PR and one NPR without HEV infection as controls. Tests for HEV RNA by RT‐PCR, anti‐HEV antibodies by ELISA and HEV antigen via immunohistochemistry and histopathology were carried out. Two of six infected PR miscarried and three of the remaining four PR died which may be attributed to severe liver necrosis caused by HEV infection. Moreover, vertical transmission was found to be associated with the replication of HEV in placenta, indicated by the presence of HEV RNA and antigen in placenta from the infected PR. Our findings strongly suggest that HEV infection could lead to adverse outcomes in pregnancy and vertical transmission, suggesting the necessity for pregnant women at risk of HEV infection to be vaccinated.