一种快速、简便检测鸭乙型肝炎病毒抗原、抗体的方法

本文报道检测鸭乙型肝炎表面抗原(DHBsAg)及抗体的斑点酶免疫测定法(Dot Euzyme Immunoassay,Dot EIA)。以硝基纤维素膜为载体依次加被检血清、抗DHBV免疫血清、辣根过氧化物酶标记葡萄球菌A蛋白(SPA-酶结合物),可测标本中DHBsAg。依次加纯化DHBV、被检血清、SPA-酶结合物则可测血清中抗体及效价。用此法检测自然感染鸭血清40份,实验感染鸭血清220份,并与DHBV核酸斑点杂交法比较分析,两种方法符合率94.2％。用本方法测定本室制备的兔抗DHBV免疫血清,抗体效阶为1/3200。Dot EIA简单、快速、敏感、特异,是研究DHBV较有实用价值的一种方法。     

Economic impacts of avian influenza outbreaks in Kerala,India

This study assessed the short‐run impact to poultry farmers, duck hatcheries, control costs, compensation paid to stakeholders (transfer payments) and market reactions on own and substitute product prices and backwater tourism (boat operators) due to avian influenza (AI ) outbreaks in Kuttanad region of Kerala, India, during 2014. The primary data from 91 poultry farms (duck farms, broiler chicken and backyard poultry), four hatcheries and 90 backwater boat owners were collected through pre‐tested schedules. The secondary data on transfer payments and expenditure incurred to control AI were collected from developmental departments and were analysed. The estimated loss (culling live birds, eggs and feed destruction) per duck farm was USD 9,181, USD 3,889 and USD 156 in case of commercial farms reared for meat, dual‐purpose and backyard farms, respectively. The loss incurred by small‐scale broiler and backyard poultry farms was USD 453 and USD 40, respectively. The loss incurred by large and small duck hatcheries was USD 11,963 and USD 5,790, respectively, due to culling of hatchlings, young birds and destroying eggs. The government invested USD 744,890 to contain the disease spread through massive culling, surveillance and monitoring of poultry and humans due to zoonotic nature of the disease. A sharp market reaction on own and substitute product prices and eight weeks’ time lag in price recovery was observed. The consequential impact on tourism especially for the backwater boat operators amounted to a loss of USD 2,280/boat due to fall in tourist inflow. Since, control measures are post‐incidence, it is necessary to adopt appropriate preventive bio‐security measures at the farm level besides periodical screening of domestic birds in migratory birds’ flyway locations like Kuttanad to reduce the AI burden on various stakeholders including government.     

Daily variation in the concentration of 5-methoxytryptophol and melatonin in the duck pineal gland and plasma

The duck pineal gland rhythmically produces two 5-methoxyindole compounds, i.e. 5-methoxytryptophol and melatonin. 5-Methoxytryptophol levels are low at night and high during the day, while melatonin concentrations are high at night and low during the day. The melatonin rhythm reflects oscillations in the activity of serotonin N-acetyltransferase (AA-NAT; a penultimate and key regulatory enzyme in the melatonin biosynthetic pathway). The activity of hydroxyindole-O-methyltransferase (HIOMT; an enzyme involved in the synthesis of both 5-methoxytryptophol and melatonin) does not exhibit any significant rhythmic changes throughout the 24-hr period. Plasma levels of melatonin exhibited daily changes that were parallel to fluctuations in pineal melatonin content. Although plasma concentrations of 5-methoxytryptophol were low in ducks, they showed daily variations. The mean 5-methoxytryptophol concentration between zeitgeber time 9 (ZT9) and ZT15 was 2.4-times higher than the mean value for samples collected between ZT18 and ZT3. These findings indicate that in the duck the pineal production of 5-methoxytryptophol and melatonin may be inversely correlated.     

Multiple Reassortants of H5N8 Clade 2.3.4.4b Highly Pathogenic Avian Influenza Viruses Detected in South Korea during the Winter of 2020–2021

During October 2020–January 2021, we isolated a total of 67 highly pathogenic avian influenza (HPAI) H5N8 viruses from wild birds and outbreaks in poultry in South Korea. We sequenced the isolates and performed phylogenetic analysis of complete genome sequences to determine the origin, evolution, and spread patterns of these viruses. Phylogenetic analysis of the hemagglutinin (HA) gene showed that all the isolates belong to H5 clade 2.3.4.4 subgroup B (2.3.4.4b) and form two distinct genetic clusters, G1 and G2. The cluster G1 was closely related to the 2.3.4.4b H5N8 HPAI viruses detected in Europe in early 2020, while the cluster G2 had a close genetic relationship with the 2.3.4.4b H5N8 viruses that circulated in Europe in late 2020. A total of seven distinct genotypes were identified, including five novel reassortants carrying internal genes of low pathogenic avian influenza viruses. Our Bayesian discrete trait phylodynamic analysis between host types suggests that the viruses initially disseminated from migratory waterfowl to domestic duck farms in South Korea. Subsequently, domestic duck farms most likely contributed to the transmission of HPAI viruses to chicken and minor poultry farms, highlighting the need for enhanced, high levels of biosecurity measures at domestic duck farms to effectively prevent the introduction and spread of HPAI.     

满天星积雪草苷抗鸭乙肝病毒作用

目的 研究满天星积雪草苷抗鸭乙肝病毒的作用.方法 将鸭乙型肝炎病毒DNA(DHBV-DNA)阳性麻鸭随机分为5组:模型组,阳性对照组(拉米夫定,3TC),满天星积雪草苷高、中、低剂量组,每组10只,各组麻鸭灌胃给药14 d,于用药前、用药7、14 d及停药后3d采血,检测血清鸭乙肝病毒表面抗原/e抗原(DHBsAg/DHBeAg)、DHBV-DNA和谷丙转氨酶/谷草转氨酶(ALT/AST)给药前后的变化,并观察肝组织病理改变.结果 与模型组比较,满天星积雪草皂苷高、中剂量组,阳性对照组用药后血清中DHBV-DNA、HBsAg、HBeAg、ALT、AST水平均明显降低(均P＜0.05);停药后3d,满天星积雪草皂苷高剂量组的DHBV DNA、HBsAg、HBeAg、ALT、AST水平为(1.21 ±0.11)、(0.12±0.01)、(0.11 ±0.01)、(122.4 ±15.5)、(85.2±9.4),模型组为(3.05±0.15)、(0.22±0.01)、(0.17 ±0.02)、(270.4 ±16.4)、(141.9±9.8),均低于模型组(均P＜0.05),阳性对照组为(2.36±0.13)、(0.18±0.01)、(0.15 ±0.01)、(233.5±13.8)、(121.3 ±10.2),出现明显反跳现象;病理分析表明,满天星积雪草苷对肝损伤有明显改善作用.结论 积雪草苷能有效抑制HBV在体内复制,可能是满天星中一个主要的生物活性成分.     

参灵益肝颗粒抗乙型肝炎病毒作用的实验研究

目的研究参灵益肝颗粒体内抗乙型肝炎病毒的作用。方法采用重庆麻鸭乙型肝炎动物模型,随机分为参灵益肝颗粒（简称参灵益肝）1．6g／kg、3．2g／kg、6．4g／kg3个剂量组,拉米夫定（阳性药）组及病毒对照组。检测血清中的DHBV—DNA、DHBsAg的变化情况及观察肝脏病理改变情况。结果参灵益肝3个剂量组及阳性药组用药21天后血清中的DHBV—DNA显著降低（P〈0．05或P〈0．01）,停药7天后阳性药组及参灵益肝小、大剂组出现反跳。参灵益肝3个剂量组血清中DHBsAg均无明显降低。镜下观察各组鸭肝脏的病理改变较轻,参灵益肝3个剂量组与阳性药组差异无显著性（P〉0．05）。结论参灵益肝颗粒在鸭体内有一定的抑制鸭乙型肝炎病毒DNA的作用。     

Ontogeny of ghrelin mRNA expression and identification of ghrelin-immunopositive cells in the gastrointestinal tract of the Peking duck, Anas platyrhychos

Ghrelin is an acylated peptide and an endogenous ligand for the growth hormone secretagogue receptor (GHS-R), and stimulates growth hormone release and food intake in mammals. Peking duck is a very fast growing species of poultry. Although the sequence and structure of ghrelin have recently been determined, the expression of ghrelin in Peking duck has not been studied. Here, we investigated the tissue expression and distribution of ghrelin by RT-PCR and immunohistochemistry, respectively, in Peking duck at different stages of development. Ghrelin mRNA expression was mainly detected in the proventriculus and proventriculus-gizzard junction. It was first expressed, but weakly, on embryonic day 14 (E14); the expression increased by embryonic day 21 (E21), and was maintained at high levels between post-hatching-day 1 (P1) and post-hatching-day 60 (P60). Weak expression of ghrelin mRNA was also found in the gizzard and duodenum. In the gastrointestinal tract of growing Peking duck in P60, the largest number of ghrelin-ip cells was detected in the epithelium of the compound tubular glands in the proventriculus and the next largest number was in the proventriculus-gizzard junction. Very few ghrelin-ip cells were located in the epithelium of the simple tubular glands adjacent to the gizzard. No ghrelin-ip cells were observed elsewhere in the gastrointestinal tract. Ghrelin-ip cells were found in embryos as early as day E21; at the same time, the compound tubular glands in the proventriculus had formed. The numbers of ghrelin-ip cells on P1 were similar to those of E21 embryos. However, on P60, high numbers of strongly stained ghrelin-ip cells were found to be scattered in the epithelium of the compound tubular glands in the proventriculus. The density of ghrelin-ip cells (cells/mm²) in the proventriculus on P60 was significantly greater than those of P1 and E21 embryos. These results demonstrate that ghrelin is expressed in the Peking duck gastrointestinal tract, especially in the proventriculus, from mid-late-stage embryos to growing period and suggested an involvement of ghrelin in the development and biology of the gastrointestinal tract of the Peking duck.     

Pathogenicity and antigenicity of a new influenza A (H5N1) virus isolated from duck meat

Avian influenza A viruses are the ancestral origin of all human influenza viruses. The outbreak of highly pathogenic (HP) avian H5N1 in Hong Kong in 1997 highlighted the potential of these viruses to infect and cause severe disease in humans. Since 1999, HP H5N1 viruses were isolated several times from domestic poultry in Asia. In 2001, a HP H5N1 virus, A/Duck/Anyang/AVL-1/2001 (Dk/Anyang), was isolated from imported frozen duck meat in Korea. Because of this novel source of HP H5N1 virus isolation, concerns were raised about the potential for human exposure and infection; we therefore compared the Dk/Anyang virus with HP H5N1 viruses isolated from humans in 1997 in terms of antigenicity and pathogenicity for mammals. At high doses, Dk/Anyang virus caused up to 50% mortality in BALB/c mice, was isolated from the brains and lymphoid organs of mice, and caused lymphopenia. Overall Dk/Anyang virus was substantially less pathogenic for mice than the H5N1 virus isolated from a fatal human case in 1997. Likewise, Dk/Anyang virus was apathogenic for ferrets. Dk/Anyang virus was antigenically distinguishable by hemagglutination-inhibition (HI) assay from human H5N1 viruses isolated in 1997 and avian H5N1 viruses isolated in 2001 in Hong Kong. Nevertheless, prior infection with Dk/Anyang virus protected mice from death after secondary infection with HP human H5N1 viruses. These results indicate that compared with HP human H5N1 viruses, Dk/Anyang virus is substantially less pathogenic for mammalian species. Nevertheless, the novel source of isolation of this avian H5N1 virus must be considered when evaluating the potential risk to public health.