Veterinary Research Institute, Ipoh, Perak. Malaysia.
Trop Biomed. 2022 Jun 1;39(2):160-169. doi: 10.47665/tb.39.2.001.
Highly Pathogenic Avian Influenza (HPAI) is a highly contagious disease in poultry. The outbreaks can lead to flock mortality up to 100% in two to three days. In July 2018, high mortality in a commercial layer farm in Kauluan village, Sabah was reported. Samples were sent to Veterinary Research Institute Ipoh for diagnosis. Virus isolation and molecular detection is carried out simultaneously. The causative agent was then identified as AI H5N1 virus by real time reverse transcription-polymerase chain reaction (RT-PCR). The virus was then subjected for further nucleotide sequencing of full length hemagglutinin (HA) and neuraminidase (NA) gene. The PQRERRRKR/GLF motif at the HA cleavage site indicated that the isolate was of HPAI virus. Phylogenetic analysis of the HA gene showed that the isolate was belonged to the clade 2.3.2.1c virus. In the HA gene, besides the S133A substitution, the virus possesses conserved amino acid at most of the avian receptor binding sites including the glutamine (Q) and glycine (G) at position 222 and 224 respectively, indicating that the virus retains the avian-type receptor binding preference. As such, the zoonotic potential of the virus was relatively low. On the other hand, though the N154D and T156A substitution were detected in the same gene, the pandemic potential of this Sabah 2.3.2.1c virus is low in the absence of the Q222L, G224S, H103Y, N220K and T315I. A typical 20 amino acid deletion with loss of four corresponding glycosylation sites in the NA stalk region was visible. Though three NA resistance markers were detected, the virus was predicted to be sensitive to NA inhibitor. This is the first HPAI H5N1 outbreak in Sabah. The introduction of this virus into East Malaysia for the first time raised an alert alarm of the future epidemic potential. Strict farm biosecurity, continuous surveillance programme in poultry, wild birds, migratory birds; molecular epidemiology as well as risk assessment for the virus with pandemic potential are needed in dealing with emergence of new influenza virus in the country.
高致病性禽流感（HPAI）是一种在禽类中具有高度传染性的疾病。疫情爆发可导致禽类在两到三天内死亡率高达 100%。2018 年 7 月，沙巴州考鲁兰村的一个商业蛋鸡场报告了高死亡率。样本被送往怡保兽医研究所进行诊断。同时进行病毒分离和分子检测。随后通过实时逆转录聚合酶链反应（RT-PCR）鉴定病原体为 H5N1 病毒。然后对全长血凝素（HA）和神经氨酸酶（NA）基因进行进一步的核苷酸测序。HA 裂解位点的 PQRERRRKR/GLF 基序表明分离株为高致病性禽流感病毒。HA 基因的系统进化分析表明，分离株属于 2.3.2.1c 病毒群。在 HA 基因中，除了 S133A 取代外，病毒在大多数禽受体结合位点都具有保守的氨基酸，包括位置 222 和 224 的谷氨酰胺（Q）和甘氨酸（G），表明病毒保留了禽型受体结合偏好。因此，病毒的人畜共患病潜力相对较低。另一方面，尽管在同一基因中检测到 N154D 和 T156A 取代，但在没有 Q222L、G224S、H103Y、N220K 和 T315I 的情况下，这种沙巴 2.3.2.1c 病毒的大流行潜力较低。在 NA 茎区可见典型的 20 个氨基酸缺失，丧失了四个相应的糖基化位点。尽管检测到三个 NA 耐药标记，但该病毒被预测对 NA 抑制剂敏感。这是沙巴州首次发生 HPAI H5N1 疫情。该病毒首次传入东马来西亚，对未来的流行潜力发出了警报。严格的农场生物安全、对家禽、野生鸟类、候鸟的持续监测计划、分子流行病学以及对具有大流行潜力的病毒进行风险评估，都是应对该国新流感病毒出现所必需的。
