Abstract：
In March 2024, clade 2.3.4.4b H5N1 highly pathogenic avian influenza virus (HPAIV) was detected in dairy cattle in the US, and it was discovered that the virus could be detected in raw milk. Although affected cow\'s milk is diverted from human consumption and current pasteurization requirements are expected to reduce or eliminate infectious HPAIV from the milk supply, a study was conducted to characterize whether the virus could be detected by quantitative real-time RT-PCR (qrRT-PCR) in pasteurized retail dairy products and, if detected, to determine whether the virus was viable. From 18 April to 22 April 2024, a total of 297 samples of Grade A pasteurized retail milk products (23 product types) were collected from 17 US states that represented products from 132 processors in 38 states. Viral RNA was detected in 60 samples (20.2%), with qrRT-PCR-based quantity estimates (non-infectious) of up to 5.4log1050% egg infectious doses per mL, with a mean and median of 3.0log10/mL and 2.9log10/mL, respectively. Samples that were positive for type A influenza by qrRT-PCR were confirmed to be clade 2.3.4.4 H5 HPAIV by qrRT-PCR. No infectious virus was detected in any of the qrRT-PCR-positive samples in embryonating chicken eggs. Further studies are needed to monitor the milk supply, but these results provide evidence that the infectious virus did not enter the US pasteurized milk supply before control measures for HPAIV were implemented in dairy cattle.IMPORTANCEHighly pathogenic avian influenza virus (HPAIV) infections in US dairy cattle were first confirmed in March 2024. Because the virus could be detected in raw milk, a study was conducted to determine whether it had entered the retail food supply. Pasteurized dairy products were collected from 17 states in April 2024. Viral RNA was detected in one in five samples, but infectious virus was not detected. This provides a snapshot of HPAIV in milk products early in the event and reinforces that with current safety measures, infectious viruses in milk are unlikely to enter the food supply.
摘要：
2024年3月，在美国的奶牛中检测到2.3.4.4bH5N1高致病性禽流感病毒（HPAIV），人们发现可以在原料奶中检测到病毒。尽管受影响的牛奶被从人类消费中转移，目前的巴氏灭菌要求有望减少或消除牛奶供应中的传染性HPAIV，进行了一项研究，以确定是否可以通过定量实时RT-PCR（qrRT-PCR）在巴氏杀菌的零售乳制品中检测到病毒，如果检测到,以确定病毒是否存活。从2024年4月18日至4月22日，共从美国17个州收集了297份经过巴氏杀菌的零售奶制品（23种产品类型），代表了来自38个州132个加工商的产品。在60个样本中检测到病毒RNA（20.2%），基于qrRT-PCR的数量估计（非感染性）高达5.4log1050％的鸡蛋感染剂量/mL，平均值和中位数为3.0log10/mL和2.9log10/mL，分别。通过qrRT-PCR对A型流感呈阳性的样品通过qrRT-PCR确认为进化枝2.3.4.4H5HPAIV。在胚胎鸡蛋的任何qrRT-PCR阳性样品中均未检测到感染性病毒。需要进一步的研究来监测牛奶供应，但这些结果提供的证据表明,在对奶牛实施HPAIV控制措施之前,感染性病毒并未进入美国巴氏杀菌乳供应.IMPORTANCE2024年3月首次确认了美国奶牛的高致病性禽流感病毒（HPAIV）感染。因为病毒可以在原料奶中检测到，进行了一项研究，以确定它是否已进入零售食品供应。2024年4月从17个州收集了巴氏杀菌乳制品。在五分之一的样本中检测到病毒RNA，但是没有检测到传染性病毒。这提供了事件早期牛奶产品中HPAIV的快照，并通过当前的安全措施加强了这一点，牛奶中的传染性病毒不太可能进入食物供应。
