Abstract：
With the emergence of clade 2.3.4.4b H5N1 highly pathogenic avian influenza virus (AIV) infection of dairy cattle and its subsequent detection in raw milk, coupled with recent AIV infections affecting dairy farm workers, experiments were conducted to affirm the safety of cooked ground beef related to AIV because such meat is often derived from cull dairy cows. Specifically, retail ground beef (percent lean:fat = ca. 80:20) was inoculated with a low pathogenic AIV (LPAIV) isolate to an initial level of 5.6 log10 EID50 per 300 g patty. The inoculated meat was pressed into patties (ca. 2.54 cm thick, ca. 300 g each) and then held at 4°C for up to 60 min. In each of two trials, two patties for each of the following three treatments were cooked on a commercial open-flame gas grill to internal instantaneous temperatures of 48.9°C (120°F), 62.8°C (145°F), or 71.1°C (160°F), but without any dwell time. Cooking inoculated ground beef patties to 48.9°C (ave. cooking time of ca. 15 min) resulted in a mean reduction of ≥2.5 ± 0.9 log10 50% egg infectious doses (EID50) per 300 g of ground beef as assessed via quantification of virus in embryonating chicken eggs (ECE). Likewise, cooking patties on a gas grill to 62.8°C (ave. cooking time of ca. 21 min) or to the USDA FSIS recommended minimum internal temperature for ground beef of 71.1°C (ave. cooking time of ca. 24 min) resulted in a reduction to non-detectable levels from initial levels of ≥5.6 log10 EID50 per 300 g. These data establish that levels of infectious AIV are substantially reduced within inoculated ground beef patties (20% fat) using recommended cooking procedures.
摘要：
随着2.3.4.4bH5N1高致病性禽流感病毒（AIV）感染奶牛的进化枝的出现及其随后在原料奶中的检测，加上最近影响奶牛场工人的AIV感染，进行实验以确认与AIV相关的煮熟的碎牛肉的安全性，因为这种肉通常来自剔除奶牛。具体来说,零售碎牛肉（瘦肉百分比：脂肪=约。80：20）接种低致病性AIV（LPAIV）分离株，初始水平为每300g肉饼5.6log10EID50。将接种的肉压成肉饼（约2.54厘米厚，CA.每个300g），然后在4°C下保持60分钟。在两次试验中，以下三种处理的两种肉饼在商业明火燃气烤架上烹饪至内部瞬时温度为48.9°C（120°F），62.8°C(145°F),或71.1°C(160°F)，但没有任何停留时间。将接种的碎牛肉饼烹饪至48.9°C（烹饪时间ca。15分钟）导致每300g碎牛肉平均减少≥2.5±0.9log1050％鸡蛋感染剂量（EID50），这是通过对胚胎鸡蛋（ECE）中的病毒进行定量评估的。同样，在燃气烧烤炉上烹饪馅饼至62.8°C(ave.烹饪时间ca。21分钟）或达到USDAFSIS建议的71.1°C碎牛肉的最低内部温度（平均烹饪时间ca。24分钟）导致从每300g≥5.6log10EID50的初始水平降低到不可检测的水平。这些数据表明，使用推荐的烹饪程序，接种的碎牛肉饼（20％脂肪）中的感染性AIV水平大大降低。
