Camel milk is becoming increasingly popular among consumers due to its nutritional and medicinal benefits. However, challenges such as the harsh living conditions required for camels and the relatively low production when compared to cow milk affect the sales of camel milk. Nevertheless, fermented camel milk is an excellent carrier of probiotics, which not only maintain its positive characteristics but also provide additional benefits. In this study, we compared the pH, viable counts, insulin-like growth factor 1 (IGF-1) activity, and microrheological properties of untreated fermented camel milk (control group) and fermented camel milk treated with probiotics (Zhang group [Lacticaseibacillus casei Zhang], V9 group [Bifidobacterium lactis V9], and Mix group [Zhang + V9]). After the addition of probiotics, the fermentation time reduced, potentially decreasing the costs associated with large-scale camel milk fermentation. Finally, eight key metabolites were identified in camel milk and fermented camel milk, we observed that the post-fermentation levels of guanine were significantly higher in the probiotic groups, with the highest levels observed in the Mix group. The research provides a theoretical basis for preparation of probiotic fermented camel milk, and produces a product which can be used to for diabetes patients in the future.

Neutralizing antibodies (NtAbs) against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are indicators of vaccine efficacy that enable immunity surveillance. However, the rapid mutation of SARS-CoV-2 variants prevents the timely establishment of standards required for effective XBB vaccine evaluation. Therefore, we prepared four candidate standards (No. 11, No. 44, No. 22, and No. 33) using plasma, purified immunoglobulin, and a broad-spectrum neutralizing monoclonal antibody. Collaborative calibration was conducted across nine Chinese laboratories using neutralization methods against 11 strains containing the XBB and BA.2.86 sublineages. This study demonstrated the reduced neutralization potency of the first International Standard antibodies to SARS-CoV-2 variants of concern against XBB variants. No. 44 displayed broad-spectrum neutralizing activity against XBB sublineages, effectively reduced interlaboratory variability for nearly all XBB variants, and effectively minimized the geometric mean titer (GMT) difference between the live and pseudotyped virus. No. 22 showed a broader spectrum and higher neutralizing activity against all strains but failed to reduce interlaboratory variability. Thus, No. 44 was approved as a National Standard for NtAbs against XBB variants, providing a unified NtAb measurement standard for XBB variants for the first time. Moreover, No. 22 was approved as a national reference reagent for NtAbs against SARS-CoV-2, offering a broad-spectrum activity reference for current and potentially emerging variants.