Immunogenic fusion proteins induce neutralizing SARS-CoV-2 antibodies in the serum and milk of sheep.

Antigen-specific polyclonal immunoglobulins derived from the serum, colostrum, or milk of immunized ruminant animals have potential as scalable therapeutics for the control of viral diseases including COVID-19. Here we show that the immunization of sheep with fusions of the SARS-CoV-2 receptor binding domain (RBD) to ovine IgG2a Fc domains promotes significantly higher levels of antigen-specific antibodies compared to native RBD or full-length spike antigens. This antibody population contained elevated levels of neutralizing antibodies that suppressed binding between the RBD and hACE2 receptors in vitro. A second immune-stimulating fusion candidate, Granulocyte-macrophage colony-stimulating factor (GM-CSF), induced high neutralizing responses in select animals but narrowly missed achieving significance. We further demonstrated that the antibodies induced by these fusion antigens were transferred into colostrum/milk and possessed cross-neutralizing activity against diverse SARS-CoV-2 variants. Our findings highlight a new pathway for recombinant antigen design in ruminant animals with applications in immune milk production and animal health.

Milk of Cow and Goat, Immunized by Recombinant Protein Vaccine ZF-UZ-VAC2001(Zifivax), Contains Neutralizing Antibodies Against SARS-CoV-2 and Remains Active After Standard Milk Pasteurization.

Here, we present the first experimental validation of the possibility for obtaining immune milk with neutralizing antibodies against SARS-CoV-2 from vaccinated cows and goat using approved recombinant protein human coronavirus vaccine, ZF-UZ-VAC2001, in the Republic of Uzbekistan. In the period of 2 weeks after first vaccination, we detected the neutralizing antibodies against coronavirus in the blood serum of vaccinated animals. The neutralizing activity, in its peak on the 21st day after receiving the third dose (77th day from first dose), was effective in neutralization test using a live SARS-CoV-2 in Vero E6 cells, even after 120-fold serum titration. In cows receiving three dose of human vaccine, the MAGLUMI® SARS-CoV-2 neutralizing antibody competitive chemiluminescence immunoassay revealed that colostrum of the first day after calving had a greater activity to neutralize the SARS-CoV-2 compared to colostrum of subsequent three days (4.080 µg/ml vs 2.106, 1.960 and 1.126 µg/ml). In comparison, the neutralizing activity for goat and cow milk was 1.486 µg/ml and 0.222 µg/ml, respectively. We observed a positive correlation of receptor-binding domain (RBD)-specific IgG antibodies between the serum of actively immunized cow and milk-feeding calf during the entire course of vaccination (r = 0.95, p = 0.05). We showed an optimal regime for immune milk pasteurization at 62.5°C for 30 min, which retained specific neutralizing activity to SARS-CoV-2, potentially useful for passive immunization against coronavirus infection threats as an additive approach to the vaccination. This strategy, as a supportive approach to the vaccination, could also be applicable for directly reducing the effect of COVID-19 infection in gastrointestinal tract, supporting mucosal immunity.

Bovine Coronavirus Immune Milk Against COVID-19.

After a year of evolution of the SARS-CoV-2 epidemic, there is still no specific effective treatment for the disease. Although the majority of infected people experience mild disease, some patients develop a serious disease, especially when other pathologies concur. For this reason, it would be very convenient to find pharmacological and immunological mechanisms that help control SARS-CoV-2 infection. Since the COVID-19 and BCoV viruses are very close phylogenetically, different studies demonstrate the existence of cross-immunity as they retain shared epitopes in their structure. As a possible control measure against COVID-19, we propose the use of cow's milk immune to BCoV. Thus, the antigenic recognition of some highly conserved structures of viral proteins, particularly M and S2, by anti-BCoV antibodies present in milk would cause a total or partial inactivation of SARS-COV-2 (acting as a particular vaccine) and be addressed more easily by GALT's highly specialized antigen-presenting cells, thus helping the specific immune response.

Can Drinking Microfiltered Raw Immune Milk From Cows Immunized Against SARS-CoV-2 Provide Short-Term Protection Against COVID-19?

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes severe respiratory tract infections in humans (COVID-19), has become a global health concern. Currently, several vaccine candidates against SARS-CoV-2 are in clinical trials but approval of these vaccines is likely to take a long time before they are available for public use. In a previous report, the importance of passive immunity and how immunoglobulin (Ig)G collected from recovered coronavirus patients could help in the protection against COVID-19 and boost the immune system of new patients was reported. Passive immunity by immunoglobulin transfer is a concept employed by most mammals and bovine IgG has a role to play in human therapy. IgG is one of the major components of the immunological activity found in cow's milk and colostrum. Heterologous transfer of passive immunity associated with the consumption of bovine immune milk by humans has been investigated for decades for its immunological activity against infections. This short review focuses on passive immunity and how microfiltered raw immune milk or colostrum collected from cows vaccinated against SARS-CoV-2 could provide short-term protection against SARS-CoV-2 infection in humans and could be used as an option until a vaccine becomes commercially available.