The use of immunomodulators in vaccination of cattle

The effect of two immunocorrectors with a wide spectrum of action Imactin and Polyoxidonium-vet solution on the indicators of post-vaccination immunity in calves was studied using various vaccines: viral attenuated and inactivated, inactivated bacterial. The effect of these preparations on various links of the immune system, the tension and duration of post-vaccination immunity is determined.


Introduction
Infectious diseases of cattle are widespread in many countries. Pathogens affecting the mucous membranes of the respiratory and gastrointestinal tract cause huge economic damage to livestock, leading to mortality, a decrease in the growth rate of sick animals, the cost of treatment, diagnosis, prevention, and further productivity loss by 10-15% compared with not sick analogues [1,2].
Most factor diseases develop against the background of adverse effects on animals of various predisposing factors that reduce the general nonspecific resistance of the body, have an infectious nature.
In the Russian Federation, as in other countries with developed livestock breeding, acute viral diseases of the respiratory and digestive organs of cattle are widespread, often leading to outbreaks that cause significant economic damage. Respiratory diseases of young cattle of various genesis develop, as a rule, against the background of secondary immunodeficiency states. [3,4].
The root cause of 90% of infectious pneumonia in calves is viruses that cause an infectious process in the respiratory tract, reduce the parameters of systemic immunity and form optimal conditions for the life of bacteria in it [5,6].
For the prevention of acute respiratory viral infections in cattle, viral vaccines, both inactivated and attenuated, are widely used. According to our data, the effectiveness of immunoprophylaxis of acute respiratory viral infections in cattle rarely exceeds 70%, regardless of the type of vaccine. When studying the tension of post-vaccination immunity against respiratory viral infections its deficiency was revealed in 20-25% of animals [7.8].
In the light of the above, the importance of correction of immunity in the treatment and prevention of diseases of farm animals of various origins can hardly be overestimated [8,9].
Under the conditions of industrial management of the industry, low resistance developing against the background of secondary immunodeficiencies is the main cause of morbidity and mortality of productive animals. Predisposing factors of these immunodeficiency states are violations of the standards of technology for keeping, operating and feeding.
Immunobiological methods for monitoring the tension of immunity, the general immunobiological state of animals at various stages of the technological cycle should become part of the system of veterinary and preventive measures in industrial animal husbandry [10,11].
To increase the tension and duration of post-vaccination immunity, the use of immunomodulators of various classes is indicated. [12,13].
However, the currently used vaccines aimed at the prevention of respiratory diseases in cattle of viral, bacterial and mixed etiology are not equivalent: both inactivated and attenuated biological products are used. The effect of immunomodulators of various classes on the tension of post-vaccination immunity with the use of various types of vaccines has not been studied enough, especially in modern livestock breeding conditions. [14.15].
Respiratory diseases of calves occupy one of the leading places among the pathologies common among cattle in the Russian Federation. In the farms of the Krasnodar Territory, from 30 to 65% of calves are sick with respiratory diseases annually, mortality for this reason is 10.2-31%.
The terms of calf disease coincide with the so-called "technological" age-related immunodeficiency and are massive.

Materials and methods
Serological, hematological and immunological studies were carried out in the Department of Therapy and Obstetrics of the Krasnodar Research Veterinary Institute; research and production experiments were carried out on three farms of the Krasnodar Territory: Agrarian Enterprise named after Lukyanenko, Krasnoarmeysky district, LLC "Agrofirm "Khutorok", Private farm "Budyak" of the Timashevsky district on young cattle of 1.5-2 and 4-6 months of age.
All calves (60 animals) selected in each experiment series were divided into 3 groups of 20 animals by the principle of analogue pairs: 2 experimental and 1 control. Before the start of the experiment, blood and nasal outflows were taken from 10 calves of each group for background studies.
The calves of 1 experimental groups were injected subcutaneously with Imactin, at a dose of 1.5 mg / kg body weight; calves of 2 experimental groups intramuscularly -Polyoxidonium-vet solution in a dose of 0.15 mg / kg body weight; the calves of the control groups intramuscularly -sterile saline at the rate of 2.0 cm 3 . Immunocorrectors and saline were administered twice, with an interval of 3 days.
Three days after the last injection of drugs and saline, the calves of the experimental and control groups were vaccinated according to the instructions for the use of biological products: the first series of experiments with the inactivated vaccine "Combovac-R", second series of experimentswith the attenuated vaccine of "Trivaс", third series of experimentswith inactivated vaccine "Kolivaс".
Serological studies were carried out in the hemagglutination inhibition reaction (HAIR), non-direct hemagglutination reaction (NHAR) agglutination reaction (RA) by generally accepted methods; classes of immunoglobulins -according to the Mancini method.
Complex hematological analysis was performed on an automated analyzer "Mythic 18 vet" (Switzerland), erythrocyte sedimentation rate (ESR) -by the Panchenkov method; quantitative assessment of lymphoid elements -using a hematological electronic digital counter, according to the guidelines for veterinary hematology.
The aim of the research was to study the effect of immunocorrector of various pharmacological groups on the post-vaccination immunity of cattle using various types of vaccines: inactivated and attenuated viral, inactivated bacterial. To determine their effect on various parts of the immune system, the duration and tension of post-vaccination immunity.
To achieve the goal, the following tasks are identified for study: -to study the effect of immunomodulators on the tension and duration of postvaccination immunity in cattle using an inactivated antiviral vaccine; -to study the effect of immunomodulators on the tension and duration of postvaccination immunity in cattle using an attenuated antiviral vaccine; -to study the effect of immunomodulators on the tension and duration of postvaccination immunity in cattle using an inactivated bacterial vaccine.

Results
As a result of the studies, it was found that before vaccination in calves the average titers of specific antibodies in HAIR to PI-3, in NHAR to IRT and VD-MMD were in the range of 1: 12.2 ± 4.6; 1: 4.6 ± 2.1 and 1: 2.1 ± 0.6 with fluctuations from 1: 2 to 1:32 in both the control and experimental groups. A month after vaccination, the titers of specific antibodies to PI-3 in the experimental groups increased 12-11.6 times to PI-3, 8.3-8.8 times for IRT and 7.9-8.2 times to VD-MMD, in control -7.4 times. The titers of specific antibodies to PI-3 in the firstt experimental group exceeded the control by 75%, in the second experimental group -by 45.4%, with titer fluctuations from 1:16 to 1: 256. The titers of specific antibodies to IRT and VD-MMD were lower and ranged from 1: 38.18 ± 12.4 and 34.3 ± 9.1, respectively, and exceeded the control indices by 29.8 -16.6%. A similar trend continued 2 and 3 months after vaccination. Three months after vaccination, tense postvaccination immunity was detected in 60% of calves of the first experimental group, 70% in the second and 40% in the control. Average antibody titers in the experimental groups exceeded those in the control to PI-3 -158.8% and 317%; to IRT -122% and 88%; to VD-MMD -25% and 34.8%. The results of the studies are presented in Table 1.
Thus, the use of immunomodulators in vaccinating calves with the inactivated virus vaccine "Combovac-R" increases the tension and duration of post-vaccination immunity. When assessing the effect of immunostimulants on the indices of specific secretory antibodies of the respiratory tract, it was found that immunization did not cause their increase in both the experimental and control groups, they remained at the level of background values: to PI-3 -1: 1.2 ± 0.6; to IRT -0.4 ± 0.4; VD-MMD -0.
Analyzing the morphological parameters, it was found that the calves of the experimental groups showed a 6-6.8% increase in the number of leukocytes, while the relative number of neutrophils in the blood of the calves of the experimental groups was not significantly changed, which indicates the absence of an inflammatory process, while in the control their number has increased significantly. A significant increase in the activity of neutrophils by 26.4% and 21.2% was in the experimental groups compared with the control. In the first experimental group, the amount of hemoglobin significantly increased on the 30 th day after vaccination, in the second experimental group -hematocrit. The remaining indicators did not significantly change.
When studying the effect of immunological parameters on day 30 after immunization, the absence of a significant increase in the relative number of T and B lymphocytes in the blood was found, but their ratio normalized. There was a significant increase in the activity of neutrophils by 26.4% and 21.2% in the experimental groups compared to the background values and by 17.4% in the first experimental group and 11.1% in the second experimental group. In the second experimental group, the number of farmazin positive phagocytes has significantly increased, and the ACI (average cytochemical index) increased.
The effect on the humoral immunity is expressed in an increase in SBA (serum bactericidal activity) by 59.5-63.1%, SLA (serum lysozyme activity)by 31.9-47.3%, against the control group, where these indicators increased by 9.0 and 6.3%, respectively. The results of the studies are presented in Table 4.
In the second experimental group, a significant increase in serum of calves of IgG was noted -by 13, 3% and Ig M by 10.5%.
On 60 and 90 days after vaccination, there were no significant differences in the indices of cellular and humoral immunity in animals of the experimental and control groups.
Thus, the use of immuno-modulators of Polyoxidonium-Vet solution and Imactin for vaccination of calves with the inactivated virus vaccine "Combovac-R" helps not only activate immunogenesis, but also normalize the morphological blood values, increase the activity of cellular and humoral parts of the immune system.
In the second series of experiments conducted on the basis of MTF No. 6 of Agrofirm Khutorok LLC in the Timashevsky district, using the attenuated Trivak vaccine, similar results were obtained, but specific antibody titers in serum and nasal secretions were higher; a significant increase in the amount of Ig A and G was noted in nasal secretions of calves of all groups, and in the experimental groups, these indicators exceeded the control values by 46.3 and 37.8%. The results of serological studies are presented in Table 2. As it can be seen from the table, the highest titers of specific antibodies to PI-3 were noted 30 days after the last vaccination, and in the first experimental group they were higher than in the control 3. The titers of specific antibodies and immunoglobulins in the nasal secretions of calves are presented in Table 3.
As it can be seen from the data in table 3, in nasal secretions of calves, the maximum titers of specific antibodies to PI-3 in the experimental groups were recorded on the 60 th day after immunization -1: 32.1 and 1: 26.3, in the control group -on the 30 th day after immunization -1: 16.4. By the 90 th day after immunization, the titers of secretory antibodies decreased, but were 2 times higher than background values and 2.4-3 times higher than control values (1: 2.4). A similar picture was observed with respect to secretory specific antibodies to IRT and VD-MMD. Secretion immunoglobulins after vaccination reached their maximum values in the experimental groups also on day 60, in the controlon the 30th, IgG -on the 60th, but there were no significant differences compared with the level observed on day 30. By day 90 after vaccination, immunoglobulin levels returned to baseline values.
As it can be seen from the data in Table 7, in white blood cells values in animals of the experimental groups, there was a significant by 29.3 -28.8% decrease of leukocytes, while in the control group this indicator decreased by 17.3%. In parallel, in the experimental groups, a decrease in the absolute and relative number of neutrophils was noted, which indicates the extinction of the inflammatory process. Insignificant eosinophilia was detected in animals of the control group, which may indicate an allergic component in the development of a viral infection, which is not observed in the experimental groups. The red blood picture indicates an activation of hematopoiesis in animals of the experimental groups, while in the control the growth of these values was not significant: 28.1% in the first experimental group, 13.0% in the second experimental group and 9.5% in the control.
When analyzing the results of immunological studies, a positive dynamics of the indicators of the phagocytic link was noted: the phagocytic activity of neutrophilic granulocytes in the blood increased by 43.2-67% compared to background values, in the control -by 24%. The activity of the microbicidal system of oxygen-dependent phagocytosis according to the NBT test was higher than the control value by 18.6 and 21.5%, the completion rate of phagocytosis increased to 1.1-1.2, which indicates its completion, while in the control this value was below 1 -phagocytosis is not completed.
By the cellular link, a decrease in the total number of lymphocytes T and B, a normalization of their ratio, was noted. According to the humoral link there was a significant increase in IgG and IgM in blood serum by 9.2-11.6% and 4.8-7.4%, respectively. The lysozyme activity of blood serum in animals of the experimental groups increased by 63.6 and 90.6%, bactericidal activity -77.2 and 51.5, in the control group -by 12.8 and 19.6%, respectively. The third series of experiments was carried out on a private farm in the Timashevsky district of IE Vorokhobin Yuri Yurievich on 20-25-day-old calves of Holstein and Ayrshire breeds, which were vaccinated against the background of the introduction of immunomodulators with the inactivated Kolivac vaccine.
Serological studies in RA found that the average titers of specific antibodies to E. coli K-99 / O157 in the first experimental group on the 30 th day after vaccination reached a value of 1: 198.2, which is 29.5 times more than the background and 87% -of control. In the second experimental group, these values were respectively 35.2 and 93%. The results of the studies are presented in Table 4. On the 90th day after vaccination in the control group, only 20% of calves had titers of specific antibodies to E. coli K-99 / O157 higher than 1:16, which protects animals; in the first experimental group there were 70% of calves with post-vaccination immunity tense; in the second -85%.
Thus, when using the Kolivac inactivated bacterial vaccine, the use of immunomodulators can increase the post-vaccination immunity tense by 87-93% compared with the control and the duration -by 52-64%.

Discussion
Analyzing the obtained data, we found the absence of significant differences in background indicators in calves of the experimental and control groups. Thirty days after vaccination, the amount of hemoglobin in the second experimental group increased by 12.3%, PhA (phagocytic activity), SBA and MF (mobilization factor).
The number of lymphocytes in calves of the experimental groups decreased in reference values due to an increase in neutrophils, which is characteristic of the immune response to vaccination. SBA in animals of the experimental groups increased on average by 45% compared to the background and was higher by 40.1 -97% in relation to control animals. A similar picture is observed in the assessment of PhA and MF.
The performed experimental studies suggest that in different age groups of calves (1-1.5-month old and 4-6-month old) with acute respiratory viral infections (PI-3 and IRT association and PI-3 monoinfection) in the system of therapeutic measures the use of immunocorrectors of polyoxydonium-vet solution and imactin has a positive effect on the performance of the phagocytosis system, increasing the phagocytic activity of blood neutrophils by 70.1-92.4% compared to the background values and by 19.5-41.2 to the control group, in calves of younger age and by 43.2-67% compared with the background values in calves of older age. The digesting activity of phagocytes according to the NBT test increases by 9.5-12.3% and 18.6-21.5%, respectively.
Immunocorrectors activate hematopoiesis in older calves, while in animals of the experimental groups of 1-1.5 month old, there were no significant changes in the red blood picture compared with control animals.

Conclusions
The use of immunocorrectors contributes to the activation of general and local humoral immunity.
New knowledge has been gained on the effect of immunocorrectors on the parameters of cellular, humoral and local immunity in young cattle in case of respiratory viral infections.