Impact of maternally derived immunity on piglets’ immune response and protection against porcine circovirus type 2 (PCV2) after vaccination against PCV2 at different age

BACKGROUND: This study was aimed at evaluating the clinical protection, the level of Porcine circovirus type 2 (PCV2) viremia and the immune response (antibodies and IFN-γ secreting cells (SC)) in piglets derived from PCV2 vaccinated sows and themselves vaccinated against PCV2 at different age, namely at 4, 6 and 8 weeks. The cohort study has been carried out over three subsequent production cycles (replicates). At the start/enrolment, 46 gilts were considered at first mating, bled and vaccinated. At the first, second and third farrowing, dams were bled and re-vaccinated at the subsequent mating after weaning piglets. Overall 400 piglets at each farrowing (first, second and third) were randomly allocated in three different groups (100 piglets/group) based on the timing of vaccination (4, 6 or 8 weeks of age). A fourth group was kept non-vaccinated (controls). Piglets were vaccinated intramuscularly with one dose (2 mL) of a commercial PCV2a-based subunit vaccine (Porcilis® PCV). Twenty animals per group were bled at weaning and from vaccination to slaughter every 4 weeks for the detection of PCV2 viremia, humoral and cell-mediated immune responses. Clinical signs and individual treatments (morbidity), mortality, and body weight of all piglets were recorded. RESULTS: All vaccination schemes (4, 6 and 8 weeks of age) were able to induce an antibody response and IFN-γ SC. The highest clinical and virological protection sustained by immune reactivity was observed in pigs vaccinated at 6 weeks of age. Overall, repeated PCV2 vaccination in sows at mating and the subsequent higher levels of maternally derived antibodies did not significantly interfere with the induction of both humoral and cell-mediated immunity in their piglets after vaccination. CONCLUSIONS: The combination of vaccination in sows at mating and in piglets at 6 weeks of age was more effective for controlling PCV2 natural infection, than other vaccination schemas, thus sustaining that some interference of MDA with the induction of an efficient immune response could be considered. In conclusion, optimal vaccination strategy needs to balance the levels of passive immunity, the management practices and timing of infection.

Genetically attenuated, P36p-deficient malarial sporozoites induce protective immunity and apoptosis of infected liver cells.

Immunization with Plasmodium sporozoites that have been attenuated by gamma-irradiation or specific genetic modification can induce protective immunity against subsequent malaria infection. The mechanism of protection is only known for radiation-attenuated sporozoites, involving cell-mediated and humoral immune responses invoked by infected hepatocytes cells that contain long-lived, partially developed parasites. Here we analyzed sporozoites of Plasmodium berghei that are deficient in P36p (p36p(-)), a member of the P48/45 family of surface proteins. P36p plays no role in the ability of sporozoites to infect and traverse hepatocytes, but p36p(-) sporozoites abort during development within the hepatocyte. Immunization with p36p(-) sporozoites results in a protective immunity against subsequent challenge with infectious wild-type sporozoites, another example of a specifically genetically attenuated sporozoite (GAS) conferring protective immunity. Comparison of biological characteristics of p36p(-) sporozoites with radiation-attenuated sporozoites demonstrates that liver cells infected with p36p(-) sporozoites disappear rapidly as a result of apoptosis of host cells that may potentiate the immune response. Such knowledge of the biological characteristics of GAS and their evoked immune responses are essential for further investigation of the utility of an optimized GAS-based malaria vaccine.

Smallpox immunity in 5000 students,

Mode of access: Internet.

Design of a high noise immunity analog frequency counter /

"UIUCDCS-R-73-595"

Collected studies on immunity /

Translation of his Gesammelte Arbeiten zur Immunitätsforschung.

Studies in vaccinal immunity towards disease of the bovine placenta due to bacillus abortus (infectious abortion) /

"November 15, 1923"--Cover.

A practical text-book of infection, immunity and biologic therapy / with special reference to immunologic technic /

Mode of access: Internet.

An outline of lectures on pathogenic bacteriology and immunity with relation to the domestic animals; Course 49, New York State Veterinary College at Cornell University, Ithaca, New York,

"Some reference books likely to be useful to students in this course": p. xi.

An outline of lectures on pathogenic bacteriology (veterinary) and immunity. Course 49, New York State Veterinary College at Cornell University.

Manifold copy (photo-litho offset)

An outline of lectures on pathogenic bacteriology (veterinary) and immunity; Course 49, New York State Veterinary College at Cornell University.

Mode of access: Internet.

Certain problems of immunity in helminthology,

Translated from Izvestiva Akademii Nauk SSSR, Biological Series, 1963, 28(4):504-13.

Nicarbazin. Pt. 2, The development of immunity to coccidiosis during preventive medication with nicarbazin.

Mode of access: Internet.

Anthrax : with special reference to the production of immunity /

Mode of access: Internet.

Further experiments concerning the production of immunity from hog cholera /

"January 18, 1908."

Sovereign immunity : hearing before the Committee on Indian Affairs, United States Senate, One Hundred Fifth Congress, second session : oversight hearing to provide for Indian legal reform.

Shipping list no.: 98-0327-P (pt. 1).