Structural and functional characteristics of immunoglobulins of the common domestic species

Importance of antirabies revaccination for an adequate antirabies protection in bovine newborns

The transfer of antirabies immunoglobulins in cows that were prime vaccinated and cows that were revaccinated against rabies correlated to the serum titers in their offspring was evaluated. The results demonstrated that revaccination against rabies during pregnancy induces neutralizing antibody titers at a protective level that are transferred directly to calves through colostrum and reinforce the importance of revaccination for improved colostral antibody transfer and offspring protection against rabies.

The mammary gland and neonate mucosal immunity

The passive mucosal protection of neonate mammals is dependent on the continuous supply until weaning of maternally dimeric IgA (monogastric) and IgG1 (ruminants). This lactogenic (humoral) immunity is linked to the gut, the so-called entero-mammary link, because of the translocation of Ig (IgA and IgG1) or the emigration of IgA lymphoblasts from the gut into the mammary gland (MG); on the other hand, studies on the lymphocyte subsets in the MG of artiodactyls sustained the view of a true local immune response, depending on the MG stage development. Accordingly, the increase of the lactogenic immunity may focus on (1) inductor sites (gut and, possibly, the MG), (2) increase in cell traffic from the gut into the MG, and (3) enhancement at the effector site of the Ig production and excretion in milk. A specific mucosal environment (interleukins and hormones) is responsible for IgM/IgA switch, the induction of mucosal homing receptor onto lymphoblasts and mucosal vascular addressins; very few data are available for the mechanism of lymphoblasts recruitment, either IgA or IgG1, although lactogenic hormones have been implicated in the IgA-blasts homing into the mice MG. After weaning, the neonate is able to mount a gut immune response, but the shortage of the suckling period did not seem to be detrimental for its onset. In soyabean allergy, both piglet and calf exhibited gut villus atrophy, gut accumulation of IgA (swine) and IgG1 (cattle) immunocytes, sustaining the view that a specific environment in ruminant is responsible for both IgA and IgG1 production.

Estimation of antibodies to Newcastle disease virus in tears

Micro-haemagglutination inhibition tests (Micro-HI) were used to measure the level of maternal IgG in the tears of chicks and also to measure the levels of HI antibodies in the tears and serum after vaccination with "F" strain of Newcastle disease virus (NDV) and in the face of an outbreak of Newcastle disease. There was a 1.4 fold difference between the maternal IgG concentration in the serum and tears. The ratio of serum IgG to lachrymal IgG after maternal transfer was 4 to 5:1 on day 4 to 9 and decreased to 2.6:1 on day 12 post-hatch. The intra-ocular vaccination of chicks with "F" strain of NDV resulted in the highest titre of HI antibodies in the tears though there was no significant difference in the response of chicks vaccinated through intranasal, oral and intravenous routes. In the face of an ND outbreak, the level of HI antibodies in the tears during the acute phase was very high and persisted at the same level for 14 days.

Passive transfer of mucosal antibody to Streptococcus equi in the foal

Passive transfer of mucosal antibody to Streptococcus equi was studied in foals during the first 2 months of life. Immunoglobulin G (IgG) and IgA antibodies were found in sera and nasal secretions of foals shortly after colostrum intake. Titers were highest 2 days after birth; IgG predominated in sera, and IgA predominated in nasal washes. Intragastrically administered 99mTc-labeled IgA was transported from the bloodstream to the nasal mucosa of a newborn foal within a few hours of colostrum intake. Western blot analysis of the specificities of colostral and serum antibodies showed that selective transfer of immunoglobulins of defined specificity did not occur. Antibodies from milk samples taken a month or more into lactation had different specificities than those of colostrum or serum samples. Acid-extracted M protein fragments of S. equi recognized by milk antibodies were the same as those recognized by IgG and IgA from nasopharyngeal mucus of horses recently recovered from strangles. We postulate that passive antibody protection of the foal is derived both by secretion of colostral immunoglobulins onto the nasopharyngeal mucosa and by immunoglobulins ingested in milk that directly coat the upper respiratory and oral mucosa during the first months of life.