Protection of agammaglobulinemic piglets from porcine rotavirus infection by antibody against simian rotavirus SA-11

Impact of colostrum and plasma immunoglobulin intake on hippocampus structure during early postnatal development in pigs

The first milk, colostrum, is an important source of nutrients and an exclusive source of immunoglobulins (Ig), essential for the growth and protection from infection of newborn pigs. Colostrum intake has also been shown to affect the vitality and behaviour of neonatal pigs. The objective of this study was to evaluate the effects of feeding colostrum and plasma immunoglobulin on brain development in neonatal pigs. Positive correlations were found between growth, levels of total protein and IgG in blood plasma and hippocampus development in sow-reared piglets during the first 3 postnatal days. In piglets fed an elemental diet (ED) for 24h, a reduced body weight, a lower plasma protein level and a decreased level of astrocyte specific protein in the hippocampus was observed, as compared to those that were sow-reared. The latter was coincident with a reduced microgliogenesis and an essentially diminished number of neurons in the CA1 area of the hippocampus after 72h. Supplementation of the ED with purified plasma Ig, improved the gliogenesis and supported the trophic and immune status of the hippocampus. The data obtained indicate that the development of the hippocampus structure is improved by colostrum or an Ig-supplemented elemental diet in order to stimulate brain protein synthesis and its development during the early postnatal period.

Bovine milk antibodies for health

The immunoglobulins of bovine colostrum provide the major antimicrobial protection against microbial infections and confer a passive immunity to the newborn calf until its own immune system matures. The concentration in colostrum of specific antibodies against pathogens can be raised by immunising cows with these pathogens or their antigens. Immune milk products are preparations made of such hyperimmune colostrum or antibodies enriched from it. These preparations can be used to give effective specific protection against different enteric diseases in calves and suckling pigs. Colostral immunoglobulin supplements designed for farm animals are commercially available in many countries. Also, some immune milk products containing specific antibodies against certain pathogens have been launched on the market. A number of clinical studies are currently in progress to evaluate the efficacy of immune milks in the prevention and treatment of various human infections, including those caused by antibiotic resistant bacteria. Bovine colostrum-based immune milk products have proven effective in prophylaxis against various infectious diseases in humans. Good results have been obtained with products targeted against rotavirus, Shigella flexneri, Escherichia coli, Clostridium difficile, Streptococcus mutans, Cryptosporidium parvum and Helicobacter pylori. Some successful attempts have been made to use immune milk in balancing gastrointestinal microbial flora. Immune milk products are promising examples of health-promoting functional foods, or nutraceuticals. This review summarises the recent progress in the development of these products and evaluates their potential as dietary supplements and in clinical nutrition.

Correlation between maternal serum antibodies and protection against bovine rotavirus diarrhea in calves

The correlation between maternal serum antibodies in beef calves at 2 days old and protection against diarrhea induced by natural bovine rotavirus (BRV) infection was examined. Virus neutralizing (VN) antibody titers against BRV in sera from calves that developed diarrhea by BRV infection within 14 days of age (BRV-diarrheal calves) were significantly lower than those from calves that had no diarrhea. In the BRV-diarrheal calves, a positive correlation was found between the VN antibody titers and age of the onset of diarrhea. There were negative correlations between the VN antibody titers and duration of the diarrhea, VN antibody titers and cumulative diarrhea scores, and the VN antibody titers and duration of virus shedding. These results suggest that the VN antibody titers against BRV in newborn calf serum could be an indicator of protection against BRV-induced diarrhea.

Passive immunity against rotavirus in infants

Passive immunity against a variety of gastrointestinal infections, using orally administered human antibodies, has been tried in a number of clinical trials. Recently, antibodies from other species such as cows and chickens, which have shown efficacy in experimental animal systems, have also been tried in humans. This review summarizes published data on the use of immunoglobulin-containing preparations for prophylaxis and therapy against rotavirus infections in infants and children, and directions for their future use are suggested.

Human serum immunoglobulin counteracts rotaviral infection in Caco-2 cells

Oral administration of human serum immunoglobulin reduces the duration of diarrhea and of rotaviral excretion in children. To investigate the in vitro effects of immunoglobulin on virus-enterocyte interaction, Caco-2 cells were infected with Rotavirus strain SA11. Immunoglobulin was added prior to and at various times postinfection. Indirect immunofluorescence was performed with an antibody against VP-6 rotaviral antigen. Cell viability and monolayer transepithelial electrical resistance (TEER) were monitored. Immunofluorescence showed a perinuclear distribution in 90% of cells. Rotavirus infection induced a progressive decrease in TEER and a parallel reduction in cell viability, depending on viral load. Preincubation of the virus with immunoglobulin prevented cell infection as judged by immunofluorescence. Immunoglobulin addition to infected cells partially prevented the decrease in TEER and induced a later shift of TEER toward increasing values, suggesting restoration of monolayer's integrity. The efficacy of immunoglobulin depended on its concentration and on the time of its addition. These results indicate that immunoglobulin is effective in preventing infection and in reducing cell damage, through a direct anti-Rotavirus action and may indicate that immunoglobulin should be administered in the early phase of diarrhea, to reduce the severity of Rotavirus infection.

Bovine antibody against Cryptosporidium parvum elicits a circumsporozoite precipitate-like reaction and has immunotherapeutic effect against persistent cryptosporidiosis in SCID mice

Control of cryptosporidiosis is currently hampered by the absence of drugs or vaccines proven consistently effective against Cryptosporidium parvum. On the basis of observations that anti-C. parvum antibody has therapeutic effect against cryptosporidiosis, cows were immunized with C. parvum to produce hyperimmune colostral antibody. An antibody-rich fraction was prepared and differentiated from control (nonhyperimmune) antibody by enzyme-linked immunosorbent assay, immunofluorescence assay, immunoelectron microscopy, and in vitro neutralizing titer against DEAE-cellulose-isolated C. parvum sporozoites. Oocyst, purified sporozoite, and merozoite antigens recognized by hyperimmune antibody were defined by Western blot (immunoblot). Hyperimmune antibody recognized antigens common to oocysts, sporozoites, and merozoites, as well as stage-specific antigens. Upon incubation with hyperimmune antibody, sporozoites underwent distinct morphologic changes characterized by progressive formation and eventual release of membranous sporozoite surface antigen-antibody complexes, similar to the malaria circumsporozoite precipitate reaction. The infectivity of sporozoites having undergone this reaction was neutralized. The reaction was minimal or absent on sporozoites incubated with control antibody. To determine therapeutic effect in vivo, persistent C. parvum infection was established in adult severe combined immune-deficient (SCID) mice by oral inoculation with 10(7) oocysts. At 5 weeks postinfection, infected mice were treated for 10 days with hyperimmune or control antibody by inclusion in drinking water and daily gavage. Fecal oocyst shedding and infection scores in the gastrointestinal tract and gall bladder/common bile duct in hyperimmune antibody-treated mice were significantly lower than those in the control antibody-treated mice. Hyperimmune bovine antibody prepared against C. parvum may provide a first-generation therapy for control of cryptosporidiosis. Additionally, the defined antigens can be evaluated as subunit immunogens to produce better-characterized polyclonal antibody for control of cryptosporidiosis or as targets for monoclonal antibody-based immunotherapy.

Rotaviruses: immunological determinants of protection against infection and disease

Although studies of rotavirus immunity in experimental animals and humans have often yielded conflicting data, a preponderance of evidence supports the following answers to the questions initially posed. 1. What is the importance of virus serotype in formulating an optimal vaccine? Both vp4 and vp7 induce virus-neutralizing antibodies after either natural infection or immunization; the capacity of vp4 to induce rotavirus-specific neutralizing antibodies is probably greater than that of vp7. However, protection against disease after immunization of infants and young children is induced by strains heterotypic to the challenge virus (e.g., immunization with WC3 induces protection against disease induced by serotypically distinct human G1 strains). In addition, oral inoculation of infants with primate or bovine reassortant rotaviruses containing genes that encode human vp7 has not consistently induced a higher level of protection against challenge than that induced by parent animal rotaviruses (see Table I). Therefore, although vp4 or vp7 or both are probably important in inducing protection against challenge, it has not been clearly demonstrated that inclusion of the epidemiologically important human (as distinct from animal) P or G type is important in protection against human disease. 2. Which immunological effector arm most likely protects against rotavirus disease? No immunological effector arm clearly explains protection against heterotypic challenge. Protection against disease is not predicted by rotavirus-specific neutralizing antibodies in serum. Rotavirus-specific, binding sIgA in feces [detected by enzyme-linked immunosorbent assay (ELISA)] induced after natural infection does correlate with protection against disease induced by subsequent infection. However, protection after immunization with WC3 may occur in the absence of a detectable fecal sIgA response. The relationship between rotavirus-binding sIgA and sIgA-mediated neutralizing activity directed against the challenge virus remains to be determined. Binding rotavirus-specific sIgA in feces detected by ELISA may only be a correlate of other events occurring at the intestinal mucosal surface. The presence of broadly cross-reactive, rotavirus-specific CTLs at the intestinal mucosal surface of mice acutely after infection is intriguing. It would be of interest to determine the degree to which the presence of cross-reactive, rotavirus-specific CTLs in the circulation is predictive of the presence of virus-specific CTLs among intestinal lymphocytes and protection against challenge. Unfortunately, studies of virus-specific CTLs are difficult to perform in children. 3. By what means is virus antigen best presented to the host to elicit a protective immune response? Oral inoculation may not be necessary to induce a protective, virus-specific immune response at the intestinal mucosal surface.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunogens of rotaviruses

Rotaviruses cause gastroenteritis in neonates of many animal species including cattle, swine, horses, dogs, cats, chickens and turkeys. Rotavirions are nonenveloped, are about 75 nm in diameter, have a double capsid, and contain 11 double-stranded RNA segments as their genome. Several antigenically distinct groups of rotaviruses have been identified and have been alphabetically designated as A through G. Group A rotaviruses were the first group of rotaviruses isolated and are the most commonly detected rotaviruses in diarrheic animals. Group A rotaviruses have two surface proteins, VP4 and VP7, both of which are important in serotype determination and in inducing neutralizing antibodies and protective immunity. Multiple serotypes of group A rotavirus based on glycoprotein VP7 (designated as G types) and based on VP4 (P types) have been identified. The immune response to rotaviruses is essentially serotype specific, however, cross-reactive or heterotypic epitopes have also been identified. Currently acceptable methods for immunogen quantitation include the induction of neutralizing antibody in host or laboratory animals. The in vivo efficacy of vaccines against rotavirus-associated gastroenteritis remains the standard method against which in vitro methods must be compared. Several animal models have been developed which could potentially be used in evaluating the efficacy of candidate vaccines. Monoclonal antibodies to rotavirus immunogens are also currently available and serve as valuable reagents for in vitro quantitation of rotaviral immunogens.