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Reproductive failure occurred in a swine herd in which the epizootiology of enteroviruses and the porcine parvovirus were being studied. Three virgin boars that were seropositive for the parvovirus were mated to seronegative, previously unmated gilts. The 11 gilts that farrowed had small litters, with high perinatal mortality. The remaining 12 gilts were marketed because of infertility, and the reproductive tracts were examined. Pathologic findings included early embryonal death attributed to viral infection. After the reproductive failure, all gifts and boars were seropositive for the parvovirus, suggesting that the reproductive failure was associated with a parvovirus infection.

Reich, C. V. (Pennsylvania State University, University Park), C. E. Heist, and H. W. Dunne. Agglutinin-adsorption analysis of Vibrio fetus. J. Bacteriol. 82:210-214. 1961.-All pathogenic strains of Vibrio fetus are apparently members of a single serotype. Within this broad grouping, it was possible to define the relationship of certain selected strains by a system of complete reciprocal adsorption and cross agglutination. Formalin treated suspensions of V. fetus, and controlled titer homologous rabbit antisera were used. The results of a set of reactions, involving five strains, were analyzed as a complete reaction pattern. A system of 12 antigens and 4 haptens, each alphabetically characterized, was necessary to reproduce schematically the experimentally obtained reaction pattern. One of the antigens, designated as antigen A, was a somatic antigen present on every strain of V. fetus examined. Evidence indicates that this antigen represented about 5% of the total antigenic area of the cell surface.

SMEDI and hog cholera viruses were shown to have marked effects upon the survival of the embryo (from conception to 30 days of gestation), the fetus (from 30 days of gestation until birth), and the neonatal pig (from birth until five days after birth). Embryonic infection was characterized by death and absorption of the embryo and in some instances the return to estrus after an irregular estrous cycle. Embryonic infection also may have been responsible for the development of some abnormal pigs. Fetal infection caused death with mummification of one or more fetuses and occasionally all fetuses in the uterus. Infection established in early gestation produced effects on the fetus which apparently persisted until after birth and varied from a persistent viremia (as in hog cholera infection) to an undefined lack of resistance in the newborn (as in SMEDI virus infection). Hog cholera vaccinal virus was the more virulent of the two virus types and reacted somewhat like rubella virus, in that infection apparently could be established in the fetus even in middle trimester of pregnancy, and possibly later. SMEDI viruses, in contrast, were less virulent and were most pathogenic when the dam was infected during the first 30 days of pregnancy. Immunity against either virus could be established in the nonpregnant gilt and was most effective in preventing intrauterine infections with that virus. However, with as many as 10 enteroviruses (five are known to cause intrauterine infection) it was believed that maintaining a closed breeding herd and introducing new stock into contact with the breeding herd at least 30 days before breeding time might be a safer means of control.

Hematological values of peripheral blood were determined for bovine fetuses and calves of various ages. Erythrocyte values increased through gestation. Fetuses 100 days or older had total values within the ranges of those reported for normal adult cattle. Mature erythrocytes were not observed in embryos and only a few were observed in fetuses 40 days of age. Fetuses 250 days or older had only a few rubricytes (<10/100 WBC). Leukocytes were first identified in the peripheral blood of a 45-day old fetus. Absolute leukocyte values increased through gestation and reached maximum values shortly before parturition. Granulocytes were first observed at 130 days of gestation and reached maximum values near parturition. Total serum protein and gamma-globulin concentrations of colostrum-deprived calves were similar to serum protein and gammaglobulin concentrations of fetuses older than 265 days and were lower than values for the colostrum-fed calves. The immunoelectrophoretic pattern of 59-day old fetuses, the earliest age at which serum samples were obtained, demonstrated albumin, an alpha1 globulin and a beta globulin, possibly transferrin. Additional alpha and beta globulins appeared in the older fetuses and by 175 days of gestation serum electophoretic patterns of the fetuses were similar to patterns normally found with adult bovine serum except for the absence of the gammaglobulins in fetal serum. Immunoglobulin M was detected in 39 of 95 fetal serum samples by radial diffusion and in 13 of 95 samples by immunoelectrophoresis. Immunoglobulin G was detected in ten of 95 fetal serum samples by radial diffusion and in six of 95 samples by immunoelectrophoresis.

The ontogenesis of the bovine immune response was studied in three embryos (<40 days) and 106 fetuses of various ages. In the absence of overt antigenic stimulation, fetuses had lymphoid development of the thymus at 42 days of gestation, the spleen was structurally present at 55 days, and certain peripheral lymph nodes were present at 60 days. Mesenteric lymph nodes were structurally present by 100 days of gestation, and lymphoid tissue of the gastrointestinal tract, particularly the lower ileum, was observed in histologic sections of a 175-day fetus with a bacterial infection. Pyroninophilic cells, plasma cells, and germinal centers were present in lymph node sections of antigenically stimulated fetuses. Lymphoid tissue developed more rapidly in fetuses with bacteria, viral antigens, or apparent maternal red-blood-cell antigens than in the normal fetus. Thymic and splenic indices reached maximal values in the 205- to 220-day fetal age group. Immunoglobulin M (IgM)-containing cells were first observed, by immunofluorescence, in a single fetus at 59 days of gestation. Immunoglobulin G (IgG)-containing cells were observed at 145 days of gestation in one fetus with a bacterial and viral infection. IgM-containing cells were observed in 36 fetuses and IgM and IgG cells were present in seven fetuses. Spleen, lymph nodes, thymus, bone marrow, and liver of one fetus from a dam with lymphosarcoma had immunoglobulin-containing cells. Hemal lymph nodes, blood (buffy coat), Peyer patches, and heart and lung sections from fetuses with immunoglobulin-containing cells in spleen or lymph node did not have immunoglobulin-containing cells. Antigens of the virus of bovine virus diarrhea-mucosal disease (BVD) were detected in one fetus, and antigens of infectious bovine rhinotracheitis (IBR) virus were detected in three fetuses; however, viruses were not isolated in primary bovine embryonic kidney cells. Two of the three fetuses with IBR virus antigens had neutralizing serum antibody titers to IBR virus. Bacteria including Escherichia coli, Lactobacillus sp. and Mima polymorpha var. oxidans were isolated from four fetuses. Antibodies that caused the agglutination of maternal red blood cells were present in 8 of 20 bovine fetal serum samples. The antibodies were 2-mercaptoethanol sensitive and partially heat resistant (56 C for 30 min). The ontogeny of the bovine immune response and human immune response were compared, and it was suggested that the similarities were primarily due to the two species having the same approximate gestation period of 280 days.