Two monoclonal antibody-blocking enzyme-linked immunosorbent assays (B-ELISAs) were developed to detect serovar-specific antibodies to Haemophilus paragallinarum. One assay detected antibodies against serovar A and the other antibodies against serovar C. The assays were evaluated with sera derived from disease-free chickens as well as chickens experimentally immunized and/or challenged with H. paragallinarum strains 0083 (serovar A), Modesto (serovar C), or HP31 (serovar C). When tested with 440 negative sera (170 from a specific-pathogen-free and 30 from each of nine commercial layer flocks), both tests gave only a single false-positive reaction. The use of the B-ELISAs with the experimentally produced sera showed the assays to be serovar specific. With the exception of one serum, the serovar A B-ELISA detected antibodies only in the chickens vaccinated with 0083. Similarly, with the exception of one serum, the serovar C B-ELISA detected antibodies only in those chickens vaccinated with Modesto or those chickens challenged with HP31. Overall, the serovar A B-ELISA had a specificity of 99.7% and a sensitivity of 78.7%, whereas the serovar C B-ELISA had a specificity of 99.8% and a sensitivity of 64.7%.
Two new monoclonal antibodies (MAbs), D6D8D5 and B3E6F9, both directed against Haemophilus paragallinarum serovar C hemagglutinating (HA) antigen, were produced, and characteristics of the MAbs were compared with those of the previously described MAb F2E6 in dot-blot and hemagglutination-inhibition (HI) tests using two representative H. paragallinarum strains each of serovars A, B, and C strains and 55 Japanese serovar C field isolates. MAb D6D8D5 and MAb F2E6 reacted with all serovar C strains and field isolates in the dot-blot test. However, MAb D6D8D5 showed various degrees of inhibition of the HA activity of field isolates. In the enzyme-linked immunosorbent assay-competition test, MAb D6D8D5 did not compete with MAb F2E6. MAb B3E6F9 reacted with strain S1, serovar C but not with strain Modesto, serovar C in both dot-blot and HI tests. Three out of 55 field isolates did not react with MAb B3E6F9. Neither MAb reacted with the serovar A and B strains.
Immunogenicity of three Haemophilus paragallinarum serovar B strains was investigated in cross-protection tests using monovalent vaccines prepared from the B strains, as well as one strain each of serovars A and C. A bivalent vaccine composed of the serovar A and C strains also was used. In the studies with the monovalent vaccines, the immunogenicity of serovar B strains was different from that of serovar A and C strains, although only partial serovar B-specific protection with the three strains was observed. Chickens vaccinated with the bivalent vaccine protected against challenge with one serovar B strain, as well as serovar A and C strains, but not against the other two serovar B strains.
Biological activities in chickens of crude polysaccharide extracted from two different immunotype strains of Hemophilus gallinarum (HG), strain 221 and S1, were studied to clarify a type-specific protecting antigen and a toxin. Crude polysaccharide materials extracted from strains 221 and S1 were not only protective but toxic to chickens. They also contained at least two heat-labile antigens. When the polysaccharide materials were subjected to gel filtration on Sepharose 6B by tracing at 280 and 490 nm, the protective and toxic activities could be fractionated as peak-1 and -2 polysaccharides, respectively. The fraction of peak-1 polysaccharides from strains 221 and S1 was eluted at void volume. Cross-protection was not found between strains 221 and S1 in the fraction of peak-1 polysaccharide. Hemagglutination-inhibition (HI) antibody to type 1 hemagglutinin of HG (trypsin-sensitive hemagglutinin) was detected in chickens immunized with this fraction from strain 221 but not with that from strain S1. Type specificity between both strains was also found in this fraction by agar-gel precipitation (AGP) test. On the other hand, the toxic fraction of peak-2 polysaccharide, which caused hydropericardium in chickens, had a lower molecular weight than did that of peak-1 polysaccharide. It did not give HI antibody in chickens. Common antigenicity between strains 221 and S1 was found in the peak-2 polysaccharide by AGP test.
Three Beaudette strains of infectious bronchitis virus (IBV) [two chicken-embryo trachea-culture-adapted (E71CET10 and E71CEK10CET30) and one embryo-adapted (E72)] were propagated in 10-day-old embryonated chicken eggs (CE) to investigate growth and lethality patterns. The E72 and E71CEK10CET30 viruses were similar in growth pattern as to logarithmic phase and maximum virus production, but 95% of the CE mortality with E72 virus occurred between 20 and 32 hours whereas with E71CEK10CET30 60% mortality occurred between 36 and 84 hours. The yield of the E71CET10 virus was minimum, with little lethality.
Sensitivity of the Beaudette strain of infectious bronchitis virus (IBV) to non-antibody inhibitors in neutralization tests depended on the passage history of the virus. The chick embryo kidney cell-adapted (E71 CEK11) virus was the most sensitive, but after one chick embryo (CE) passage (E71 CEK11 E1), this virus showed reversion to the sensitivity of the parent virus (E71). IBV inhibitors in chicken serum could be removed by treatment with trypsin but not with phospholipase C.
Hyperuricemia was produced in chickens by artificial infection with nephro-pathogenic infectious bronchitis virus (IBV) and studied. Typical respiratory symptoms were found in all of the chickens after inoculation with the nephropathogenic AM-83 strain of IBV. Sixteen out of 30 chickens died from 4 to 14 days after challenge. The level of uric acid in plasma was very high at the day before death and the values in the majority of chickens was more than about 100mg/dl. The chicken surviving against the IBV challenge had hyperuricemia for a longer time than the dead chickens. A few chickens had hyperuricemia for only one day with very low levels of uric acid.Chickens in contact with the chickens challenged with AM-83 strain of IBV also died of hyperuricemia, but some of them were resistent to the challenge.We demonstrated that the hyperuricemia in the chickens infected with IBV was divided into the 4 grades of uncertain, mild, moderate and severe.
