STUDIES ON THE HEMATOXIC EFFECT OF NEWCASTLE DISEASE VIRUS UPON THE GUINEA PIG

Abstract

It is widely known that the Newcastle Disease Virus (NDV) modifies some species of the avian and mammalian red blood cells and produces some several new antigenicities on the red blood cells (r. b. c.).
On the other hand, several cases of hemolytic anemia caused by NDV had been reported by Moolten et al., Negative results were, however, described by Morgan, Wright et al., who attempted to isolate the same virus from the patients of acquired hemolytic anemia.
It may be interesting to examine following problems; 1, Is the modification of red blood cells caused in vivo by a viremia of NDV? 2, From an immunological or hematological standpoint, what responses will follow if the modification of r. b. c. with NDV is exhibited in vivo? For the purpose of studying these, a number of guinea pigs were injected with purified NDV intracardially.
The viremia was continued for about 50 hours when NDV was injected intracardially. The r. b. c. of the guinea pigs in which the viremia was continued were highly phagocytized by tissue-cultured spleen macrophages, e.g., the phagocytic indexes 3 hours after the injection of NDV were 42 and 51, then those decreased and came to the normal range after 58 to 88 hours. This fact indicates that the modification of the r. b. c. by the viruses may be exhibited in vivo during the viremia. NDV-hemagglutination inhibition antibodies were markedly produced and kept in high titer even 60 days after; however, the NDV-modified cell agglutinins which were also markedly produced had decreased more rapidly and came to the normal range at that time.
Positive antiglobulin tests were obtained from 7 guinea pigs out of 18 into which were injected NDV. Also positive results were obtained from 6 out of 16 in the trypsin tset at 37C. The 2 tests became negative 19 or 23 days after the last injections. Cold trypsin test were performed on 10 guinea pigs of which 6 showed the positive agglutinations. Those agglutinations continued for 23 days. False positive trypsin tests as seen in the human sera were not seen in the 20 normal and 4 guinea pigs immunized with rabbit serum. Those sera did not contain the cold hemagglutinins. So, it may be evident that the positive trypsin tests have a pathological means.
The r. b. c. of the guinea pigs from which the positive antiglobulin tests were obtained were moderately phagocytized by the spleen macrophages. This fact suggests that the antibodies detected through the antiglobulin test may have an opsonized capacity as the autoantibody in the sera of the patients suffering from acquired hemolytic anemia.
The moderate anemia was seen temporarily at the stage of the viremia in the 3 guinea pigs out of 4 and in a slight degree in one of the 4 guinea pigs at the stage at which the positive antiglobulin tests were obtained.