Electron microscopic localization of virions in developing teeth of young hamsters infected with minute virus of mice.

Virus particles were detected within the nuclei and cytoplasm of odontogenic cells in the developing teeth of young hamsters infected with a small DNA virus (MVM). Disturbances of normal cytodifferentiation and organogenesis occurred as a result of viral multiplication. Virions were also observed in dense lysosome-like bodies of activated monocytes within the periodontal ligament and adjacent connective tissues.

Teratogenic effects of ribavirin on hamster and rat embryos.

Ribavirin, a synthetic nucleoside with marked antiviral activity, induced developmental malformations when administered to pregnant hamsters by oral, intraperitoneal or intravenous routes. Abnormalities of the limbs, eyes and brain were the most common defects found in the hamster. Higher doses (about 10 x) were required to induce anomalies in rat embryos and the malformations were generally restricted to the head region.

Congenital anomalies induced in hamster embryos with ribavirin.

Ribavirin, when given to pregnant hamsters in relatively small single doses, induces congenital anomalies of limbs, ribs, eyes, and central nervous system, as well as fetal deaths. On the basis of these findings, caution should be used in giving ribavrin to women of child-bearing age.

Exencephaly in fetal hamsters following exposure to hyperthermia.

Exposure of pregnant hamsters on gestation day 8 to 40 or 41 degrees C for one hour caused an increased rate of resorption and a high frequency of exencephaly and encephalocele. Longer exposures often killed pregnant females. Hamsters that had fetuses with abnormalities usually experienced body temperature elevations of 3-4 degrees C above normal (37 degrees C).

Oxygen tension and the selective tropism of K-virus for mouse pulmonary endothelium.

This study focused on the unique nature of K-virus pneumonitis in suckling mice. This process, rather than being a conventional pneumonitis, is characterized by viral replication and cytopathic effects restricted exclusively to pulmonary endothelium. The selective viral attack on this air-blood interface suggests that K-virus is an endotheliotrope that requires a richly oxygenated intracellular milieu for replication.

Carrier determined tolerance with various subclasses of murine myeloma IgG.

Groups of BALB/c mice were treated with various conjugates of 2,4 dinitrophenyl (DNP) and BALB/c myeloma proteins belonging to the four subclasses of IgG (IgG1, IgG2, IgG2b, IgG3). Immediately therafter, they were challenged with DNP-keyhole limpet hemocyanin in complete Freund's adjuvant and antibody to the hapten was measured by direct and indirect hemolytic plaque assay. The results show that all subclasses of IgG are effective as tolerance-inducing carriers.

Hemorrhagic necrosis of the central nervous system. A spontaneous disease of fetal hamsters.

During studies of transplacental virus infections in random bred hamsters purchased with timed pregnancies from three commercial dealers, spontaneous hemorrhagic necrosis of the central nervous system was seen in fetuses harvested near term. Ninety-seven pregnant hamsters from three colonies were examined during a 6-month period; this condition was seen in 25 of 41, 19 of 36, and five of 20 litters. Hamsters from another commercial colony were received, housed, and fed under the same conditions, but remained free of the disease.

Induction of congenital hydrocephalus in hamsters with attenuated and natural strains of mumps virus.

The abilities of a low-passage strain and of a live, attenuated vaccine strain of mumps virus to induce congenital hydrocephalus in hamsters were tested by intraamniotic inoculation on the 10th day of pregnancy. Examination of term fetuses and neonates, with cytoplasmic inclusions, cytopathic effects, and specific immunofluorescence used as indicators, demonstrated an oronasal portal of entry for both strains. The vaccine strain appeared to be more pathogenic; it spread primarily into the respiratory tract and hence to the central nervous system.

Encephalitis in suckling rats induced with rat cytomegalovirus.

Encephalitis has been induced in suckling rats by intracerebral inoculation of rat cytomegalovirus. This agent has been carried through five animal passages without changes in virulence. Principal sites of viral attack were the meninges and ependyma with limited parenchymal invasion from these sites.

Experimental adenovirus infection of the mouse adrenal gland. II. Electron microscopic observations.

A strain of mouse adenovirus, found to have a striking tropism for the weanling mouse adrenal gland, enabled electron microscopic examination of adrenals in various stages of infection. Nucleolar hypertrophy and the successive formation of three types of inclusion bodies in association with nucleoli preceded virion production. Angular crystals of virions formed in the affected nuclei.