A Virus Pneumonia of Syrian Hamsters. ∗

In the course of attempts to infect Syrian hamsters (Cricetus auratus) 2 to 4 months old, with influenza A, virus strain W. S., 1 another filterable agent capable of producing a fatal pneumonia in these animals was found. One hamster was inoculated intranasally with mouse-passage influenzal virus (W.S.) and developed slight nasal symptoms. This animal was sacrificed after 8 days and suspensions of lung and turbinate were passed to a second hamster which had large plum-colored pneumonic areas in its lungs when killed at 6 days. Subsequently suspensions of lung and turbinate have been carried through 17 serial intranasal passages in hamsters with the production of pneumonia in each passage except the first and third. The suspensions at each hamster-passage when inoculated intranasally into mice produced a pneumonia which was usually fatal within 6 to 9 days. Attempts to produce a similar pneumonia in hamsters with several other mouse-passage strains of influenzal virus were unsuccessful. We were also unable to repeat the original experiment starting with another mouse-passage of the strain W.S.

Cultures of lung and turbinate-suspensions on the ordinary bacteriological media gave either no growth or only a few colonies of various kinds of bacteria. A Berkefeld V filtrate of a suspension was infectious for hamsters, but not for mice. The agent failed to pass a Seitz filter.

Signs of infection in the hamster were variable, but usually 2 to 6 days following nasal inoculation the animal sniffed or sneezed and rubbed its nose. Then rhonchi, ruffled fur, dyspnea, and weakness were noted. Death occurred in 6 to 15 days, sometimes preceded by a terminal bloody nasal discharge. The only change in temperature was a terminal fall.

The lungs of dead animals were moist, plum-colored and completely consolidated.