A Generalized Infection of Newborn Hamsters with Type 2 Adenovirus

Abstract

Discussion and Gcneval Conclusions

These results indicate that adenovirus type 2 infection may be established in the newborn Syrian hamster as a result of parenteral injection of a relatively high virus dose. Virus was rapidly absorbed from the injection site and disseminated via the circulation and detected in blood. liver, and kidney before a single virus replication cycle had occurred. Prefelential distribution to these organ is consistent with the magnitude of their blood supply (8).

Replication had occurred in liver and kidney by 48 hr and the infectivity of these organs continued to increase through 144 hr, generally parallel with infectivity of serum. Since gross pathological changes and virus particles were found in these organs only and viral inclusions were found in liver cells only it is concluded that the major sites of viral replication were in cells of these organs. The viremia which occurred after replication had been established in these organs probably was a reflection of this however, viral replication in vascular endothelium or cellular elements of the blood may have occurred.

Infectivity of tissues of lung, liver, and heart appeared later and was of lower titer; this could have reflected viremia or intravascular virus production. Low infectivity in these organs corresponded well with absence both of pathologic changes and intracellular viral particles by EM. Whether or not infection of these organs was established could thus not be ascertained.

Pereira and Kelly (4) reported that rabbits inoculated with adenovirus type 5 developed complement fixing CF and neutralization antibody but failed to develop signs of infection. Virologic studies of homogenates of spleen were generally negative for infectious virus, whereas splenic cells when explanted into monolayer culture were observed to produce infectious virus in the absence of cytopathogenic changes after a 2-week latent period. Jennings and Betts (5) reported that adenoviruses type 1, 2, 4, and 6 caused silent pneumonitis in germ-free piglets when given intratracheally. Likewise, adenovirus types 2, 3, 4, and 7 apparently infected dogs, asymptomatically (6). Later, Pereira (7) and others presented evidence for type 5 adenoviral infection resulting in necrotizing hepatitis, as a part of a generalized infection of newborn Syrian hamsters.

Whereas adenoviruses of other types paraticularly 12 and 18, are oncogenic for new born hamsters (9-11) and to a limited extent other rodents (12) these viruses do not cause productive infection in these animals.

The infection with a type 2 virus described here thus resembles the infection of newborn hamsters with type 5 as described by Pereira Limited comparison of the P-3-66 virus with prototype 2 virus gave evidence that the prototype also is infective for the newborn hamster without evidence of progressive infection and without mortality. Likewise, the P-3-66 virus also produced silent infection in newborn Swiss mice. Neither virus infected adult hamsters.