Adaptation of the “New Guinea B” Strain of Dengue Virus to Suckling and to Adult Swiss Mice

Abstract

Adaptation of the Hawaiian strain of dengue virus to growth in the brain of young adult Swiss mice was a gradual process (1). When serial transfers were made with 10 per cent mouse brain suspensions serving as inocula, it required 15 passages before all of the mice became paralyzed. Once paralysis and death occurred regularly, the titer of the virus could be calculated, and after many further passages it increased from an initial value of about 102 to about 10' LD50 per 0.03 gram of brain tissue. Subsequently, following a suggestion by Dr. Gordon Meiklejohn, the mouse-adapted Hawaiian strain was propagated in 3 to 4 day old mice, and this yielded 100-1,000 times higher infectious titers. Furthermore, infected baby mouse brain was found to be a good source of complement-fixing antigen (2). From 1944 to 1946, Sabin and Schlesinger attempted in a number of ways to adapt to mice 3 other strains of dengue virus, i.e. the New Guinea â€oeB―, â€oeC― and â€oeD― strains which were recognized as being immunologically distinct from the Hawaiian type (see (3)). Partial success was obtained when the viruses were inoculated intracerebrally into mice of the dba strain. It was also noted that primary â€oetakes―, i.e. evidence of infection in the form of weakness or paralysis of the extremities, were more apt to follow inoculation of dilute than of undiluted or concentrated virus from human sources (1). Stimulated by the usefulness of the suckling mouse in enhancing the in fectivity of the Hawaiian strain, we decided to attempt reactivation of a series in which the New Guinea â€oeB― strain had been carried through eight successful passages in dba mice. It has been possible to adapt this strain to Swiss baby mice. This process of adaptation has been closely analogous to that reported by Meildejohn et al. (4) for the New Guinea â€oeC― and â€oeD― strains. Since these investigators were unable to obtain similar results with the â€oeB― strain, it is one of the purposes of this communication to round out the present status of known types of dengue virus in relation to pathogenicity for mice and to sero logical group relationship. The second purpose is to describe the gradual ac quisition by the virus of pathogenicity for adult Swiss mice as well, a process which by its nature raises several points of general interest in relation to the problem of viral variation in the course of adaptation to new hosts.

Epitope Determinants of a Chimpanzee Dengue Virus Type 4 (DENV-4)-Neutralizing Antibody and Protection against DENV-4 Challenge in Mice and Rhesus Monkeys by Passively Transferred Humanized Antibody

“…The protective efficacy of IgG 5H2 ⌬D was evaluated using a mouse DENV encephalitis model described previously (24,52). Passive transfer of IgG 5H2 ⌬D at a dose of approximately 20 g/mouse afforded 50% protection against challenge with 25 LD 50 of the mouse-neurovirulent DENV-4 strain H241.…”

Genetic determinants of dengue type 4 virus neurovirulence for mice

“…Although dengue virus infections in human do not manifest encephalitis symptoms, several other members of the Flavivirus genus cause acute encephalitis in humans, and there is significant homology (35 to 50%) among the E sequences of dengue viruses and other members of the Flavivirus genus. Although DEN4 from an intermediate mouse brain passage level has not been evaluated for utility as a vaccine, dengue virus type 1 and type 2 mutants selected in this manner were shown to be attenuated for humans (16,24,27). Analysis of amino acid changes in these viruses during serial mouse brain passage might help to identify other sequences that confer attenuation for humans and at the same time contribute to mouse neurovirulence.…”

“…Various strategies have been explored to produce an effective vaccine for prevention of dengue virus infection ever since the dengue virus was isolated more than half a century ago. During early studies, serial intracerebral passage of dengue type 1 or type 2 virus in mice was used to attenuate these viruses for development of candidate strains for inclusion in a vaccine to be used in humans (16,(24)(25)(26)(27). Studies by Hotta showed that the Mochizuki strain (dengue type 1) virus lost its virulence for humans after 17 passages in mouse brain (16).…”

Isolation of Three Strains of Type 1 Dengue Virus from a Local Outbreak of the Disease in Malaya

“…Hotta (1952) achieved mouse adaptation of a strain of dengue-1 virus in 6-7 g. mice but did not observe paralysis until after two blind passages. Meiklejohn appears to have been the first to suggest the use of suckling mice for propagation of dengue viruses (Schlesinger & Frankel, 1952). It is because there have been so few successful isolations of dengue viruses and these with difficulty that the isolations reported here are described in detail.…”

“…They failed to adapt strain 'C' directly to adult mice after nine blind passages. Schlesinger & Frankel (1952) adapted the New Guinea 'B' strain of type 2 virus to suckling mice after four passages in DBA mice and two in suckling Swiss mice. Nineteen further passages in sucklings were necessary to adapt the virus to adult mice.…”