Baby Mice Research Articles

Multiplication in and transmission by Aedes aegypti of vesicular stomatitis virus

The multiplication of vesicular stomatitis virus (VSV) in Aedes aegypti mosquitoes is about 4.5 logs 7 days after intrathoracic injection of 25 PFU of the “Indiana” strain and about 3.5 logs after injection of 2.5 PFU of the “New Jersey” strain. Higher doses cause no increase of multiplication. The multiplication in eight different organs follows a similar pattern. The concentration is highest 2–3 days after injection and shows a lower peak after 6–8 days before it drops. The specific virus concentration per microgram of wet organ is highest in the thoracic and abdominal ganglion, and after 20 days in the salivary glands. “Indiana” but not “New Jersey” could easily be expelled from the lumen of the intestine by slight pressure resulting in titers up to 3 logs PFU/mosquito. Therefore expelling of virus may take place during oviposition. Electron microscopic investigations of the insect's tissues reveal VSV particles in the salivary glands, intestine, thoracic and abdominal ganglion, and midgut, but not in the cerebrum and both diverticuli in spite of high virus titers present. The particles occur nearly always in groups and within cisterns and tubuli of the endoplasmic reticulum. They are located in all three acini towards the periphery of the salivary glands or close to the internal duct. In the intestine they are found close to the wall neighboring the coelom. Transmission to baby mice by mosquitoes after intrathoracic injection takes place very regularly commencing from the 2nd–4th day until at least 20 days. Transmission efficiency is independent of the titers in the mosquitoes within a range of 2.18–5.48 logs for “Indiana” and within 1.16–2.89 logs for “New Jersey.” Indiana virus was transmitted by 45% of the mosquito lots (5 mosquitoes/lot) to about 11% of baby mice. New Jersey virus was transmitted by 20% of the mosquito lots to only 5.2% of baby mice. After 15 days incubation Indiana virus was found in 31% of the 45% transmitting mosquito lots with titers between 1.8 and 3.7 logs PFU 5 mosquitoes; New Jersey virus was detected in 8.3% of the 20% transmitting mosquito lots with titers of 0.5 and 0.7 logs PFU 5 mosquitoes.

Susceptibility of the Marmoset, Saguinus geoffroyi Pucheran, to Intraperitoneal and Oral Infections with Besnoitia (Protozoa: Toxoplasmea)

Cystic and proliferative stages of two strains of Besnoitia darlingi (Brumpt, 1913) and a strain of B. jellisoni Frenkel, 1955 were highly pathogenic for marmosets, Saguinus geoffroyi Pucheran, when administered by either the intraperitoneal or oral route. The clinical picture of disease was similar for both routes of administration and resembled the acute form of the disease as seen in mice. There was a significant correlation between numbers of parasites in intraperitoneal inocula and the day of death. In general, death after oral administration occurred somewhat later than after intraperitoneal inoculation. But cystic B. darlingi killed more quickly than proliferative forms when both were given orally; however, individual variation in monkey hosts may have been as important as strain or stage of the parasite, with regard to time of death. Using relatively large numbers of organisms, all of 22 intraperitoneal infections and 21 of 26 oral infections proved fatal. Parasitemia was detectable at the time of death following both routes of inoculation. When the numbers of organisms were too small to establish a fatal infection they also failed to immunize. Protective immunity, detectable by subsequent intraperitoneal challenge, was established in two monkeys receiving large numbers of parasites by mouth. A monkey which became demonstrably immune to B. jellisoni (PN-3) was shown by heterologous challenge to be still susceptible to B. darlingi (D-3). Mouse-adapted Besnoitia darlingi (= B. panamensis) of lizard origin was reported to be experimentally pathogenic for Geoffroy's marmoset (Schneider, 1965). The disease in this animal was described as an acute, rapidly fatal infection accompanied by considerable ascitic fluid in which numerous proliferative forms of the parasite were found. The disease in the marmoset, in fact, very much resembled the disease in the mouse. The present paper presents the results of additional studies of marmoset besnoitiosis in which experimental infections were induced with either cystic or proliferative stages of three strains of Besnoitia by the intraperitoneal or oral route. MATERIALS AND METHODS Geoffroy's marmoset (Saguinus geoffroyi Pucheran) abounds in low forest and secondary growth throughout most of Panama. The monkeys could be obtained from street vendors during certain times of the year. If they survived in captivity the first few days, they did well on a diet of fruits supplemented with meat (grasshoppers or baby mice). They would sometimes accept adult mice, eating out the brains, muscles and viscera and throwing away the skin. Almost 100% had microfilariae in the blood and many were infected with a trypanosome. Received for publication 28 November 1967. * Present address: Parke, Davis & Company, 2800 Plymouth Road, Ann Arbor, Michigan 48106. A total of 53 marmosets were used in the present series of experiments. Administration was by the intraperitoneal or oral route. Intraperitoneal inoculations were made in the area of the right groin with a 21-gauge needle. Orally, parasites were delivered directly into the mouth of the hand-held animal from a small syringe without needle; if given slowly, permitting time to swallow, all monkeys readily accepted the dose once it had been tasted. To avoid trauma, stomach intubation was not used, and anesthetics were avoided as risky and

Ultrasound in adult rodents.

PRODUCTION of ultrasound by baby rodents has been reported by Zippelius and Schleidt1 in Apodemus f. flavicollis Melchior, Mus musculus domesticus Rutty, and Mictrotus a. arvalis Pallas, and by Noirot2,3 in baby mice, Clethrionomys glareolus Schr., Mesocricetus auratus Waterhouse and albino rats. I have now confirmed this phenomenon for the young of Clethrionomys, Mesocricetus and laboratory rats and mice, and extended it to the young of Acomys caharinus (Desmarest), Meriones shawi Rozet, M. unguiculatus Milne-Edwards, a species of Gerbillus, Apodemus sylvaticus (L.), Mus minutoides and a species of Thamnomys.

Characteristics of bovine mammillitis virus.

SUMMARY: A virus isolated from cattle in Scotland does not seem to have been described previously as existing in Europe. The virus has been provisionally designated bovine mammillitis virus (BMV). It grows in tissue cultures, particularly of bovine origin, giving rise to large multinucleate cells which have type A inclusions in many of their nuclei. Baby mice injected with it develop skin lesions, but only a limited number of passages can be made. The BMV particle has a nucleocapsid of about 80 mμ diameter which, in complete particles, is surrounded by a loose envelope. The virus is sensitive to ether and chloroform, and contains DNA with a base composition of 64% G+C and a band-width molecular weight of 34×106. BMV shows antigenic similarity, in neutralization tests and double-diffusion tests in agar, to the group II viruses (prototype Allerton) of lumpy skin disease (Alexander, Plowright & Haig, 1957). All these features place it in the family of the herpesviruses.

Antibody response and antigenic difference between high and low oncogenic variants of SE polyoma virus.

Production and development of antibodies in rabbits, chickens, baby and adult mice and hamsters inoculated with three polyoma virus variants, differing in their oncogenicity, was studied by neutralization, HI or cross absorption tests.

Studies on the growth and transmission of two viruses of the bunyamwera group in Aedes aegypti Linn

Experiments are reported concerning the infection of Aedes (Stegomyia) aegypti Linn. with two arboviruses belonging to the Bunyamwera group—Ukauwa and Ilesha viruses. Aedes aegypti was readily infected with Ukauwa virus by feeding upon sick infant mice, feeding upon infected blood through a mouse-skin membrane, or by inoculation of virus into the insect, and high virus titres were attained. Attempts to infect mosquitoes with Ilesha virus by ingestion failed, but this failure may have been due to the relatively low virus titres employed. Mosquitoes were infected with this virus by inoculation. Aedes aegypti infected with both viruses were able to transmit infection to baby mice, although their ability to transmit Ukauwa was considerably greater than for Ilesha virus. It was concluded that Aedes aegypti may under certain circumstances function as an efficient vector of Ukauwa virus, and, to a lesser extent of Ilesha virus.

Thymus and the Production of Antibody-plaque-forming Cells

ALTHOUGH the thymus itself does not play an active part in immune responses1, its presence is essential for the normal development of immunological faculties. Neonatal thymectomy in many species considerably impairs the capacity of an animal to produce some types of immune responses2. Thymectomy in adult life has no immediate effect but, after a period of 6–9 months, reduces the capacity to react to a newly encountered antigen3. The possible mechanisms by which the thymus exerts its influence on the immunological system have been discussed elsewhere4, and it has been concluded that the immunological defects encountered after thymectomy are primary and not secondary to infection or auto-immunity5. Evidence is presented here to show that thymectomy practically inhibits the development of the capacity to produce antibody-plaque-forming cells following the injection of sheep erythrocytes. This impairment is evident in clinically healthy suckling baby mice thymectomized at birth.

Contribution of the pentose cycle to glucose metabolism in muscle

Glucose-2-C 14 has been incubated with abdominal muscle, diaphragm, and slices of heart from baby and adult mice. Glucose from glycogen and ribose from nucleotides have been degraded. From the C 14-distribution in the glucose, the pentose cycle contribution to over-all glucose metabolism in abdominal muscle and diaphragm could not definitely be established, but it does not exceed 2%; in heart it appears to be somewhat higher. Distributions of C 14 in glucose from glycogen and ribose are in accord with incorporation of C 14 via the oxidative and nonoxidative portions of the cycle. While incorporation via the oxidative portion can be attributed to synthesis, incorporation via the nonoxidative portion may occur via exchange reactions rather than synthesis.

VENEZUELAN EQUINE ENCEPHALITIS VIRUS IN VERACRUZ, MEXICO, AND THE USE OF HAMSTERS AS SENTINELS.

Venezuelan equine encephalitis virus was recovered in the state of Veracruz, Mexico, during July and August 1963 from young, weaned hamters, and from baby mice used as sentinel animals, and from Culex mosquitoes. Hamsters of 5 to 10 weeks of age became infected in nature and were nearly as susceptible as suckling mice to subcutaneous inoculation of VEE virus.

Tacaribe Virus, a New Agent Isolated from Artibeus Bats and Mosquitoes in Trinidad, West Indies

Summary Isolation of a new entity, Tacaribe virus, from Artibeus bats and from mosquitoes, in Trinidad, is described. The agent is pathogenic for baby and adult mice and is inactivated by incubation with sodium desoxycholate. It is proposed for inclusion in the group of arthropod-borne viruses.

Isolierung eines Virus aus der Virus-Diarrhöe — dem Mucosal disease-Komplex

The isolation of a virus from a cow with mucosal disease is described. The character of the virus and its possible relationship to other viruses is discussed. It is concluded that the virus is related to the para-influenza group of viruses although it is pathogenic for baby mice.

Studies on mosquito-borne viruses in their vectors: I. The normal fine structure of the midgut epithelium of the adult female Aedes aegypti (L.) and the functional significance of its modification following a blood meal

1. 1) The following organelles and components of the normal fine structure of the midgut cells of adult female Aedes aegypti, as observed in sectioned material studied by electron microscopy, are discussed and illustrated by electron micrographs: the microvilli of the luminal surface, and septa invaginated from the basal cell membrane; the intercellular boundary; a basement membrane and associated tracheoles, muscles and connective tissue; nucleus and nucleolus; Golgi complex or dictyosomes; endoplasmic reticulum; ribonucleoprotein granules of the cytoplasmic matrix; various vesicles, and vacuoles. 2. 2) In starved and sugar-fed mosquitoes, or mosquitoes given water only, the granular endoplasmic reticulum appears, in sections, in the perinuclear zone as distinctive whorls which, however, following a blood meal and during its digestion, unfold to become a complex system ramifying widely throughout the cell cytoplasm. Reversion to whorls takes place on completion of blood digestion and a subsequent diet of sugar fails to stimulate the whorls to unfold. Whorls, and their distension during blood digestion, were also seen in females of Aedes togoi. 3. 3) Some emphasis is given to the possible role of this reversible whorl formation in the segregation and transportation, when unfolded, of proteolytic enzymes for the digestion of the blood meal in the gut lumen. Cytochemical studies by light microscopy confirm the morphological, and suggest some support for this functional, interpretation of these whorls. But, no completely conclusive explanation of function is yet practicable; possible alternatives are considered. 4. 4) Immediately (within at most half-an-hour) after ingesting blood, a finely granular material, which is to form the peritrophic membrane, appears in the gut lumen between and beyond the tips of the microvilli, apparently secreted from their surfaces. Secretion appears to cease about the 15th hour, or earlier, by which time the membrane is a discrete, finely granular, compacted layer on the surface of the well-digested blood. 5. 5) These electron microscopy studies reveal rapid and elaborate responses by the midgut cells to the presence in the gut of a blood meal ingested by normal feeding on an infant mouse. The fate of virus in mosquitoes infected through a membrane with artificial food mixtures — which are only partially of blood — may be, it is suggested, atypical and inadmissible for the interpretation of virus-vector relationship in mosquitoes infected naturally by engorging from a viraemic host. 6. 6) All intracellular structures and profiles of midgut cells described and illustrated, and changes in them associated with natural blood meals, were seen in Ae. aegypti whether fed on healthy baby mice, or infected with Semliki Forest virus by engorgement from viraemic mice. 7. 7) The paper provides a foundation of normal intracellular structure to be seen in mosquito midgut cells by electron microscopy against which the abnormal in mosquitoes infected with viruses, or other pathogens, may be sought. It also indicates opportunities for the further elucidation of cell function by studies correlating intracellular morphology and its transformations, as observed by electron microscopy, with biochemical, physiological and other experimental analyses.

On the Peripheral Blood Picture and the Bone Marrow Picture of Mice inoculated with Varicella Virus.

Inoculating the pure line baby mice's brain with varicella virus, the author studied their peripheral blood pictures and bone marrow pictures. The results of the experiments were as follows. (1)In the peripheral blood, there was no change in the number of erythrocytes in the peroid of the attack of the disease but hemogrobins decreased a little in quantity, the total number of leucocytes decreased, lymphocytes and neutrophil cells decreased in the absolute value, neutrophil cells shifted toward the left of the nuclei and eosinophil cells decreased or vanished. Monocytes cells increased from the latter period of the attack of the disease till the period of the recovery. Plasma cells did not change themselves and reticulum cells appeared in a few numbers. (2)In the bone marrow pictures, the number of nucleated cells decreased remarkably as well as erythroblast cells and neutrophil cells in the period of the attack of the disease. No. changes were observed in the eosinophil cells. Lymphosytes increased in the period of incubation. The increase in number of monocytes, plasma cells and reticulum cells was observed. Both erythroblast cells and leucocytes showing the nuclear fission pictures increased.

On the Peripheral Blood Picture and the Bone Marrow Picture of Mice inoculated with the Canine Distemper Virus,

The relations between the distemper and the measles have been discussed for years and it is said that the fixed germ of the distemper and that germ of the measles have the common antisubstance. Inoculating the pure line baby mice's brain with the canine distemper virus, the author studied their peripheral blood picturis and bone marrow pictures, comparing those of the mice which caught the measles. (1)In the peripheral blood, in the period of the attack of the disease, a slight decrease in number of erythrocytes and that in quantity of hemogrobins were observed. The total number of leucocytes, lymphosytes, and neutrophil cells decreased and they shifted toward the left of the nuclei. The other cells showed a tendency to increase. (2)In the bone marrow pictures, the number of nucleated cells decreased and at the same time erythroblast cells and neutrophil cells decreased. Lymphocytes die not change clearly themselves and all the other cells showed a tendency to increase. (3)Comparing the blood pictures and the bone marrow pictures of the mice inoculated with the canine distemper virus with those that caught the measles, the total number of leucocytes and the number of nucleated cells in the bone marrow decreased in the former, but increased in the latter. The other changes through the course were almost the same.

A MUTANT OF HERPES SIMPLEX VIRUS POSSESSING AN ATTENUATED PATHOGENICITY FOR BABY MICE OBTAINED BY EGG PASSAGE OF A NEWLY ISOLATED STRAIN

It has been attempted in this laboratory for the past years to isolate and passage herpes simplex virus by the chorioallantoic inoculation of embryonated eggs and pursue the changes in pathogenicities for various host animals occurring during the course of the passage. Among the pathogenicities examined were included those for baby mice intracerebrally or intraperitoneally inoculated, since Kilbourne and Horsfall (1951) stated that one-day old mice were equally susceptible to herpes virus inoculated by these two routes. A strain designated SK was studied most extensively.A fact came to light thereby that the SK strain after passaged through eggs about 50 times was hardly lethal to baby mice when given by the intraperitoneal route, whereas the classical HF strain experiencing more than 450 egg passages still possessed a high infectivity to baby mice even by the peripheral inoculation. This paradoxical result stimulated a quantitative analysis of the infectivities to baby mice of SK strain in comparison with HF strain, and it was eventually disclosed that a mutant had appeared incidentally in an early egg passage of SK strain, which subsequently had replaced the parent type virus after several more passages. Details of those experiments are reported in the present communication.

The transmission of Semliki Forest virus by Aedes aegypti L.

1. 1) Biological transmission of SFV by Ae. aegypti between baby mice was obtained daily from the 2nd to 15th day after the mosquito's infecting feed, and occasionally thereafter until at least the 46th day. Probing only, or engorgement, of a single mosquito was sufficient on some occasions to effect transmission. 2. 2) Mechanical transmission was obtained by interrupting mosquitoes during an infecting feed, and also by re-feeding after 24 hours. Mechanical transmission possibly continues for several days under certain conditions.

Guaroa virus, a new agent isolated in Colombia, South America.

Summary A virus was isolated from the blood of 6 out of 119 persons living in Guaroa, eastern Columbia. The locality is a recent settement situated at the edge of a natural savannah in the vicinity of a stretch of tropical rain forest. There is evidence that the agent isolated was the same in five of these persons. Serological studies showed that this agent was not identical with any of the 36 different anthropod-borne viruses with which it was compared, nor, in view of the known cross relationships among members of a group, could any evidence be found indicating that the virus belongs in groups A, B, or C. Our serological studies indicate that the virus is not related to Anopheles A, Anopheles B, and Wyeomyia. The conclusion derived from the immunological studies indicated that this was a new agent, to which the name Guaroa was given. A distant relationship was found between Guaroa and California encephalitis virus; this very slight overlap was detected by HI, but not by CF, and in one direction only. Although California immune sera inhibited a Guaroa antigen, Guaroa sera failed to inhibit a California antigen. Additional studies are clearly indicated to elucidate this crossing. Guaroa virus is pathogenic for white mice, regardless of age, when inoculated by the intracerebral route. When the subcutaneous route is used, it produces fatal infections in baby mice, but not in adults. Two rhesus monkeys inoculated subcutaneously and intradermally with the human sera from which the viruses were isolated, showed viremia and immunological conversion, but none developed fever or any clinical disease. Guaroa virus was isolated from persons who, at the time of the bleeding, did not complain of being sick. Four of these individuals apparently continued to enjoy good health during the month following the isolation of the virus. One person had a mild febrile illness lasting two days which started on the second day after the bleeding. It was not possible to continue the study of the sixth individual. A large proportion of residents of Guaroa was found to have neutralizing antibodies for Guaroa virus, which indicates that the agent was very prevalent there.

On the Image of Blood and Bone Marrow of Mice Attacked by Japanese Encephalitis Virus

Inoculating baby mice's brain with Japanese Encephalitis virus, the author studied the image of their blood and bone marrow and obtained the following results. 1. In the image of peripheral blood, leucocytes increased in large numbers and they moved towards the left of nuclei, lymphocytes decreased in number, eosinophil cells decreased or vanished away, and plasma cells and reticuloendothelial cells increased. 2. In the image of bone marrow, nucleated cells in bone marrow, neutrophil cells and erythroblasts cells increased abundantly in the incubation period as well as at the beginning of the attack of the disease and decreased after the middle period of the disease. 3. These results are much the same to those of Japanese Encephalitis patients.

Infection of the one-day old fertile hen's egg with rabies virus. III. Some observations on high egg passage (HEP) strains.

The previous reports from this laboratory (Yoshino et al., 1956 a, 1956 b) indicated that both mouse passaged CVS and 7-day egg passaged Flury strains of rabies virus could infect the 1-day egg resulting in high viral concentrations in the embryo which were comparable to those usually reached in the infected mouse brain, and that these strains after adapted to the 1-day egg by serial passage could be satisfactorily titrated in 1-day eggs. This new titration method was especially of use for rabies virus, since the 1-day egg LD titration could be performed with more ease and shorter time than the conventional mouse infectivity test which had been the only method of titration available for this virus.Meanwhile, Koprowski et al. (1954) found that 7-day egg passage of the Flury strain eventually produced a high egg passage (HEP) line which was unable to kill adult mice. The HEP Flury virus could be titrated by inoculation into baby mice, but there has been no other titration method for this particular virus routinely applicable in laboratory. Yet the use of baby mice has the disadvantage of occasional appearance of cannibalism, and therefore attempts were made here to adapt the HEP Flury virus to the 1-day egg with the expectation that it would become able to be titrated in 1-day eggs. When this attempt was started, however, a surprising fact was discovered that the HEP Flury virus, without any preliminary passage in 1-day eggs, was already as highly pathogenic to the 1-day egg as if it had received many previous 1-day egg passages. In the meantime, Takamatsu (1956) also passed Nishigahara strain in 7-day eggs for several years and reproduced the results of Koprowski et al. (1954), providing another HEP rabies virus. On examination of the pathogenicity for the 1-day egg of the HEP Nishigahara strain, we again found the same fact as revealed with the HEP Flury virus, i. e. it possessed high pathogenicity for the 1-day egg before any 1-day egg passages were tried.Owing to this unexpectedly high pathogenicity for the 1-day egg of these HEP rabies viruses, they could easily be titrated in 1-day eggs, and as a consequence a way was opened for easy access to the biological properties. Detailed experi ments further demonstrated that these two HEP rabies viruses were not identical with each other in certain respects, and an analysis of the results obtained seemed to give a clue to solve the question of why and how the two different HEP viruses came to appearance, as will be stated in this communication.

Infection of the one-day old fertile hen's egg with rabies virus. IV. A quantitative analysis of infective units for mice (MIU) and for one-day eggs (OIU).

In our previous work (Yoshino et al., 1956 a), mouse fixed CVS as well as earlier 7-day egg passage of Flury strain showed nearly equal infective titers in both 1-day egg ID and mouse LD tests, but serial passage in 1-day eggs resulted in an increase approximately ten-foldly in the ratio of 1-day egg 1D to mouse LD titers. At first, it was expected that this difference between the two titers would become increasingly more pronounced as passages were repeated in 1-day eggs until finally the mouse infectivity would be lost. However, quite contrary to this expectation, the 1-day egg passage strains, COP and FOP, even after many passages through 1-day eggs did not alter this ratio and sustained as much infectivity for adult mice as did respective mother strains, CVS and Flury.Then became important the question of whether or not one mouse LD (MIU) of the 1-day egg-adapted lines was equivalent to that of their mother viruses in terms of viral particle number. If one mouse LD of a mother strain represented N particles while that of its 1-day egg-adapted line corresponded to pN particles, a direct comparison of viral yields between these two viruses might be possible only after correction of the latter titer by the factor of p.As was previously demonstrated (Yoshino et at., 1956 a), the peak viral concentration in the embryo obtained by the infection of 1-day eggs was as high as was reached in the mouse brain when both titers were expressed in terms of MIUs and therefore it was thought possible that more detailed investigations on the quantitative significance of MIU would revise our previous view concerning the viral yield in such young embryos. Approaches to this problem were quite difficult, because we had to resort only to indirect measurements of virus particles such as animal infectivity tests. However, the use of baby mice, which were found to be more susceptible than adult mice, and neutralization tests with a rabbit antiserum seemed to cast light on the solution of this problem. In order to avoid complexity, studies were confined to the relation between the mousefixed CVS and its 1-day egg passage line COP as a representative combination.The results obtained appeared to point to an equal equivalence of MIU between these two viruses. It was also noticed that, in the ordinary titration employing adult mice, much of active virus was missed by detection even in the case of mouse-fixed strains, while the 1-day egg could be esteemed as one of the most sensitive hosts to detect active virus, at least for certain lines of rabies virus.