Erskine L. Palmer

Reovirus-like agent as a cause of nosocomial diarrhea in infants

Surveillance for nosocomial diarrhea due to a reovirus-like agent was maintained on the pediatric wards of a large metropolitan hospital in January and February, 1976, during a large community outbreak of that illness. During this period, 30 (27%) of 111 children under surveillance were admitted for dehydration secondary to diarrhea; 21 (70%) of these 30 children had RLA in stool samples obtained at admission. Ten (17%) of the 60 children admitted without diarrhea, hence at risk of acquiring nosocomial RLA infection, contracted the illness. With human RLA as an antigen, no hospital personnel had serologic (complement fixation test) evidence of infection. Early attempts to control the diarrhea at home and in the outpatient department by the use of oral fluid rehydration, isolation of patients with severe symptoms requiring hospitalization, and strict attention by hospital personnel to hand washing between examination of patients may limit nosocomial spread of the disease.

Ultrastructure of infantile gastroenteritis virus

Abstract The virus associated with acute gastroenteritis in young children (infantile gastroenteritis virus (IGV) was examined by negative contrast electron microscopy. The surface of the particle was found to be composed of 32 large morphological units or capsomeres. In the closed shell of the particle they were clustered into a coordinated pattern characteristic of a T = 3 morphology and at low magnification appeared ring shaped. However, at a high magnification they were seen to be angular. Each was composed of separate wedge shaped subunits. There were 180 of these units, each of which was a trimer making a total of 540 structural units on the surface of the particle. The wedge shape of these subunits and their trimer arrangement follows the structure postulated for a T = 9 icosadeltahedron. Thus, on the level of structural units the particle conforms to a T = 9, whereas in the clustering of these units into 32 capsomeres, it conforms to a T = 3 morphology similar to that described for viruses of the orbivirus group.

Protein composition of coronavirus OC 43

Abstract A human coronavirus, strain OC 43, was propagated in suckling mouse brain and purified 5000-fold with, a 90% yield. Purity of the virus was confirmed by electrophoretic, ultracentrifugal, and electron microscopic procedures. Immunodiffusion and immunoelectrophoresis tests revealed one precipitin line with normal mouse brain, three with purified virus, and four with crude virus when tested against anti-pure virus or anti-crude virus animal serums. The association of a host cell antigen with the virion was confirmed by standard HI and CF tests. Polyacrylamide gel electrophoresis of solubilized purified virus revealed a minimum of six polypeptides with apparent molecular weights of 191,000 (No. 1), 104,000 (No. 2), 60,000 (No. 3), 47,000 (No. 4), 30,000 (No. 5), and 15,000 daltons (No. 6). A seventh band was occasionally found in the 165,000-dalton region of the gels. Four polypeptides contained carbohydrate and one contained lipid. Polypeptide No. 5 comprised 26% of the total viral protein and glycopolypeptide No. 3 comprised 23%. Three other components accounted for most of the remaining protein: polypeptide No. 4 (16%), glycopolypeptide No. 6 (14%), and glycolipopolypeptide No. 1 (13%). Glycopolypeptide No. 2 was 8% of the total protein. Bromelin digestion of the viral projections (spikes) removed glycopolypeptides No. 2 and No. 6. Association of the remaining polypeptides with structural components of the virion is only tentatively postulated. The buoyant density in potassium tartrate of the bromelin-treated virus was 1.15 g/cm3 and of the intact OC 43 virion was 1.18 g/cm3. By analytical ultracentrifugation the corrected sedimentation coefficient (s 0 20w) of the OC 43 virion was determined to be 390 ± 16 S, and the apparent molecular weight (MW a ) was calculated to be 112 ± 5 × 106 daltons.

The ultrastructure of disrupted herpesvirus nucleocapsids

Abstract Nucleocapsids prepared by treating herpes simplex or varicella-zoster virions with Nonidet P-40 were found to be degraded by EDTA-trypsin. Initial action of the enzyme appeared to be to degrade the pentameric capsomeres located on the vertices of the icosahedron and thus cause the capsid to flatten and the capsomeres to align in a characteristic radial array. Examination of hexagonal clusterings of capsomeres showed that they were linked by strands approximately 2 nm wide which originated from edges of the hexagonal prisms. A tri-membered arrangement for these intercapsomeric linkages was proposed in which one strand linked adjacent capsomeres and the central capsomere of the cluster.

Studies on the poxvirus cotia

The poxvirus Cotia was studied by electron microscopy and by serological and biochemical analyses. Thin-sectioned preparations of infected Vero cells indicated that Cotia virus morphogenesis was similar to other mammalian poxviruses; unique filamentous structures and inclusion matrices were apparent in the cytoplasm. Complement fixation tests that included purified Cotia virions showed a reciprocal cross-reaction with rabbit myxoma virus and no cross-reaction with vaccinia virus. Serological results coupled with gradient polyacrylamide gel electropherograms of the structural proteins of purified Cotia, vaccinia, myxoma and fibroma viruses suggested that Cotia virus was similar to the latter two viruses. Agarose gel electropherograms of cleavage fragments of each of these virus DNAs digested with three separate restriction endonucleases showed that each of these viruses had a unique DNA gel profile.

Replication of influenza virus at elevated temperatures: Production of virus-like particles with reduced matrix protein content☆

Abstract The average matrix protein content in virions of wild-type influenza A/Ann Arbor/6/ 60 (H2N2) or A/Queensland/6/72(H3N2) is reduced by about half when virus is grown in chick kidney cells at 39° instead of at 34°. This results from the production at 39° of a subpopulation of virions having a low buoyant density ( P = 1.14 g/cm 3 ) and having as matrix protein only about 5 to 10% of their total protein, in contrast to normal virions with a matrix protein content of approximately 50% and a buoyant density of 1.20 g/cm 3 . Although the virions comprising the low density subpopulation have little matrix protein, they contain approximately normal proportions of hemagglutinin and nucleoprotein. This suggests that matrix protein may not be essential for maturation of influenza virions containing nucleoprotein and viral modified membrane. However, as judged by their morphology, the virions with a reduced matrix protein content appeared more fragile than normal virions, which implies that a major role for matrix protein is maintaining the structural integrity of influenza virus particles.

Ultrastructure of human immunodeficiency virus type 2.

The ultrastructure of human immunodeficiency virus type 2 (HIV-2) was determined by negative stain and thin section electron microscopy (EM). Some virus particles had surface projections about 10 nm in length which were evenly spaced. Nonidet P40-treated particles which were penetrated by stain revealed a distinctive off-centre cone-shaped core and, in addition, free-lying cores were also seen in detergent-treated preparations. The surface of the cores was composed of a layer of small subunits. The structure of HIV-2 determined by thin section EM was the same as that deduced by negative stain EM.

The fine structure of the capsid of reovirus type 3

Abstract The fine structure of the outer capsid of reovirus type 3 was studied by negative contrast electron microscopy and enhancement of image detail by rotational analysis. The capsid was found to be composed of large morphological units, or capsomeres, measuring 18 nm in diameter. Hexagonal units are composed of six separate wedgeshaped subunits which are in turn made up of three smaller subunits. The architecture of the capsid appears to be that of a T = 3 morphology with a probable 32 morphological units which themselves have the more complex symmetry of a T = 9 icosadeltahedron. A prominent feature of the architecture of the capsid was found to be a sharing of subunits, an apparently unique feature of viruses in the Reoviridae virus family.

Biochemical Characterization of Infantile Gastroenteritis Virus (IGV)

Enzymic and biophysical studies with purified infantile gastroenteritis virus (IGV) nucleic acid indicated that the virion contained a double-stranded RNA genome of approx. 14 x 10(6) daltons which could be separated by gel electrophoresis into eight bands of RNA which were comprised of 15 RNA species. Two major virus proteins, VP2 (mol. wt. = 135,000) and VP8 (mol. wt. = 40,000), which composed about 85% of the total virion protein, were detected in IGV particles by polyacrylamide gel electrophoresis. Eight additional minor proteins were also resolved.

Further Observations on the Ultrastructure of Human Rotavirus

The inner capsid layer of human rotavirus was found to preferentially break up into large ring-like morphological units. The outer capsid was found to be composed of capsomeres covered by a thin protein or glycoprotein covering. These capsomeres appeared to be broad headed and short stemmed, similar to the type of pin used to mark locations on a map (pushpin).