Marmoset lymphoblastoid cells as a sensitive host for isolation of measles virus

B95-8, an Epstein-Barr virus-transformed marmoset B-lymphoblastoid cell line, and its derivative B95a, capable of attachment to a substrate surface, were 10,000-fold more sensitive to measles virus present in clinical specimens than were Vero cells. B95-8 and B95a cells were thus thought to be useful host cells for the isolation of measles virus. Quantitation of measles virus present in clinical specimens showed that a large quantity of virus, exceeding 10(6) 50% tissue culture infective doses per ml of a nasal-swab eluate, is shed into secretions by patients with acute measles, consistent with the contagiousness of the disease. Measles viruses isolated in B95a cells differed in some biological properties from those adapted to Vero cells. First, the viruses isolated in B95a cells did replicate in Vero cells, but release into the fluid phase was less efficient than that of Vero cell-adapted viruses. Second, minor antigenic differences were found between virus strains isolated in B95a cells and those isolated in Vero cells from the same clinical specimens. Third, the viruses isolated and propagated in B95a cells caused clinical signs in experimentally infected monkeys resembling those of human measles. It was suspected that measles virus is subject to host cell-mediated selection and that the viruses grown in B95a cells are more representative of measles virus circulating among humans than are the viruses selected in Vero cells.

Sequence variation of the P gene among mumps virus strains

We have determined nucleotide sequences of a 183-nucleotide long region of the P gene of 10 mumps virus strains after gene amplification mediated by DNA polymerase catalyzed chain reaction (PCR) and have compared them with those of two strains which had been reported earlier (K. Takeuchi et al., J. Gen. Virol., 69, 2043-2049 (1988]. It was shown that mutation is generally noncumulative, i.e., most nucleotide substitutions in earlier strains do not appear in later strains. Viruses of different lineages appeared to cocirculate, but the comparison of American and Japanese strains suggested that those isolated in one country are more closely related to each other than to those isolated in the other country.

A measles virus subgenomic RNA: structure and generation mechanism

A plaque-derived line of measles virus induced the synthesis of 21S subgenomic RNA in addition to 50S genomic RNA. The nucleotide sequence of the former RNA was determined in comparison with that of the latter. The 21S subgenomic RNA was 2646 nucleotides long and had a copyback structure containing a 50S genomic 5'-end. At the site where copying turns back, there was a 15-nucleotide-long sequence resembling the "measles virus consensus sequence" which is present at the beginning of each gene on the measles virus genome and is presumed to serve as a signal for the initiation of transcription. Recognition of the specific sequence may have been involved in the aberrant replication and may represent an additional and novel copy choice mechanism leading to the generation of subgenomic RNAs.

Matrix protein of cell-associated subacute sclerosing panencephalitis viruses

The nucleotide sequence has been determined for the matrix (M) protein gene of three strains, Niigata-1, ZH and Biken, of cell-associated subacute sclerosing panencephalitis (SSPE) virus. The M proteins of the Niigata-1 and ZH strains were found to terminate prematurely as a result of nonsense mutations at nucleotide positions 68 and 96 respectively. On the other hand it was predicted that the Biken strain would express M protein with 22 amino acid differences and eight additional amino acids at its C terminus in comparison to the M protein of the Edmonston strain of measles virus. Radiolabelling of cells carrying the Biken strain showed the production of an M protein with considerably altered immunoreactivity and a marked reduction in intracellular stability. Either premature termination or rapid degradation of the M protein may underlie the defectiveness of these three strains of SSPE virus.

Protective role of human antibody to the fusion protein of measles virus

Absorption of a pooled human gamma globulin preparation with acetone-treated measles virus-infected cells removed all antibodies to measles virus antigens except a portion of the antibody to the fusion (F) protein. The residual anti-F antibody had hemolysis-inhibiting and virus-neutralizing activities, inhibited spread of infection through cell fusion, and was effective in protection of passively immunized mice from fatal measles encephalitis, providing evidence for the protective role of human antibody to the F protein of measles virus.

Single-serum diagnosis of recent rubella infection with the use of hemagglutination inhibition test and enzyme-linked immunosorbent assays

Single-serum diagnosis of recent rubella infection was attempted with the use of hemagglutination inhibition (HI) test and two commercially available enzyme-linked immunosorbent assays (ELISAs). The period during which IgM antibody was detectable by IgM capture ELISA was 4 to 30 days after the onset of rash. Rubella IgG ELISA values relative to HI titer were lower in the sera from the patients with recent infection than in the sera from the subjects with remote infection. IgM ELISA and the combined use of IgG ELISA and HI test are two useful methods of single-serum diagnosis of recent rubella infection.

Low pH-induced conformational change of rubella virus envelope proteins

Fusion of rubella virus-infected cells was induced by their brief treatment at pH below 6.0. Exposure of rubella virus to pH 5 caused an irreversible conformational change of the viral envelope glycoproteins, E1 and E2. The change was manifested in the marked reduction in both infectivity and haemagglutinating activity of the virus, the increased resistance of E1 and decreased resistance of E2 polypeptides to proteolytic digestion with trypsin, and the acquisition of liposome-binding activity of the virus. The above changes are presumed to mimic the events occurring in the acidic environment within endosomes following endocytosis of the virus.

Complement-mediated neutralization test for determination of mumps vaccine-induced antibody

When assessed by a conventional plaque neutralization (NT) test, about one third of recipients of live mumps vaccine were found to have failed to seroconvert, although the majority of them became seropositive by the complement-mediated neutralization (CNT) test. The discrepancy between the conventional NT and CNT was found to result from two factors. First, the predominant production of antibodies to the fusion (F) protein during the early phase of antibody response, and second, a low efficiency of NT of the early antibodies in the absence of complement. These features of antibody response were also seen in natural mumps infection and in experimental infection of monkeys, but were particularly prominent in vaccinees because of the limited extent of antibody response in the latter. The discrepancy between conventional NT and CNT diminished with time after vaccination, after natural infection, and also after experimental infection of monkeys. The CNT test was therefore considered better suited than the conventional NT test for assessment of the outcome of vaccination, at least until 6 to 9 weeks after vaccination. The protective role of the antibody in vivo, which requires the addition of complement for neutralization, was inferred from the observation that the antibody incorporated in the agar overlay significantly reduced the size of plaques formed by mumps virus.

Molecular cloning and sequence analysis of the mumps virus gene encoding the P protein: mumps virus P gene is monocistronic

The nucleotide sequence of the P (phosphoprotein) gene of two strains of mumps virus has been determined from overlapping cDNA clones. The P gene contained a single open reading frame coding for a protein of 391 amino acids with a calculated Mr of 41,587, in good agreement with the value (40K to 45K) estimated from electrophoretic mobility on SDS-polyacrylamide gels. No open reading frame analogous to the C gene of other paramyxoviruses existed in the mumps virus P gene region. Comparison of the amino acid sequence of the mumps virus P protein with that of Newcastle disease virus showed a limited sequence homology.

Conformational change of rubella virus spike proteins induced by 2-mercaptoethanol

Hemagglutinating (HA) activity of rubella virus was inactivated with 2-mercaptoethanol (2ME) in a dose-dependent manner. But even low concentrations of 2ME, which had little effect on HA activity by themselves, greatly increased the sensitivity of spike polypeptides to the subsequent trypsin treatment. Increased trypsin sensitivity was shown by an enhanced reduction of HA activity and an enhanced proteolytic removal of both E1 and E2 polypeptides from the surface of the virion. The findings indicate that 2ME causes an extensive disruption in the conformation of spikes composed of E1 and E2 polypeptides.

Passive hemagglutination test for measles immunity and serodiagnosis

A passive hemagglutination (PHA) test for measles was evaluated in comparison with hemagglutination inhibition (HI) and neutralization (NT) tests. The PHA test determines exclusively the level of antibody directed to the hemagglutinin protein of measles virus. The ratio of PHA to HI titer was 1 to 32 (geometric mean, 6.5) for the first 5 weeks of infection but declined to near unity thereafter. It gradually increased again to 4 to 32 (geometric mean, 11.7) over several years. The initial high PHA titer relative to the HI titer was most likely due to the presence of the immunoglobulin M antibody known to be efficient in agglutination, because 2-mercaptoethanol (2ME) treatment of sera reduced the PHA titer to a level similar to that of the HI titer. The PHA titer in sera obtained after the convalescent phase was insensitive to 2ME, and the relative increase in the PHA over the HI titer was presumably a result of increased antibody avidity. In some individuals, the HI titer fell to below detectable levels several years after either natural infection or vaccination, but the PHA as well as the NT titer remained positive. The PHA titer was therefore a more reliable and more sensitive indicator of immune status against measles than the HI titer. The decrease in PHA titer by 2ME treatment provided evidence of a current or very recent infection. PHA was found to be useful both for assessing immunity status and for serodiagnosis.

Intracellular processing of measles virus fusion protein

Intracellular processing of measles virus fusion (F) protein was studied by radiolabeling and immunoprecipitation with a monoclonal antibody against F protein. The cleavage of F protein into F1 and F2 subunits was complete after 5 hours of chase during which the growth of oligosaccharide chains on the F2 domain of F protein continued. The addition of terminal sialic acid conferred a strong negative charge on the F2 subunit. F protein expressed on the cell surface was removed by a fungal semi-alkaline protease, providing a method to follow the kinetics of its transport to the cell surface. The transport of the F protein was faster than that of the hemagglutinin (HA) protein. Uncleaved F protein, as well as cleaved subunits became digestible by the protease, indicating that a portion of the F protein reaches the cell surface uncleaved. The treatment of measles virus-infected cells with tunicamycin resulted in the synthesis of unglycosylated HA (65 kilodaltons, Kd) and F (48 Kd) proteins. Unglycosylated F protein was not cleaved into smaller subunits, nor was it transported to the cell surface. Unglycosylated HA protein likewise failed to reach the cell surface.

Sudden deafness and asymptomatic mumps

Adult patients who had experienced sudden deafness were examined for possible presence of subclinical mumps infection, using a new method of detecting mumps IgM antibody. Three of 53 patients demonstrated a positive reaction, indicating a strong correlation of sudden deafness with recent mumps infection. Mumps vaccination is recommended for those who have one deaf ear, in order to protect the better ear from mumps infection.

Experimental mumps labyrinthitis in monkeys (Macaca irus)--immunohistochemical and ultrastructural studies

Three monkeys (Macaca irus) were inoculated with mumps virus into unilateral cochleas and their inner ear were examined by immunofluorescent microscopy and transmission electronmicroscopy. The temporal bones were removed after survival period of 14 days when serological tests disclosed elevation of anti-mumps antibody titers. Immunofluorescent microscopy revealed that the viral antigen was positive in the stria vascularis. The ultrastructural study revealed that the pathologic changes in the cochleas were marked in the organ of Corti and stria vascularis. The outer hair cells were more susceptible to the infection than the inner hair cells. In the stria vascularis, both marginal and intermediate cells were affected. It was possible to find some of marginal cells in the basal turn shedding a large number of mature virions into the endolymph. These pathologic changes observed in the cochleas of the monkeys were similar to those previously revealed in the guinea pig cochleas and thus were considered as the specific features of acute mumps labyrinthitis.

Effects of antipyretics in rinderpest virus infection in rabbits

Administration of acetylsalicylic acid or mefenamic acid during experimental infection of rabbits with a rabbit-adapted strain of rinderpest virus did not prevent initiation of the febrile response but significantly reduced the duration of fever. Suppression of fever had a markedly deleterious effect on the course of infection, resulting in an increased content of infectious virus in the mesenteric lymph nodes, increased mortality, and retarded recovery in animals that survived the infection. Histological lesions were mainly lymphocytic depletion in lymphoid organs and lymphoid necrosis in both rabbits treated with antipyretics and those left untreated, but damage was more pronounced in the former than in the latter. More viral antigen was detected by immunofluorescence in lymphoid organs of drug-treated rabbits than in those of untreated rabbits. Antipyretic treatment resulted in higher serum interferon levels in the early phase of infection and an increased antibody response in animals that survived the infection.

Protective effect of antibodies to two viral envelope glycoproteins on lethal infection with Newcastle disease virus

The protective effect of humoral immunity against lethal infection of chickens with Newcastle disease virus was studied. Chickens hatched from eggs laid by hens vaccinated with live attenuated Newcastle disease virus vaccine possessed antibody to various components of the virus, and were resistant to a challenge with a virulent strain of Newcastle disease virus which was 100 per cent fatal for the offspring of nonvaccinated hens. Passive administration of antiserum raised against whole virions provided susceptible chickens protection comparable to that seen in the birds with maternal antibody. When administered passively, both anti-HN serum with virus neutralizing activity, and anti-F serum with only marginal virus neutralizing activity significantly prolonged the survival of infected birds but failed to achieve the level of protection as afforded by the anti-whole NDV serum. The protection provided by the simultaneous presence of anti-HN and anti-F serum was significantly greater than that afforded by either alone and comparable to that of anti-whole NDV serum, indicating the complementary effect of anti-HN and anti-F antibodies not only in cell cultures as reported previously (19), but also in a natural host.

Immunocytochemical focus assay for potency determination of measles-mumps-rubella trivalent vaccine

The immunocytochemically stained focus assay for the determination of potency of individual components in measles-mumps-rubella trivalent vaccine is described. The method involves the reaction of infected cultures maintained under the agar overlay medium sequentially with rabbit antiserum specific to each component, biotinylated anti-rabbit IgG serum, avidin-biotinylated-peroxidase complex, and substrate mixture. The potency of one component determined by the method was not influenced by the presence of two other components and was comparable to that determined by either dilution end point titration or plaque assay. The method offers a number of advantages over the current method based on neutralization of components other than the one to be titrated.

Identification of the defects in the hemagglutinin gene of two temperature-sensitive mutants of A/WSN/33 influenza virus

Two temperature-sensitive mutants of WSN influenza virus, ts-61S and ts-134, possess defects in the hemagglutinin (HA) gene. These defects are characterized as a defective intracellular transport of the HA at the nonpermissive temperature and a marked thermolability. The nucleic acid sequences of the HA gene of these two viruses, as well as a series of revertant viruses, were determined. The deduced amino acid sequences demonstrate that the HA of ts-61S varied from the wild type protein by three amino acids while that of ts-134 differed by two residues. For both mutants, analysis of revertant viruses indicated that the phenotype of transport inhibition at the nonpermissive temperature and heat lability were associated with a single amino acid change in the globular portion of the molecule. In the case of ts-61S, the critical change in the HA was the replacement of a serine residue at position 110 with that of a proline. The mutational defect in the HA of ts-134 was due to the substitution of a tyrosine residue at position 159 with that of a histidine residue. Four of five revertants of ts-134 were suppressor revertants, of which some of the compensatory changes did not restore thermostability to the HA.

Effect of carboxylic ionophores on measles virus hemagglutinin protein

We have studied the effect of two carboxylic ionophores, monensin and laidlomycin, on the replication of measles virus in KB cells. The yield of infectious virus was markedly depressed at the concentrations of the ionophores which had no effect on overall viral protein synthesis. The ionophores selectively blocked the migration of hemagglutinin (H) glycoprotein from Golgi apparatus to the cell surface. As a result, H glycoprotein is prevented from being converted from incompletely glycosylated form to the mature form. The inhibitory effect on the transport and glycosylation of H was reversed, although gradually, upon the removal of the ionophores.

Treatment of low cardiac output complicating acute pulmonary hypertension in normovolemic goats

In eight anesthetized ventilated goats, the hemodynamic effect of isoproterenol (ISU), dopamine (DOP), norepinephrine (NE), nitroglycerin (NTG), and Ringer's lactate (RL) infusion was evaluated after inducing acute pulmonary hypertension (PHN) to decrease cardiac output. Therapy with ISU significantly (p less than .05) increased cardiac output, but also increased transmural right ventricular end-diastolic pressure (RVEDPTM) and heart rate (HR) and decreased stroke volume (SV) and right ventricular ejection fraction (RVEF). NE increased cardiac output, mean arterial pressure (MAP), systemic vascular resistance (SVR), and RVEF. DOP decreased pulmonary vascular resistance (PVR) and increased cardiac output, MAP, and RVEF, but also significantly increased HR. NTG increased cardiac output and RVEF while decreasing SVR and PVR. Intravascular volume expansion by RL infusion increased cardiac output, SV, and RVEDPTM and decreased HR and PVR. The results of this study indicate that volume loading may be the treatment of choice to restore cardiac output in the face of acute PHN. NE and NTG may be effective as an adjunct therapy. Although ISU and DOP increase cardiac output, the concomitant elevation in HR is undesirable.

Thyrotropin-releasing hormone increases survival in canine hemorrhagic shock

In our previous work thyroidectomy significantly improved survival in canine hemorrhagic shock. This finding, coupled with the reported beneficial hemodynamic effects of thyrotropin-releasing hormone (TRH) in circulatory collapse, led to the present study. Anesthetized, heparinized dogs were bled rapidly into a reservoir until MAP = 40 mm Hg. After 60 min of hypotension (E60) the reservoir line was clamped for 30 min (E90). In 10 dogs three doses of TRH (2 mg/kg) were administered iv at 10-min intervals during clamping. In 11 other animals equivalent volumes of saline were given. At E90 the reservoir line was unclamped, and shed blood was reinfused over 30 min. After 1 hr of monitoring (E180) the dogs were returned to the kennel and observed for at least 3 days. Among 11 control dogs, 6 died. In the TRH group only 1 of 10 dogs died (P less than 0.05). During uncompensated shock (E60-E90), TRH-treated dogs had significantly higher mean arterial pressure, cardiac index, stroke index, and right and left ventricular stroke work indexes, and arterial pH than control animals. At the conclusion of the acute experiment (E180) there were few intergroup hemodynamic-metabolic differences. The significant enhancement of 3-day survival by TRH in canine hemorrhagic shock might be related to hemodynamic improvement at a critical stage of circulatory collapse (E60-E90). Direct or indirect neuromodulatory actions of TRH on the CNS could also explain our results. These findings lend further support to the potentially key role of hypothalamic-pituitary-thyroid interrelationships in shock.