Thermal Inactivation of Newcastle Disease Virus

The rate of destruction of hemagglutinins and infectivity of Newcastle disease virus was determined over a temperature range of 37.8 to 60 C. From the calculated values of deltaH and deltaS, it was concluded that inactivation of the hemagglutinating activity and viral infectivity was due to protein denaturation.     

Effects of temperature on virus-host relationships and on activity of the noninclusion virus of citrus red mites, Panonychus citri

The nonoccluded virus of citrus red mite retained full infectivity when exposed to 40.5°C for 24 hr within intact mite bodies but was inactivated at 46°C for 6 hr and 60°C for 1 hr. Exposures to 38°C for 28 days failed to destroy infectivity. Virus inoculated mites exposed to different temperature regimens had shortened periods of lethal infection at high temperatures and greatly lengthened periods of lethal infection at cool temperatures suggesting that failures in mite control by virus in the early spring and late fall may be due to previously unrecognized temperature relationships.     

Persistence of avian influenza viruses in lake sediment, duck feces, and duck meat

The persistence of 3 low-pathogenicity avian influenza viruses (LPAIV) (H4N6, H5N1, and H6N8) and one human influenza virus (H1N1) as well as Newcastle disease virus (NDV) and enteric cytopathogenic bovine orphan (ECBO) virus was investigated in lake sediment, duck feces, and duck meat at 30, 20, 10, and 0°C using a germ carrier technique. Virus-loaded germ carriers were incubated in each substrate, and residual infectivity of the eluted virus was quantified on cell culture after regular intervals for a maximum of 24 weeks. Data were analyzed by a linear regression model to calculate T(90) values (time required for 90% loss of virus infectivity) and estimated persistence of the viruses. In general, the persistence of all of the viruses was highest in lake sediment, followed by feces, and was the lowest in duck meat at all temperatures. For the avian influenza virus subtypes, T(90) values in sediment ranged from 5 to 11, 13 to 18, 43 to 54, and 66 to 394 days at 30, 20, 10, and 0°C, respectively, which were 2 to 5 times higher than the T(90) values of the viruses in the feces and meat. Although the individual viruses vary in tenacity, the survival time of influenza viruses was shorter than that of NDV and ECBO virus in all substrates. The results of this study suggest that lake sediment may act as a long-term source of influenza viruses in the aquatic habitat, while the viruses may remain infectious for extended periods of time in duck feces and meat at low temperatures, allowing persistence of the viruses in the environment over winter.     

Integrity of membrane lipid rafts is necessary for the ordered assembly and release of infectious Newcastle disease virus particles

Membrane lipid raft domains are thought to be sites of assembly for many enveloped viruses. The roles of both classical lipid rafts and lipid rafts associated with the membrane cytoskeleton in the assembly of Newcastle disease virus (NDV) were investigated. The lipid raft-associated proteins caveolin-1, flotillin-2, and actin were incorporated into virions, while the non-lipid raft-associated transferrin receptor was excluded. Kinetic analyses of the distribution of viral proteins in lipid rafts, as defined by detergent-resistant membranes (DRMs), in non-lipid raft membranes, and in virions showed an accumulation of HN, F, and NP viral proteins in lipid rafts early after synthesis. Subsequently, these proteins exited the DRMs and were recovered quantitatively in purified virions, while levels of these proteins in detergent-soluble cell fractions remained relatively constant. Cholesterol depletion of infected cells drastically altered the association of viral proteins with DRMs and resulted in an enhanced release of virus particles with reduced infectivity. Decreased infectivity was not due to effects on subsequent virus entry, since the extraction of cholesterol from intact virus did not significantly reduce infectivity. Particles released from cholesterol-depleted cells had very heterogeneous densities and altered ratios of NP and glycoproteins, demonstrating structural abnormalities which potentially contributed to their lowered infectivity. Taken together, these results indicate that lipid rafts, including cytoskeleton-associated lipid rafts, are sites of NDV assembly and that these domains are important for ordered assembly and release of infectious Newcastle disease virus particles.     

Temperature-Dependent Inhibition of Fusion from Without

Fusion from without by Newcastle disease virus is inhibited by incubation at 23 C. The inhibitory effect is exerted at a step after viral attachment and is not reversed by subsequent incubation at higher temperatures.     

Molecular events during the interaction of envelopes of myxo- and RNA-tumor viruses with cell membranes. A 270 MHz 1H nuclear magnetic resonance study

The nuclear magnetic resonance (NMR) spectra of chick embryo cells have been analyzed after exposure to Newcastle disease virus (NDV). Virions that contained the envelope glycoproteins in the cleaved form and, thus, had full biological activity have been compared to virions that had reduced infectivity due to the presence of uncleaved glycoprotein F. After exposure to infectious virus, drastic changes occurred in the signals assigned to choline and the hydrocarbon chains of fatty acids. These observations are interpreted to demonstrate alteration of the fluid lipid bilayer structure of the cell membranes. This is compatible with the concept of membrane fusion as a penetration mechanism for NDV. Virus containing uncleaved F glycoprotein did not alter the NMR spectra. This indicates that infection is blocked at the stage of penetration.Similar, though less pronounced, differences have been observed when the effects of highly infectious influenza virus containing the hemagglutinin in the cleaved form were compared to the effects of virus which had a lower infectivity due to the presence of uncleaved hemagglutinin. Thus, it appears that the hemagglutinin of influenza virus is involved in penetration and that cleavage is necessary for this function.Alterations of the NMR spectra of the membrane lipids have also been observed when susceptible chick embryo cells (C/E) were infected with Rous sarcoma virus of subgroup B. Such alterations did not occur when nonsusceptible cells (C/B) were used. Thus, infection appears to be blocked again at the stage of penetration.     

Stability of Minute Virus of Mice to Chemical and Physical Agents

Minute virus of mice (MVM), a single-stranded deoxyribonucleic acid Parvovirus, was subjected to various inactivation procedures, including chemical disinfectants, heat, and ultraviolet radiation. MVM was found to be less stable than has been reported for other Parvoviruses. This virus was readily inactivated by a variety of chemical disinfectants, including alcohols, formaldehyde, glutaraldehyde, and chloroform. MVM was more sensitive to ultraviolet radiation than was Kilham's rat virus. MVM was more sensitive to heating at temperatures of 35 to 100 C than has been reported for other Parvoviruses. More than 95% of MVM infectivity was inactivated by heating (45, 60, or 100 C) for 60 min, acid (pH 2.0) treatment, or ultraviolet radiation treatment, although a small percentage (less than 2%) of the virus preparation was found to be resistant to these treatments. In addition, more than 99% of the infectivity of MVM was lost after storage at 4C for 10 weeks, although the virus was stable on storage in liquid nitrogen.     

pH-stability patterns of some strains of Newcastle disease and fowl-plague viruses

Summary The strains of fowl-plague virus being tested completely lost their infectivity to chick embryos when stored at p_H 4 for one hour or more while those of the virus of Newcastle disease were all infective to chick embryos when stored at this p_H-value for periods up to 7 days.     

Protection of Measles Virus by Sulfate Ions Against Thermal Inactivation.

Rapp, Fred (Baylor University College of Medicine, Houston, Tex.), Janet S. Butel, and Craig Wallis. Protection of measles virus by sulfate ions against thermal inactivation. J. Bacteriol. 90:132-135. 1965.-The infectivity of measles virus in water is rapidly destroyed at temperatures of 37 C and above. More than 50% of the infectivity is lost after 1 hr at 25 C, and almost 90% loss of infectivity occurs within 24 hr at 4 C. Magnesium chloride enhances the inactivation of the virus at all temperatures tested. Addition of either magnesium or sodium sulfate protects the virus against thermal inactivation. The stabilizing effect is demonstrable at temperatures ranging from 4 to 56 C, but is especially pronounced through 45 C. Prolonged storage (up to 6 weeks) of the virulent virus at 4 C in 1 m magnesium sulfate permits retention of substantial infectivity, whereas storage at 4 C in either water or 1 m magnesium chloride results in a loss of infectivity approximating 99% after 2 weeks. Magnesium chloride also enhances inactivation of the attenuated vaccine strain of measles virus. The attenuated virus, however, is strongly protected by magnesium sulfate against thermal inactivation, and retention of infectivity for long periods of time at 4 C seems feasible when the virus is kept in 1 m magnesium sulfate.     

Elimination of Mycoplasma Contaminants from Virus Stocks by Treatment with Nonionic Detergents

Five nonionic detergents (Tweens 20, 40, 60, and 80, and Triton WR-1339) were tested for their ability to inactivate four Mycoplasma species which are common contaminants of animal cell cultures. Tween 20 was found to be the most effective, in that a concentration of 2.5 mg/ml completely inactivated cultures of M. hominis, M. hyorhinis, and Acholeplasma laidlawii within 1 hr and a culture of M. orale within 3 hr. The other detergents exhibited various degree of activity against the different mycoplasmas, with Triton WR-1339 being the least effective. The virucidal activity of the detergents was determined for six viruses. All four Tween compounds were highly virucidal for herpes simplex virus. Tween 20 also exhibited virucidal effects against vesicular stomatitis virus, California encephalitis virus, and Newcastle disease virus, and Tween 80 was found to be active against California encephalitis and Newcastle disease viruses. Detergent treatment procedures were effective in two instances in eliminating mycoplasma contaminants from virus preparations while the preparations retained most of the viral infectivity. The limitations of this technique for routine use are discussed.     

The effect of delayed harvesting as well as freezing and thawing on biological properties of Newcastle disease virus

Delayed harvest of Newcastle disease virus (NDV) from eggs was less infective (as expressed by its lower infectious titer and a higher number of virus particles per EID50) and more resistant to a temperature of 50 degrees C than the early harvest. On the other hand, little or no effect of delayed harvesting was found on neuraminidase, erythrocyte-fusing and immunogenic properties. Moreover, haemolytic activity of NDV was moderately enhanced when its harvesting from de-embryonated egg was delayed. Treatment of a fresh NDV preparation with repeated freezing and thawing cycles also caused a marked reduction in virus infectivity and induction of its haemolytic activity.     

Isolation and Characterization of Defective Interfering Particle of Newcastle Disease Virus

Newcastle disease virus grown in embryonated eggs was separated and purified by sucrose density gradient centrifugation into two distinct types of particles, B and T, the former being normal virus particles with high activities of hemagglutination, hemolysis, neuraminidase and infectivity, the latter being non-infectious virus particles with low activities of hemolysis and neuraminidase but high hemagglutination activity. B and T particles were shown to share a common antigen by immunodiffusion test. T particles were deficient in viral RNA, since they contained only 13s RNA in a small amount, whereas B particles possessed a large amount of 57s RNA and a small amount of 13s RNA. T particles interfered with the multiplication of normal Newcastle disease virus in primary cultures of chick embryo cells.     

Analysis of transmembrane dynamics of cholera toxin using photoreactive probes

Using sodium dodecyl sulfate--polyacrylamide gel electrophoresis and autoradiography, we have shown that ¹²⁵I-labeled cholera toxin binds to Newcastle disease virus. Pretreatment of Newcastle disease virus with “cold” cholera toxin (at 37°C for 30 minutes) inhibits the binding of ¹²⁵I-labeled toxin in a subsequent incubation (at 37°C for 30 minutes). These results suggest that cholera toxin binds to Newcastle disease virus in a specific manner. The precise receptor for toxin is unknown in Newcastle disease virus but it is presumed to be the ganglioside GM₁. We have previously shown that the photoreactive probe 12-(4-azido-2-nitrophenoxy)stearoylgucosamine[1-¹⁴C] labels the membrane proteins of Newcastle disease virus. Since the reactive group of the probe, ie, N₃, resides within the membrane bilayer, studies were initiated to determine which, if any, of the subunits of cholera toxin cross the membrane of Newcastle disease virus and become radioactively labeled upon photoactivation of the probe at 360 nm. After a 15-minute incubation of cholera toxin with Newcastle disease virus containing the photoreactive probe, irradiation effected the ¹⁴C-labeling of the active A₁ subunit of cholera toxin. Irradiation of cholera toxin in solution with an equivalent amount of probe but without virus resulted in no labeling of toxin subunits.     

A temperature-sensitive mutant of Newcastle disease virus defective in intracellular processing of fusion protein.

A temperature-sensitive mutant (ts3) of Newcastle disease virus was physiologically characterized. All major viral structural proteins were synthesized at the permissive (37 degrees C) and nonpermissive (42 degrees C) temperatures, but the fusion (F) glycoprotein was not cleaved at 42 degrees C. In immunocytochemical electron microscopy, the F protein was abundant in the rough endoplasmic reticulum but not in cytoplasmic membrane at 42 degrees C. Noninfectious hemagglutinating virus particles containing all major structural proteins except the F protein were released at 42 degrees C from infected cells. We concluded that the defect in ts3 resides in the intracellular processing of the F protein.     

Gangliosides and N-glycoproteins function as Newcastle disease virus receptors

The interaction of enveloped viruses with cell surface receptors is the first step in the viral cycle and an important determinant of viral host range. Although it is established that the paramyxovirus Newcastle Disease Virus binds to sialic acid-containing glycoconjugates the exact nature of the receptors has not yet been determined. Accordingly, here we attempted to characterize the cellular receptors for Newcastle disease virus. Treatment of cells with tunicamycin, an inhibitor of protein N-glycosylation, blocked fusion and infectivity, while the inhibitor of O-glycosylation benzyl-N-acetyl-alpha-D-galactosamide had no effect. Additionally, the inhibitor of glycolipid biosynthesis 1-phenyl-2-hexadecanoylamino-3-morpholino-1-propanol blocked viral fusion and infectivity. These results suggest that N-linked glycoproteins and glycolipids would be involved in viral entry but not O-linked glycoproteins. The ganglioside content of COS-7 cells was analyzed showing that GD1a was the major ganglioside component; the presence of GM1, GM2 and GM3 was also established. In a thin-layer chromatographic binding assay, we analyzed the binding of the virus to different gangliosides, detecting the interaction with monosialogangliosides such as GM3, GM2 and GM1; disialogangliosides such as GD1a and GD1b, and trisialogangliosides such as GT1b. Unlike with other viruses, our results seem to point to the absence of a specific pattern of gangliosides that interact with Newcastle disease virus. In conclusion, our results suggest that Newcastle disease virus requires different sialic acid-containing compounds, gangliosides and glycoproteins for entry into the target cell. We propose that gangliosides would act as primary receptors while N-linked glycoproteins would function as the second receptor critical for viral entry.     

Properties of influenza C virus grown in cell culture.

Influenza C virus was propagated successfully in primary chicken embryo lung (CEL) and fibroblast cells and in Madin-Darby canine kidney (MDCK) cells. In other cell lines, either no virus or only noninfectious hemagglutinin (HA) was produced. In productively infected cells (CEL), HA and infectious virus appeared by 24 h and reached a maximum by 36 to 48 h, cell-associated virus remaining at a constant low level. Infected Vero cells produced noninfective HA by 24 h which also remained predominantly cell associated until 60 to 72 h, when the cells disintegrated. Viral antigen was demonstrable on membranes of both CEL- and Vero-infected cells at 24 h; Vero cells yielded membrane vesicles containing HA, but none of the spherical or filamentous viral particles synthesized in CEL cells. Influenza C virus produced in cell culture or in eggs differed in several important respects from A and B viruses and from Newcastle diseases virus. All influenza C preparations, regardless of infectivity or source, lacked detectable neuraminidase activity, yet retained the ability specifically to inactivate receptors only for influenza C. Influenza C HA was not inhibited by soluble glycoproteins highly active against HA of A virus. A rat serum glycoprotein uniquely inhibited influenza C by binding to the surface components of virious.     

香菇C91-3菌株发酵液对副流感病毒和新城疫病毒血细胞吸附的抑制作用

目的探讨香菇C91-3菌株发酵液的抗病毒作用。方法应用香菇C91-3菌株发酵液不同稀释度分别作用于副流感病毒和新城疫病毒,观察其对血细胞吸附作用的影响。结果香菇C91-3菌株发酵液原液组和1:2稀释组对副流感病毒和新城疫病毒的血细胞吸附均有抑制作用。结论香菇C91-3菌株发酵液有明显的抗病毒作用。     

Effect of Administered Interferon on Rabies in Rabbits

This study describes the effect of interferon on the survival of rabbits infected with a street strain of rabies virus. Interferon was prepared by collecting serum from rabbits injected with Newcastle disease virus and was characterized by biological and physicochemical methods. Rabbit serum interferon mixed and incubated with a suspension of rabies virus did not neutralize its infectivity. Rabbits were inoculated into the hind leg muscle with approximately 80 LD(50) of virus. Interferon was administered intravenously or intramuscularly, or by both methods, in the same or opposite leg as virus. Mortality due to rabies was significantly reduced by the concurrent administration of 8 x 10(5) units of interferon divided between the site of virus inoculation and intravenously. There was less protection if 3 hr elapsed between the inoculation of virus and interferon. Treatment given 24 hr after infection did not prevent death but prolonged the incubation period.     

Response of some strains of Newcastle disease and fowl-plague viruses to two quinones

Summary Comparative studies of the response of some Egyptian strains of Newcastle disease and fowl-plague viruses to tolu- and thymoquinones revealed that the two quinones appreciably reduced the infectivity, but not the hemagglutinative powers of the virus strains, toluquinone being more effective in this respect than thymoquinone. The different viruses or virus strains responded differently to the two quinones.     

The thermal death time curve for foot-and-mouth disease virus contained in primarily infected milk

Whole and skim milk obtained from cows after intramammary and intravenous inoculation with foot-and-mouth disease virus (primarily infected milk) were exposed to various temperatures ranging from 80 to 148 degrees C for various times ranging from 2.5 s to 27 min then tested for viral infectivity. The average pretreatment titre of the 53 lots of milk used was 10(5.9) plaque-forming units of virus per millilitre 10(3.7)-10(6.8)). A thermal death time curve was plotted using the data obtained. The curve demonstrates that in order to inactivate the virus, times of over 20 min are necessary at 'low' temperatures (100 degrees C) while 2.5 s is sufficient at a temperature of 148 degrees C.