Susceptibility of various animals to the vesiculoviruses Isfahan and Chandipura

To determine the pathogenic potential of the vesiculoviruses Isfahan and Chandipura for domestic animals, two ponies, two steers, three sheep, three goats and three pigs were inoculated with each virus intradermally in the tongue or, in the case of the pigs, in the snout, heel and coronary band. The ponies were also inoculated intradermally in the right commissure of the mouth. Animals inoculated with each virus were housed in one room and allowed to mingle freely with an equal number of uninoculated contact animals of each species. Clinical signs of infection, consisting of ulcers at the inoculation sites, were observed in the Chandipura study in two inoculated ponies, one inoculated steer and one inoculated goat. No elevated temperature was observed. Virus was isolated from the ulcerated tongue tissue, but not from serial blood samples, oesophageal-pharyngeal mucus samples, or from the tissues which were collected at necropsy. Precipitating antibody was not detected by the immunoelectroosmophoresis (IEOP) test in any of the pre- or post-serum samples except from two inoculated sheep at 29 days post-inoculation (D.P.I.). Low levels of neutralizing activity were detected in pre-inoculation serum from all steers, pigs, contact sheep, and one contact goat. By 15 D.P.I. all inoculated animals and contact ponies and steers exhibited increased neutralizing antibody titres. In studies with the Isfahan virus, lesions developed only at the inoculation sites in the two ponies, and the virus was isolated. No virus was isolated from any blood, oesophageal-pharyngeal mucus samples or tissues collected at necropsy. All pre-inoculation sera were negative for neutralizing and precipitating antibodies. By 14 D.P.I. all inoculated animals exhibited neutralizing antibody, while all the contacts remained negative. The IEOP test remained negative for all animals throughout the experiment. A sub-passage of a suspension of Isfahan-infected tongue tissue injected into ponies and steers also yielded only firm swellings of lesser extent than the original reaction at the inoculation sites. With both viruses, lethal infections were produced by intracranial or intraperitoneal inoculation of day-old mice and hamsters, and by allantoic inoculation of embryonating chicken eggs. Adult mice, hamsters, guinea-pigs and rabbits produced serum antibodies but lacked clinical signs.     

Susceptibility of various animals to the vesiculoviruses Isfahan and Chandipura.

To determine the pathogenic potential of the vesiculoviruses Isfahan and Chandipura for domestic animals, two ponies, two steers, three sheep, three goats and three pigs were inoculated with each virus intradermally in the tongue or, in the case of the pigs, in the snout, heel and coronary band. The ponies were also inoculated intradermally in the right commissure of the mouth. Animals inoculated with each virus were housed in one room and allowed to mingle freely with an equal number of uninoculated contact animals of each species. Clinical signs of infection, consisting of ulcers at the inoculation sites, were observed in the Chandipura study in two inoculated ponies, one inoculated steer and one inoculated goat. No elevated temperature was observed. Virus was isolated from the ulcerated tongue tissue, but not from serial blood samples, oesophageal-pharyngeal mucus samples, or from the tissues which were collected at necropsy. Precipitating antibody was not detected by the immunoelectroosmophoresis (IEOP) test in any of the pre- or post-serum samples except from two inoculated sheep at 29 days post-inoculation (D.P.I.). Low levels of neutralizing activity were detected in pre-inoculation serum from all steers, pigs, contact sheep, and one contact goat. By 15 D.P.I. all inoculated animals and contact ponies and steers exhibited increased neutralizing antibody titres. In studies with the Isfahan virus, lesions developed only at the inoculation sites in the two ponies, and the virus was isolated. No virus was isolated from any blood, oesophageal-pharyngeal mucus samples or tissues collected at necropsy. All pre-inoculation sera were negative for neutralizing and precipitating antibodies. By 14 D.P.I. all inoculated animals exhibited neutralizing antibody, while all the contacts remained negative. The IEOP test remained negative for all animals throughout the experiment. A sub-passage of a suspension of Isfahan-infected tongue tissue injected into ponies and steers also yielded only firm swellings of lesser extent than the original reaction at the inoculation sites. With both viruses, lethal infections were produced by intracranial or intraperitoneal inoculation of day-old mice and hamsters, and by allantoic inoculation of embryonating chicken eggs. Adult mice, hamsters, guinea-pigs and rabbits produced serum antibodies but lacked clinical signs.     

In vivo and in vitro studies on temperature-sensitive mutants of swine vesicular disease virus.

Two temperature-sensitive mutants of the Ukg 27/72 strain of swine vesicular disease virus were isolated in tissue culture and a third was derived following adaptation in mice. All three were found to have similar growth restrictive temperatures, but varied considerably in their virulence when administered to pigs. The route of inoculation appeared to exert a considerable influence on the apparent degree of attenuation, the antibody titre engendered and the transmission of disease to pigs held in contact with inoculated animals. One strain appeared almost totally attenuated when inoculated animals. One strain appeared almost totally attenuated when inoculated into pigs but spread to animals in contact causing severe disease. Virus re-isolated from one such animal was found to have retained its temperature sensitive phenotype, suggesting that virulence in this case was not directly related to temperature sensitivity. Pigs with high antibody titres were found to be susceptible when placed in contact with challenge animals, although the lesions which developed were mild.     

Swine vesicular disease: virological studies of experimental infections produced by the England/72 virus

Pigs exposed to relatively small amounts of virus by intradermal inoculation of the feet or by skin sacrification developed clinical disease. Large amounts of virus were recovered from samples taken from the nose, mouth, pharynx, rectum and the prepuce or vagina during the first week of infection and smaller amounts during the second week. Virus was recovered from the faeces of most animals 16 days after infection and from one animal for 23 days. Pigs in contact with inoculated animals were killed at intervals before the appearance of clinical disease. The distribution and amounts of virus in various tissues indicated that infection has most likely gained entry through the skin or the epithelia and mucosae of the digestive tract. Some pigs acquired subclinical infections in which no virus excretion was detected and no transmission of infection to susceptible pigs took place over a period of 5 weeks.     

Development of a Rift Valley fever virus viremia challenge model in sheep and goats

Rift Valley fever virus (RVFV), a member of the family Bunyaviridae, causes severe to fatal disease in newborn ruminants, as well as abortions in pregnant animals; both preventable by vaccination. Availability of a challenge model is a pre-requisite for vaccine efficacy trials. Several modes of inoculation with RVFV ZH501 were tested on goats and sheep. Differences in development of infectious viremia were observed between animals inoculated with RVFV produced in mosquito C6/36 cells compared to Vero E6 cell-produced inoculum. Only C6/36-RVFV inoculation led to development of viremia in all inoculated sheep and goats. The C6/36 cell-produced RVFV appeared to be more infectious with earlier onset of viremia, especially in sheep, and may also more closely represent a field situation. Goats were somewhat more resistant to the disease development with lower and shorter infectious virus viremia, and with only some animals developing transient increase in rectal temperature in contrast to sheep. In conclusion, a challenge protocol suitable for goat and sheep vaccine efficacy studies was developed using subcutaneous inoculation of 10⁷ PFU per animal with RVFV ZH501 produced in C6/36 cells.     

Immune responses of pigs inoculated with a recombinant fowlpox virus coexpressing GP5/GP3 of porcine reproductive and respiratory syndrome virus and swine IL-18

Two recombinant fowlpox viruses (rFPV-ORF5-ORF3 and rFPV-IL-18-ORF5-ORF3) containing the ORF5/ORF3 cDNAs of PRRSV (strain Chang Chun) and IL-18 of swine were constructed and evaluated for theirs abilities to induce humoral and cellular responses in piglets. In addition, their abilities to protect piglets against homologous virus challenge were examined. All piglets were given booster vaccinations at 21 days after the initial inoculation, and all piglets were challenged at 60 after the initial inoculation. Control groups were inoculated with wild-type fowlpox virus (wtFPV). All animals vaccinated with rFPV-ORF5-ORF3 and rFPV-IL-18-ORF5-ORF3 developed specific anti-PRRSV ELISA antibody and neutralizing antibody, as well as T-lymphocyte proliferation response. To evaluate the cellular immune function, IFN-gamma production in pigs serum and T-lymphocytes (CD4 and CD8 T cells) in peripheral blood were examined. Following challenge with a pathogenic strain of PRRSV (strain Chang Chun), piglets inoculated with recombinant fowlpox virus (rFPV) showed lower (P<0.05) temperature, viremia and virus load in bronchial lymph nodes than control animals, suggesting the establishment of partial protection against PRRSV infection. The results demonstrated the potential use of a fowlpox virus-based recombinant vaccine in the control and prevention of PRRSV infections.     

Serological and mucosal immune responses after vaccination and infection with FMDV in pigs

The aim of this study was to determine a possible correlation between humoral immune responses shortly after vaccination and protection against foot-and-mouth disease virus (FMDV) infection and to study the serological and mucosal antibody responses after vaccination and infection. We used three groups of ten pigs, one non-vaccinated group, one group vaccinated with a single dose vaccine and one group vaccinated with a four-fold dose vaccine. At 7 days post vaccination, five pigs per group were challenged intra-dermally with FMDV O TAW 3/97 and the remaining pigs of each group were contact-exposed to the inoculated pigs. In each group, virus excretion and number of contact infections were quantified. The serological and mucosal antibody responses were evaluated until 116 days post infection. Vaccination resulted in a significant decrease of virus excretion. Stepwise linear regression analysis of variables from individual vaccinated pigs revealed the virus excretion after challenge to be correlated with neutralising antibody titres at the day of challenge (p<0.01). In serum and OPF samples comparable isotype-specific antibody responses (IgM, IgG and IgA), could be detected after vaccination as well as after infection. Remarkably, the pigs with the highest IgA responses after vaccination were protected against contact exposure. After infection, a long lasting (up to 116dpi) IgA response was seen in the non-vaccinated and to a lesser extent in the single dose vaccinated pigs. The induction of NSP antibodies in the vaccinated pigs after infection was lower and of shorter duration as compared to the non-vaccinated infected pigs. This experiment shows that vaccination can reduce virus excretion in pigs, which will contribute to reduced transmission of FMDV in the field, even if the pigs are not fully protected. Moreover, vaccines that induce local IgA responses may be more effective, which merits further investigation.     

Differences in the susceptibility of dromedary and Bactrian camels to foot-and-mouth disease virus

In this study, two sheep, eight dromedary camels and two Bactrian camels were inoculated with foot-and-mouth disease virus (FMDV) type A SAU 22/92. Five naive dromedary camels and four sheep were kept in direct or indirect contact with the inoculated camels. The inoculated sheep, which served as positive controls, displayed typical moderate clinical signs of FMD and developed viraemia and high antibody titres. The presence of the virus was also detected in probang and mouth-swab samples for several days after inoculation. In contrast, the inoculated dromedary camels were not susceptible to FMDV type A infection. None of them showed clinical signs of FMD or developed viraemia or specific anti-FMDV antibodies despite the high dose of virus inoculated. All the contact sheep and contact dromedaries that were kept together with the inoculated camels remained virus-negative and did not seroconvert when tested up to 28 days post-inoculation (p.i.). In comparison with the non-susceptible dromedaries, the two inoculated Bactrian camels showed moderate to severe clinical signs of FMD; however, the clinical signs of FMD appeared rather late, between 8 and 14 days p.i., compared to the inoculated sheep. Characteristic FMD lesions in the Bactrian camels, accompanied with severe lameness, were only observed on the hind feet. The presence of the virus in the serum samples of both Bactrian camels was detected by real-time RT-PCR in one of the animals on days 3 and 7 p.i. and in the second animal from days 1 to 3 p.i. and subsequently again on day 21 p.i. The Bactrian camels developed high titres of antibodies to the inoculated FMDV which appeared at 7-10 days p.i. and lasted up to 130 days p.i. Only low and transient amounts of FMDV were detected in the mouth-swab and probang samples collected from both Bactrian camels.     

Vaccination of pigs two weeks before infection significantly reduces transmission of foot-and-mouth disease virus

The objective of this study was to investigate whether and at what time interval could vaccination reduce transmission of foot-and-mouth disease virus (FMDV) among pigs. Reduction of virus transmission by vaccination was determined experimentally. Transmission of FMDV was studied in three groups of ten pigs: one non-vaccinated group and two groups that were vaccinated 7 days (-7 dpi) and 14 days before inoculation (-14 dpi), respectively. Five randomly selected pigs from each group were inoculated with FMDV type O Taiwan, while the other five pigs left in the groups were exposed to the inoculated pigs by direct contact. Clinical signs were recorded, virus isolation and RT-PCR were carried out on oropharyngeal fluid (OPF), and the neutralizing antibody titres and the antibody response against non-structural (NS) proteins of FMDV were determined. No virus transmission was observed in the -14 dpi group, whereas virus transmission was observed in all contact pigs affecting both the non-vaccinated and the -7 dpi group. The reproduction ratio R in the -14 dpi vaccinated group was significantly lower than that of the non-vaccinated group. This study confirms the potential of vaccination as an important tool to reduce transmission of FMDV.     

Immunization with heterologous flaviviruses protective against fatal West Nile encephalitis

Prior immunization of hamsters with three heterologous flaviviruses (Japanese encephalitis virus [JEV] SA14-2-8 vaccine, wild-type St. Louis encephalitis virus [SLEV], and Yellow fever virus [YFV] 17D vaccine) reduces the severity of subsequent West Nile virus (WNV) infection. Groups of adult hamsters were immunized with each of the heterologous flaviviruses; approximately 30 days later, the animals were injected intraperitoneally with a virulent New York strain of WNV. Subsequent levels of viremia, antibody response, and deaths were compared with those in nonimmune (control) hamsters. Immunity to JEV and SLEV was protective against clinical encephalitis and death after challenge with WNV. The antibody response in the sequentially infected hamsters also illustrates the difficulty in making a serologic diagnosis of WNV infection in animals (or humans) with preexisting Flavivirus immunity.     

Pestivirus infections in ruminants in Norway.

Serological surveys in Norway have demonstrated neutralising antibodies against bovine virus diarrhoea (BVD) virus in cattle, sheep and goats. The prevalences were 18.5%, 4.5% and 3.6%, respectively. Occurrence of pestivirus-induced disease in Norway is described. Outbreaks of reproductive failure and mucosal disease have been reported, and the number of persistently-infected animals detected has increased considerably in recent years. Acute BVD occurs rarely. Border disease (BD) in sheep, first diagnosed in 1981, has subsequently been demonstrated sporadically. In goats, typical BD was diagnosed in 1982, with three later occurrences of reproductive failure. Experimental infections in pregnant goats induced a high rate of severe foetopathogenic effect. Signs and lesions in offspring were comparable to ovine BD. Similar findings were demonstrated in goats given a pestivirus-contaminated vaccine. In newborn kids, experimental infection had an adverse influence on growth and health. Persistent infection in goats is probably rare.     

Excretion of foot-and-mouth disease virus in oesophageal-pharyngeal fluid and milk of cattle after intranasal infection.

The virus growth in the pharyngeal area and the virus excretion in milk of susceptible and vaccinated dairy cows after intranasal instillation of foot-and-mouth disease (FMD) virus type O1 were examined. Ten vaccinated cows were purchased through a market. Of these, nine had delivered their first calf. The cows were inoculated 2-9 months after having received the last dose of vaccine. All vaccinated cows resisted the intranasal challenge. The virus multiplied in the pharyngeal area but, compared with two susceptible controls, to a limited extent. No clear relation was found between virus growth and the titre of circulating neutralizing antibody at the time of challenge. Virus was first detected in milk samples of the susceptible cows when generalized FMD lesions had developed on day four; the excretion lasted for 3-4 days. Up to 19 days after inoculation untreated milk of the vaccinated cows was examined for the presence of infectious FMD virus. Samples were inoculated onto cell cultures, fed to susceptible pigs and calves and injected intramuscularly and/or intradermolingually into susceptible steers. No infectious FMD virus could be detected, either in cell cultures or in susceptible animals. The animals did not develop neutralizing antibody against FMD virus and were subsequently shown to be fully susceptible to challenge. The results are discussed with particular reference to current problems regarding the export of milk products from countries where vaccination against FMD is practised to countries free of the disease.     

Experimental infection of sheep with a rabies virus of canine origin: study of the pathogenicity for that species]

The effects of the inoculation of a canine strain of rabies virus in sheep were studied using ten animals which received different amounts of this virus. Two subjects, inoculated with 10(5.4) mouse intracerebral lethal doses 50% (MICLD50), died from rabies after 19 and 40 days of incubation. Clinical signs were anorexia, emaciation, nervous reactions and prostration before death. The virus was recovered from different parts of the central nervous system and salivary glands with high titres. Only three animals showed an antibody response, at very low levels.     

Swine vesicular disease: pathways of infection.

The pathways of infection in swine vesicular disease have been studied by (i) an estimation of the amounts of virus required to produce infection by different artificial inoculation procedures; (ii) the distribution and amounts of virus in various tissues of pigs killed at intervals after contact infection; (iii) an investigation of the susceptibility to virus infection of pig tissue explants. The results show that pigs can be infected by a number of pathways and that the skin, as the most susceptible tissue, is probably the most frequent route of infection.     

Prevalence,distribution, and host range of Peste des petits ruminants virus,Turkey

Peste des petits ruminants virus (PPRV, genus Morbillivirus), which causes a severe disease in sheep and goats, has only recently been officially declared to be present in Turkey. We carried out a study to determine the prevalence, distribution, and host range of PPRV in Turkey. A total of 1,607 animals, reared in 18 different locations, were monitored for the presence of antibodies to PPRV and the related virus of large ruminants, Rinderpest virus (RPV). Only two farms had animals that were free of antibody responses to either disease. Prevalence for PPRV infection varied (range 0.87%-82.6%) and was higher in sheep (29.2%) than in goats (20%). The overall antibody responses to PPRV and RPV were 22.4% and 6.28%, respectively. Two PPRVs of lineage 4, which comprises many other PPRVs whose origins are in the Middle East, the Arabian Peninsula, and southern Asia, were isolated from Turkish sheep.     

An outbreak of Rift Valley fever in Northeastern Kenya, 1997-98

In December 1997, 170 hemorrhagic fever-associated deaths were reported in Garissa District, Kenya. Laboratory testing identified evidence of acute Rift Valley fever virus (RVFV). Of the 171 persons enrolled in a cross-sectional study, 31(18%) were anti-RVFV immunoglobulin (Ig) M positive. An age-adjusted IgM antibody prevalence of 14% was estimated for the district. We estimate approximately 27,500 infections occurred in Garissa District, making this the largest recorded outbreak of RVFV in East Africa. In multivariable analysis, contact with sheep body fluids and sheltering livestock in one s home were significantly associated with infection. Direct contact with animals, particularly contact with sheep body fluids, was the most important modifiable risk factor for RVFV infection. Public education during epizootics may reduce human illness and deaths associated with future outbreaks.     

Sero-epidemiological study of peste des petits ruminants in sheep and goats in India between 2003 and 2009

This study describes the serosurveillance of peste des petits ruminants (PPR) in sheep and goats that was carried out between 2003 and 2009 using serum samples from animals suspected of PPR that were submitted to the Rinderpest and Allied Disease Laboratory (Division of Virology of the Indian Veterinary Research Institute [IVRI]). A total of 2,197 serum samples from sheep and 2,687 from goats were screened for PPR virus (PPRV) antibody using a monoclonal antibody-based competitive enzyme-linked immunosorbent assay developed at IVRI. Screening of the 4,884 serum samples showed that the prevalence of PPRV antibody in sheep and goats was 41.01% (95% confidence interval [CI]: 31.86 to 50.16) and 46.11% (95% CI: 37.18 to 55.04), respectively, with an overall prevalence of 43.56% (95% CI: 36.78 to 50.34) during the period. This indicates increased and widespread infection with the virus in India compared with earlier reports, which is attributed to the variations in sheep and goat husbandry practices in different regions, the agro-climatic conditions, the topography of different states, the socio-economic status of individual farmers and the migration of livestock in India.     

Enhancement of protective antibody responses by cholera toxin B subunit inoculated intranasally with influenza vaccine

Effects of the B subunit of cholera toxin (CTB) on the primary antibody responses to influenza virus A/PR/8/34 (PR-8) (H1N1) HA vaccine and on protection against viral challenge were investigated in Balb/c mice which were immunized intranasally with both the vaccine and CTB. The dose of CTB (greater than or equal to 1 microgram) inoculated with the vaccine (greater than or equal to 0.15 microgram) induced high responses of both antiviral IgA antibodies in the nasal wash and haemagglutinin-inhibiting (HI) antibody in the serum, enough to provide complete protection against viral challenge four weeks after immunization. High levels of antibody were maintained for more than 16 weeks after inoculation, affording complete protection during this interval. The inoculation of HA vaccine prepared from influenza viruses A/Yamagata/120/86 (H1N1) or A/Fukuoka/C29/85 (H3N2) together with CTB provided partial protection against PR-8 infection, with production of antiviral IgA antibodies which were cross-reactive to PR-8 antigens whereas immunization with CTB and HA vaccine prepared from a different type of influenza virus (B/Ibaraki/2/85) failed to protect against PR-8 infection. These results indicate that CTB can produce an augmented and persistent antibody response to PR-8 HA vaccine, which is cross-protective to other A-type virus infections. The mechanisms by which CTB enhances the protective antibody responses to the nasally inoculated vaccine were investigated. The ability of CTB to augment antibody responses was lost, either when CTB was inoculated via the intravenous or subcutaneous route, or when CTB was introduced into nasal site one day before or after the vaccine inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Experimental infection of castrated lambs with Mycoplasma agalactiae.

The course of experimental infection in groups of 6-month-old castrated lambs with field isolates of Mycoplasma agalactiae from France was followed culturally and serologically for 7 months. Infection with an ovine field isolate following inoculation by different routes and contact exposure was compared with that caused similarly by a caprine field isolate. The prolonged infections produced were symptomless apart from limited arthritis in one animal inoculated with the isolate from sheep and increased lachrymation in another associated with the goat isolate. The ovine isolate was more virulent in that ante- and post-mortem recoveries of the organism were more consistent and the serological responses more pronounced. Serological responses varied between animals and between strain infections, and the results of the film inhibition test were more consistent than those of the complement fixation test. The limitations of both these tests for detecting carrier infections are discussed.     

Experimental infection of castrated lambs with Mycoplasma agalactiae

The course of experimental infection in groups of 6-month-old castrated lambs with field isolates of Mycoplasma agalactiae from France was followed culturally and serologically for 7 months. Infection with an ovine field isolate following inoculation by different routes and contact exposure was compared with that caused similarly by a caprine field isolate. The prolonged infections produced were symptomless apart from limited arthritis in one animal inoculated with the isolate from sheep and increased lachrymation in another associated with the goat isolate. The ovine isolate was more virulent in that ante- and post-mortem recoveries of the organism were more consistent and the serological responses more pronounced. Serological responses varied between animals and between strain infections, and the results of the film inhibition test were more consistent than those of the complement fixation test. The limitations of both these tests for detecting carrier infections are discussed.