Sex differences in verbal and visual-spatial tasks under different hemispheric visual-field presentation conditions.

This paper reports sex differences in cognitive task performance that emerged when 39 Australian university undergraduates (19 men, 20 women) were asked to solve verbal (lexical) and visual-spatial cognitive matching tasks which varied in difficulty and visual field of presentation. Sex significantly interacted with task type, task difficulty, laterality, and changes in performance across trials. The results revealed that the significant individual-differences' variable of sex does not always emerge as a significant main effect, but instead in terms of significant interactions with other variables manipulated experimentally. Our results show that sex differences must be taken into account when conducting experiments into human cognitive-task performance.

A morbillivirus that caused fatal disease in horses and humans.

A morbillivirus has been isolated and added to an increasing list of emerging viral diseases. This virus caused an outbreak of fatal respiratory disease in horses and humans. Genetic analyses show it to be only distantly related to the classic morbilliviruses rinderpest, measles, and canine distemper. When seen by electron microscopy, viruses had 10- and 18-nanometer surface projections that gave them a "double-fringed" appearance. The virus induced syncytia that developed in the endothelium of blood vessels, particularly the lungs.

Empathy-related responses to moving film stimuli depicting human and non-human animal targets in negative circumstances.

Research supports an "ingroup empathy hypothesis" of higher empathy-related psychophysiological responses towards individuals of the same ethnicity. However, little research has investigated empathy-related responses to non-human targets graded for phylogenetic relatedness. Participants (N=73) were presented with film stimuli depicting humans, primates, quadruped mammals and birds in victimized circumstances. Phasic skin conductance responses (SCR) and subjective empathy-related ratings to the film clips increased as phylogenetic similarity to humans increased across animal groups, revealing an empathic bias towards human stimuli. Participants also completed a trait empathy scale. High trait empathy participants gave higher subjective empathy ratings than moderate and low trait empathy participants. Low trait empathy participants showed less corrugator electromyographic activity than moderate and high empathy participants. The moderate trait empathy participants showed higher SCR than the high group. The results confirm an effect of phylogenetic similarity in subjective self-report and psychophysiological measures of empathy-related responses. Additionally, convergence between subjective and objective measures of empathy-related responses was observed.

Foot and mouth disease in the Lao People's Democratic Republic: II. Seroprevalence estimates, using structured surveillance and surveys of abattoirs.

An examination of the seroprevalence of foot and mouth disease (FMD) virus was conducted in the Lao People's Democratic Republic (Lao PDR) from 1996 to 2005, using structured surveillance and abattoir-based studies. Under structured surveillance, seropositivity ranged from 65.7% (Vientiane Capital, 1996) to 3% (Houaphan, 2005) for cattle and buffalo; and from 2.8% (Vientiane Capital, 1998) to 0% in separate studies of pigs. In each study, species composition was significantly associated with seroprevalence rates. For abattoir surveys, the majority of samples (60.5%) came from Vientiane Capital (33.0%), Savannakhet (14.0%) and Champasak (13.5%) provinces. The overall proportion of animals testing positive for the presence of antibodies against the FMD virus was 18.7% (ranging from 50.8% in Vientiane Province to 1% in Phongsali). Generally, antibodies against serotype O were the most prevalent. Cattle and buffalo that tested as seropositive were significantly older than the seronegative animals (p < 0.00005). The overall proportional seropositivity was significantly different for different species, as was the case with the antibodies against serotypes O, A and Asia 1. Some 22% of cattle, 55% of buffalo and 23% of pigs demonstrated seropositivity but this varied significantly between provinces.

Foot and mouth disease in the Lao People's Democratic Republic: I. A review of recent outbreaks and lessons from control programmes.

Foot and mouth disease (FMD) causes sporadic disease outbreaks in the Lao People's Democratic Republic (Lao PDR). As the Lao PDR is a major thoroughfare for transboundary animal movements, regular FMD outbreaks occur, causing economic hardship for farmers and their families. In this review of the recent history of FMD in the Lao PDR between 1997 and 2006, the authors examine the virological and epidemiological aspects of the disease and appropriate control measures, including the distribution of outbreaks, causative serotypes and the molecular epidemiology of the viruses, as well as large-scale vaccination programmes. The dominant serotype, type O, was reported every year from 1998 to 2005. The majority of outbreaks occurred in Vientiane Capital (n = 42; 28%) and the highest number of outbreaks were reported in cattle (n = 94; 61%); followed by buffalo (n = 41; 27%) and pigs (n = 18; 12%). All type A outbreaks occurred in cattle. Type Asia 1 outbreaks were reported in the central provinces around Vientiane Capital between 1996 and 1998.

Experimental Nipah virus infection in pteropid bats (Pteropus poliocephalus).

Seventeen grey-headed fruit bats (Pteropus poliocephalus) were inoculated subcutaneously with an isolate of Nipah virus derived from a fatally infected human. A control group of eight guinea-pigs was inoculated intraperitoneally with the same isolate in order to confirm virulence. Three of eight infected guinea-pigs developed clinical signs 7-9 days post-inoculation. Infected fruit bats developed a subclinical infection characterized by the transient presence of virus within selected viscera, episodic viral excretion and seroconversion. A range of histopathological changes was observed within the tissues of infected bats. Nipah virus was excreted in bat urine while neutralizing antibody was present in serum. This intermittent, low-level excretion of Nipah virus in the urine of bats may be sufficient to sustain the net reproductive value of the virus in a species where there is regular urine contamination of the fur, mutual grooming, and where urine droplets are a feature of the environment.

High level expression of the envelope glycoprotein (gp53) of bovine viral diarrhoea virus (Singer) and its potential use as diagnostic reagent.

A 1.74-kb cDNA fragment containing the gp53 coding region has been cloned from bovine viral diarrhoea virus (BVDV) strain Singer by reverse transcription polymerase chain reaction (RT-PCR). Sequence analysis indicated that gp53 of BVDV strains Singer, NADL and SD-1 shared extensive sequence homology at both the RNA (85-94%) and protein (82-91%) levels. Nineteen cysteine residues and five potential N-linked glycosylation sites were identified within the sequenced region, all of which were conserved. These observations suggest that although the homology at the nucleotide sequence level may vary, there was strong structural conservation among bovine viral diarrhoea virus envelope proteins. Full-length gp53 was expressed in Escherichia coli as a fusion protein with glutathione-S-transferase (GST). The N-terminal half of gp53 was also synthesised in E. coli as a 28-KDa recombinant protein using the T7 RNA polymerase-directed expression system. Both recombinant proteins were expressed at high levels (approximately 30-50 mg/l). The recombinant proteins were recognised in ELISA and Western blot analyses by polyclonal serum raised against a mixture of BVDV and classical swine fever virus (CSFV). Rabbit antiserum raised against the 28-kDa recombinant protein reacted with different BVDV strains in ELISA and immunofluorescent antibody test, but not with CSFV in the same tests. These results demonstrated that the bacterial recombinant proteins have similar immunological properties to that of the native viral protein and, in conjunction with its homologous antisera, can be useful as diagnostic reagents.

Virulent Newcastle disease in Australia: molecular epidemiological analysis of viruses isolated prior to and during the outbreaks of 1998-2000.

Gene sequence analysis of fusion (F) gene cleavage motifs and haemagglutinin-neuraminidase (HN) carboxyl-terminal extension sequences was used to analyse Newcastle disease viruses (NDV) associated with virulent outbreaks of the disease which occurred in New South Wales, Australia in 1998-2000. PCR fragments were amplified directly from diseased tissue or allantoic fluids and sequence analyses used for phylogenetic comparisons between these viruses and Australian reference NDV. F and HN gene sequence comparison showed a strong relationship to sequences derived from endemic Australian NDV rather than those of overseas viruses or wild bird isolates. Prior to notification of the 1998 outbreak, an NDV was isolated from chickens suffering respiratory disease that appeared to be the progenitor virus from which the virulent virus originated. In turn, these viruses are closely related to two previously isolated 'ancestor' viruses that have the same unique HN extension sequence.

The complete nucleotide sequence of rabbit haemorrhagic disease virus (Czech strain V351): use of the polymerase chain reaction to detect replication in Australian vertebrates and analysis of viral population sequence variation.

The complete nucleotide sequence of the Czech strain of rabbit haemorrhagic disease virus (RHDV) was determined to be 7437 nucleotides in length with a 5-terminal non-coding region of 9 nucleotides and a 3'-terminal non-coding region of 59 nucleotides. Two open reading frames (ORFs) were found within this sequence coding for polypeptides of 2344 (nucleotides 10-7044) and 117 amino acids (nucleotides 7025-7378). The sequence of this isolate was approximately 1% different from that reported by Meyers et al., having 78 nucleotide changes which resulted in 30 amino acid differences, the majority of these clustering in the N-terminus of the large ORF and the middle of the viral coat protein. Only a single conservative amino acid change was seen in the smaller 3'-terminal ORF. Since the virus cannot at present be propagated in tissue culture, but isolated only after replication in rabbits, the reported sequence must be considered as a consensus sequence from the viral population. To gain some understanding of the possible sequence diversity within this virus population, 97 clones were sequenced from a polymerase chain reaction (PCR) fragment to determine the sequence diversity of the virus population. Four major classes of variant were described with mutations generally in the third base position of codons. A nested reverse transcriptase (RT) PCR (using sequence derived for the coat protein of RHDV) was used to determine the presence or absence of RHDV inoculated into non-host animal species. No replication of the virus was detected in 28 different vertebrate species other than rabbits. PCR tests on both mosquitoes and fleas feeding on RHDV infected rabbits were positive. The RT-PCR test was more sensitive when compared with an antigen capture ELISA to detect the presence of genomic RNA/or virus in infected rabbits.

Presence of rabbit haemorrhagic disease virus antigen in rabbit tissues as revealed by a monoclonal antibody dependent capture ELISA.

The production of monoclonal antibodies (mAbs) to a common antigenic region on rabbit haemorrhagic disease virus (RHDV) has enabled the development of a capture ELISA for virus detection. The assay was shown to detect reliably the presence of viral antigen in crude homogenates of a range of rabbit tissues and has provided the first evidence for the presence of RHDV in blood, serum and heart tissue. A limited time course study of the progression of virus infection revealed viral antigen is first detected in the liver at between 18 and 24 h post-infection (p.i.) and in the spleen between 24 and 30 h p.i. The assay displayed a high level of specificity, clearly differentiating between groups of infected (lowest observed optical density (O.D.) 0.45) and uninfected (highest O.D. 0.06) rabbits. No viral antigen was detected in the urine or faeces collected from infected rabbits at post-mortem. Experiments employing the 'spiking' of pools of urine and faecal homogenates collected from uninfected rabbits, with a known amount of virus, indicated that RHDV may not be present in the faeces of infected animals and if present in urine, it appears to undergo substantial degradation.

Newcastle disease virus: an evolving pathogen?

Australia experienced outbreaks of virulent Newcastle disease (ND) in chickens in the state of New South Wales in the years 1998, 1999 and 2000. The disease had occurred previously in Australia in 1930 and 1932 but the country was free of it until the recent outbreaks. Avirulent strains of Newcastle disease virus (NDV) were detected in 1966 and, during the next two to three decades, strains (so-called lentogenic strains) able to induce mild respiratory disease equivalent to that induced by vaccine strains such as LaSota were also detected. Nucleotide sequence analysis of the genes encoding the haemagglutinin and fusion proteins of Australian isolates of the virus during this time demonstrated that Australian chicken strains of NDV could be differentiated from NDV isolated elsewhere. Analysis in this way demonstrated that NDV isolates causing the recent outbreaks of virulent disease were Australian viruses that were so closely related to a recognized Australian lentogenic strain, termed the Peat's Ridge strain, that it was considered to be the precursor of the virulent virus. The outbreaks of virulent disease in 1998 and 1999 were controlled by an official "stamping out" eradication campaign. This was subsequently replaced by strategic use of ND vaccines when virulent virus was again detected on some farms that had been restocked following depopulation. The national situation with regard to ND is now being assessed through a structured national survey of ND viruses, particularly to determine the distribution of the precursor strain. No new outbreaks of virulent ND have been recognized since February 2000, although immunization of flocks in areas where the disease was recognized has occurred.

Single dilution ELISA for detection of serum antibody to foot-and-mouth disease virus in cattle.

A single dilution blocking ELISA was developed and evaluated for measuring serum antibody to foot-and-mouth disease virus (FMDV). Basic parameters of the assay were established and a positive-negative threshold determined from testing 176 specific antibody negative sera from Australian cattle. Sera collected from immunised animals in Thailand were tested by ELISA and virus-neutralisation (VN) tests and the results compared. A positive correlation between ELISA and VN titres was recorded for each of the 3 FMDV serotypes endemic in Thailand, with the overall correlation coefficient being r = 0.8990. A positive correlation for each of the serotypes was also found between ELISA titre and the degree of blocking (percentage inhibition) of each test serum at a dilution of 1:16, with the overall correlation being r = 0.8704. This simplified ELISA was sensitive, specific and gave reproducible results, and had the potential to test quickly and efficiently a considerable number of sera.

Detection of hog cholera virus antigens in experimentally-infected pigs using an antigen-capture ELISA.

An antigen-capture ELISA was used to detect hog cholera virus (HCV) antigens in blood and tissues taken from pigs infected with 2 different strains of virus. Specific antigens were demonstrated in peripheral blood leucocytes (PBLs) and a wide range of tissue samples 4-6 days after infection of pigs with a moderate-high virulent HCV strain (Weybridge virus). Strong signal to noise (S/N) ratios were obtained in the ELISA for PBLs and lymphoid tissues such as spleen, tonsil and mesenteric lymph nodes at 5-7 days after infection with the Weybridge virus, S/N ratios varying between 8.1-19.7 for blood samples and 4.3-19.1 for spleen samples. High positive ELISA results were also obtained for duodenum and ileum samples (S/N ratios 10.3-18.6) taken from these pigs, reflecting severe pathological changes observed in the gut at post mortem. In contrast, the antigen-capture ELISA gave strong positive results for PBLs and spleen samples only at 7-9 days after infection of pigs with a low virulent strain of HCV (New South Wales virus). The ELISA S/N ratios averaged 9.5 for PBLs and 8.9 for spleen samples in these animals. Although virus isolation detected infection earlier in the infected pigs, the ELISA returned positive results on PBLs and spleen samples around the time all of the animals first showed typical signs of classical swine fever. The technique does not require tissue culture and takes less than 36 h to return a definitive result.

A comparison of enzyme-linked immunosorbent assay, complement fixation and virus isolation for foot and mouth disease diagnosis.

A total of 205 epithelial tissue samples were examined for the presence of foot and mouth disease virus by either the complement-fixation (CF) test, enzyme-linked immunosorbent assay (ELISA) and/or by virus isolation in bovine thyroid or kidney cell cultures. The virus was isolated from 134 of the 201 (67%) specimens. Samples, from which virus was isolated, were termed virus-positive samples. The CF test detected viral antigen in 30 (24%) of 123 virus-positive samples, whereas the ELISA detected it in 100 (81%) of these specimens. The ELISA was thus at least 3 times more efficient than the CF test in detecting the virus in epithelial-tissue samples. There were 5 samples from which virus was not isolated but which were positive with the ELISA procedure. The ELISA was particularly useful for testing samples from pigs and for assessing specimens from animals with resolving lesions. The ELISA gave virus type-specific results in 89% of 63 virus-positive cases compared to 40% for the CF test. The ELISA was thus a very useful, accurate and sensitive method for the direct testing of epithelial tissues of affected animals.

Development of a polymerase chain reaction to detect Vietnamese isolates of duck virus enteritis.

A polymerase chain reaction (PCR) method for the detection of duck virus enteritis (DVE) virus in tissues of infected and affected ducks, and in cell culture was developed. This required us to obtain specific nucleotide sequence information as we could not find any specific data about the genome of the virus. We found the assay to be highly effective in detecting the virus under experimental conditions and to be easily transferred to laboratories in Vietnam where it is being used in studies on the epidemiology of the disease. We have applied this simple and rapid diagnostic method to the detection of DVE isolates grown in cell culture and tissues from infected birds. The assay was also able to differentiate DVE from other avian herpesviruses, such as Marek's disease, infectious laryngotracheitis virus and goose herpesvirus.

A competition ELISA for the detection of antibodies to rabbit haemorrhagic disease virus.

Monoclonal antibodies (mAbs) were raised to a preparation of rabbit haemorrhagic disease virus (RHDV) purified from the livers of experimentally infected rabbits. Rabbit antisera to RHDV significantly blocked the binding of two mAbs (2D3(3) and 2D4(5)) to RHDV-coated microplate wells in a competition ELISA. The virus-specific nature of these mAbs was confirmed by immunoperoxidase and immunofluorescence assays on formalin-fixed and fresh infected liver tissue. Utilization of one of these mAbs (2D3(3)) in a competition ELISA, resulted in an RHDV antibody assay which proved more specific than an indirect ELISA and more rapid and reliable than a haemagglutination inhibition assay for screening serum samples from wild and experimental rabbits.

Implementation of internal laboratory quality control procedures for the monitoring of ELISA performance at a regional veterinary laboratory.

Quality control (QC) procedures for antigen detection enzyme-linked immunosorbent assays (ELISAs) for hog cholera (HC) virus, foot and mouth disease (FMD) virus, and an antibody detection ELISA for FMD virus were established at a regional veterinary laboratory in northern Thailand. A recently developed computer software package, QCEL, was used to facilitate management and analysis of QC data. The program was used to assess test performance by producing Shewhart-CUSUM control charts which monitored control data for unacceptable fluctuations or trends. QCEL-generated control charts and analyses are presented and discussed. The use of a simple integrated computerised system for storage and analysis of QC control data provided the laboratory with the opportunity to achieve increased confidence in the results of tests performed.

Visual versus computerised assessment of left ventricular function from cinéangiography.

Visual assessment of left ventricular function from cinéangiography was compared with computerised assessment in 48 randomly selected cinéangiograms. The parameters compared included end-diastolic volume, end-systolic volume, stroke volume, ejection fraction and left ventricular output. There was poor agreement between visual and calculated values for end-diastolic volume, stroke volume and left ventricular output, but good agreement for ejection fraction and moderately good agreement for end-systolic volumes. Absolute values are particularly difficult to assess.

Newcastle disease virus--some properties of Australian strains.

Seventeen Australian strains of Newcastle disease virus were tested for their biological properties: mean death time, heat stability of the hemagglutinin and infectivity of the virus at 56 C, the elution time of virus from chicken erythrocytes, and the ability to hemagglutinate equine red blood cells. The strains differed considerably in their reactions. All had mean-death-time indices of 112 or greater, indicating that all were lentogenic. Strains were identified that had heat-labile and -stable hemagglutinin and infectivity, slow and fast elution, and variable ability to agglutinate equine erythrocytes. The significance of the results is discussed in terms of their usefulness in identifying exotic strains of the virus.

Virological studies of Adelie Penguins (Pygoscelis adeliae) in Antarctica.

Serum antibodies to influenza virus hemagglutinin 7, Newcastle disease virus (NDV), and avian paramyxoviruses were detected in Adelie penguin colonies in Antarctica. Infection with NDV and avian influenza virus was confined to particular colonies, whereas antibodies to the paramyxoviruses were detected in all seven colonies samples. Two avian paramyxoviruses were also isolated fromcloacal swabs. Results of serological tests must be interpreted with caution, as little as known about the persistence of specific antibodies in Adelie penguins.