scholarly journals Modelling the time-dependent transmission rate for porcine circovirus type 2 (PCV2) in pigs using data from serial transmission experiments

2008 ◽  
Vol 6 (30) ◽  
pp. 39-50 ◽  
Author(s):  
M Andraud ◽  
B Grasland ◽  
B Durand ◽  
R Cariolet ◽  
A Jestin ◽  
...  
Keyword(s):  
Transmission Rate ◽  
Transmission Function ◽  
Latency Period ◽  
Porcine Circovirus Type ◽  
Time Dependent ◽  
Porcine Circovirus ◽  
Infectious Period ◽  
Post Inoculation ◽  
Unimodal Function ◽  
Reproduction Ratio

Six successive transmission trials were carried out from 4 to 39 days post inoculation (DPI) to determine the features of the infectious period for PCV2-infected pigs. The infectiousness of inoculated pigs, assessed from the frequency of occurrence of infected pigs in susceptible groups in each contact trial, increased from 4 to 18 DPI (0, 7 and 8 infected pigs at 4, 11 and 18 DPI, respectively) and then decreased slowly until 39 days post infection (4, 2 and 1 pigs infected at 25, 32 and 39 DPI, respectively). The estimated time-dependent infectiousness was fitted to three unimodal function shapes (gamma, Weibull and lognormal) for comparison. The absence of infected pigs at 4 DPI revealed a latency period between 4 and 10 DPI. A sensitivity analysis was performed to test whether the parametric shape of the transmission function influenced the estimations. The estimated time-dependent transmission rate was implemented in a deterministic SEIR model and validated by comparing the model prediction with external data. The lognormal-like function shape evidenced the best quality of fit, leading to a latency period of 8 days, an estimated basic reproduction ratio of 5.9 [1.8,10.1] and a mean disease generation time of 18.4 days [18.2, 18.5].

scholarly journals Differences in virulence among porcine circovirus type 2 isolates are unrelated to cluster type 2a or 2b and prior infection provides heterologous protection

2008 ◽  
Vol 89 (10) ◽  
pp. 2482-2491 ◽  
Author(s):  
T. Opriessnig ◽  
S. Ramamoorthy ◽  
D. M. Madson ◽  
A. R. Patterson ◽  
N. Pal ◽  
...  
Keyword(s):  
Porcine Circovirus Type ◽  
Porcine Circovirus Type 2 ◽  
Cross Protection ◽  
Porcine Circovirus ◽  
Post Inoculation ◽  
Treatment Groups ◽  
Associated Lesions ◽  
Specific Pathogen ◽  
Genetic Clusters

Porcine circovirus type 2 (PCV2) is divided into two genetic clusters designated PCV2a and PCV2b. The objectives of this study were to determine whether isolates from different clusters vary in virulence and to determine whether infection with PCV2a isolates induces protective immunity against subsequent infection with a recent PCV2b isolate. One-hundred and thirteen conventional specific-pathogen-free (SPF) pigs were assigned randomly to treatment groups and rooms: pigs inoculated with PCV2a cluster isolates (ISU-40895 or ISU-4838), pigs inoculated with PCV2b cluster isolates (NC-16845 or Can-17639) and uninoculated pigs. Necropsies were performed at 16 or 51 days post-inoculation (p.i.). There were no significant differences in PCV2-associated lymphoid lesions between PCV2a and PCV2b clusters; however, within the same cluster, significant differences were found between isolates: ISU-4838- and Can-17639-inoculated pigs had significantly (P<0.05) less severe lesions compared with ISU-40895- and NC-16845-inoculated pigs. To evaluate cross-protection, six pigs within each group were challenged at 35 days p.i. with an isolate from the heterologous cluster and were necropsied 51 days p.i. The severity of PCV2-associated lesions was reduced in pigs with prior exposure to an isolate from the heterologous cluster in comparison with singly inoculated pigs. Results indicate that the virulence of PCV2a and PCV2b isolates is not different in the conventional SPF pig model; however, the virulence of isolates within the same cluster differs. Increased virulence as reported to be associated with PCV2b isolates in the field was not observed under the conditions of this study. Moreover, cross-protection between PCV2a and PCV2b exists.

Transmission of porcine circovirus type 2b (PCV2b) in Kunming mice

2013 ◽  
Vol 61 (2) ◽  
pp. 234-243 ◽  
Author(s):  
Zhi Deng ◽  
An Yuan ◽  
Wei Luo ◽  
Nai Wang ◽  
Qian Gong ◽  
...  
Keyword(s):  
Viral Antigen ◽  
Transmission Rate ◽  
Porcine Circovirus Type ◽  
High Ratio ◽  
Porcine Circovirus ◽  
Chain Reaction ◽  
Newborn Mice ◽  
Outbred Mouse ◽  
Pregnant Mice ◽  
Polymerase Chain

To investigate porcine circovirus type 2b (PCV2b) transmission by contact and vertical infection in Kunming mice (an outbred mouse stock deriving from Swiss albino mice with a high ratio of gene heterozygosis), four mice in cage 6 were inoculated with PCV2b and 25 mice without any treatment were placed into cages 1 to 5 (five mice in each cage). Seven days after being infected, the PCV2-binoculated mice were co-mingled with non-inoculated mice from cages 1 to 5 successively at 7, 14, 21, 28 and 35 days post infection (dpi), respectively, for 3 days. In addition, eleven pregnant mice were injected with PCV2b. Samples were collected from non-inoculated mice and three newborn mice from each litter for PCV2b detection by polymerase chain reaction (PCR) and immunohistochemistry (IHC). The PCR results showed that PCV2b transmission rate among mice in cages 1, 2, 3, 4 and 5 was 0/5, 2/5, 5/5, 5/5 and 1/5, respectively. PCV2b antigen signals generally appeared in most organs of the non-inoculated mice in which viruses were detected by PCR. PCV2b DNA was also detected in newborn mice of PCV2b-infected litters, and viral antigen signals were observed in their organs as well. PCV2b was transmitted in Kunming mice by contact, and it also caused vertical infection through the placenta.

Replication and transmission of porcine circovirus type 2 in mice

2008 ◽  
Vol 56 (3) ◽  
pp. 421-427 ◽  
Author(s):  
Attila Cságola ◽  
Daniel Cadar ◽  
Tamás Tuboly
Keyword(s):  
Animal Experiments ◽  
Porcine Circovirus Type ◽  
Virus Genome ◽  
Oral Route ◽  
Porcine Circovirus Type 2 ◽  
Porcine Circovirus ◽  
Post Inoculation ◽  
Group A ◽  
Group B

Little information is known about infection, replication and transmission of porcine circovirus type 2 (PCV2) in species other than swine. Two sets of animal experiments were carried out to investigate the susceptibility of mice to PCV2 and to study their possible role in maintaining and transmitting the virus. In the first experiment 14 mice were inoculated with PCV2 by the intraperitoneal route with 5 × 10 2 TCID 50 of the PCV2-ROM strain (Cadar et al., 2007). In a second experiment 24 mice were divided into two groups (A and B); mice in Group A (n = 18) were inoculated orally with 1 × 10 5 TCID 50 PCV2-ROM and mice in Group B (n = 6) were left uninoculated until day 12 post inoculation (p.i.), when they were mixed with Group A. The animals were sacrificed at intervals for postmortem investigation and virus genome detection by polymerase chain reaction (PCR). The PCR results indicated that PCV2 could replicate in mice infected intraperitoneally or by the oral route, and that the virus can be transmitted directly from mouse to mouse.

scholarly journals Forecasting Transmission Dynamics of COVID-19 Epidemic in India under Various Containment Measures- A Time-Dependent State-Space SIR Approach

2020 ◽  
Author(s):  
Vishal Deo ◽  
Anuradha Rajkonwar Chetiya ◽  
Barnali Deka ◽  
Gurprit Grover
Keyword(s):  
State Space ◽  
Transmission Rate ◽  
Sir Model ◽  
Primary Objective ◽  
Time Dependent ◽  
Infectious Period ◽  
Total Incidence ◽  
Comparison Results ◽  
Containment Measures ◽  
The Impact

Objectives Our primary objective is to predict the dynamics of COVID-19 epidemic in India while adjusting for the effects of various progressively implemented containment measures. Apart from forecasting the major turning points and parameters associated with the epidemic, we intend to provide an epidemiological assessment of the impact of these containment measures in India. Methods We propose a method based on time-series SIR model to estimate time-dependent modifiers for transmission rate of the infection. These modifiers are used in state-space SIR model to estimate reproduction number R0, expected total incidence, and to forecast the daily prevalence till the end of the epidemic. We consider four different scenarios, two based on current developments and two based on hypothetical situations for the purpose of comparison. Results Assuming gradual relaxation in lockdown post 17 May 2020, we expect the prevalence of infecteds to cross 9 million, with at least 1 million severe cases, around the end of October 2020. For the same case, estimates of R0 for the phases no-intervention, partial-lockdown and lockdown are 4.46 (7.1), 1.47 (2.33), and 0.817 (1.29) respectively, assuming 14-day (24-day) infectious period. Conclusions Estimated modifiers give consistent estimates of unadjusted R0 across different scenarios, demonstrating precision. Results corroborate the effectiveness of lockdown measures in substantially reducing R0. Also, predictions are highly sensitive towards estimate of infectious period.

Immunoenhancement of Recombinant Neisseria meningitides PorB Protein on Porcine Circovirus Type 2 and Mycoplasma hyopneumoniae Genetically Engineered Vaccines

2019 ◽  
Vol 26 (10) ◽  
pp. 776-784
Author(s):  
Rui Yang ◽  
Yu Tao ◽  
Gaojian Li ◽  
Jian Chen ◽  
Jianhong Shu ◽  
...  
Keyword(s):  
Recombinant Protein ◽  
Mycoplasma Hyopneumoniae ◽  
Porcine Circovirus Type ◽  
Porcine Circovirus Type 2 ◽  
Genetically Engineered ◽  
Porcine Circovirus ◽  
Practical Applications ◽  
Neisseria Meningitides ◽  
Short Period

Background:Porcine circovirus and Mycoplasma hyopneumoniae can cause respiratory diseases in pigs, which cause serious economic loss in the worldwide pig industry. Currently, these infections are mainly prevented and controlled by vaccination. The new vaccines on the market are mainly composed of subunits and inactivated vaccines but usually have lower antigenicity than traditional live vaccines. Thus, there is an increasing need to develop new adjuvants that can cause rapid and long-lasting immunity to enhance the antigenic efficacy for vaccines. Studies have shown that meningococcal porin PorB can act as a ligand to combine with Toll-like receptors to activate the production of immunological projections and act as a vaccine immunological adjuvant.Objective:In this article, we expressed and purified the recombinant PorB protein and verified its immunogenicity against porcine circovirus type 2 and Mycoplasma hyopneumoniae genetically engineered vaccine.Methods:In this article, we used prokaryotic expression to express and purify recombinant PorB protein, four different concentrations of PorB protein, Freund's adjuvant with two genetically engineered vaccines were combined with subcutaneous immunization of mice.Results:Our study shows that the appropriate dose of the recombinant protein PorB can enhance the levels of humoral and cellular responses induced by two genetically engineered vaccines in a short period of time in mice. The PorB adjuvant group may cause statistically higher antibody titers for both genetically engineered vaccines compared to Freund's commercial adjuvant (P<0.001).Conclusion:The recombinant protein PorB may be a good candidate adjuvant for improving the protective effect of vaccines against porcine circovirus type 2 and Mycoplasma hyopneumoniae, and the protein can be used for future practical applications.

scholarly journals Fractional SIR-Model for Estimating Transmission Dynamics of COVID-19 in India

J ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 86-100
Author(s):  
Nita H. Shah ◽  
Ankush H. Suthar ◽  
Ekta N. Jayswal ◽  
Ankit Sikarwar
Keyword(s):  
Basic Reproduction Number ◽  
Reproduction Number ◽  
Transmission Rate ◽  
Sir Model ◽  
Time Dependent ◽  
Contact Rate ◽  
Distribution Maps ◽  
Fundamental Parameters ◽  
Different Order ◽  
The Basic Reproduction Number

In this article, a time-dependent susceptible-infected-recovered (SIR) model is constructed to investigate the transmission rate of COVID-19 in various regions of India. The model included the fundamental parameters on which the transmission rate of the infection is dependent, like the population density, contact rate, recovery rate, and intensity of the infection in the respective region. Looking at the great diversity in different geographic locations in India, we determined to calculate the basic reproduction number for all Indian districts based on the COVID-19 data till 7 July 2020. By preparing district-wise spatial distribution maps with the help of ArcGIS 10.2, the model was employed to show the effect of complete lockdown on the transmission rate of the COVID-19 infection in Indian districts. Moreover, with the model's transformation to the fractional ordered dynamical system, we found that the nature of the proposed SIR model is different for the different order of the systems. The sensitivity analysis of the basic reproduction number is done graphically which forecasts the change in the transmission rate of COVID-19 infection with change in different parameters. In the numerical simulation section, oscillations and variations in the model compartments are shown for two different situations, with and without lockdown.

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