Pestivírus de bovinos (BVDV):

epidemiologia e genética molecular

Cláudio Wageck Canal Laboratório de Virologia

Universidade Federal do Rio Grande do Sul

ssRNA

~12.5 Kb

Enveloped

Classification and nomenclature

Virus Taxonomy Family: Flaviviridae

Genus: Pestivirus

Flaviviridae Family

Pestivirus genus

Classical swine fever virus

Border disease virus

Bovine viral diarrhea virus

Pestivirus genus 17 subtypes: BVDV-1a to BVDV-1q

03 subtypes: BVDV-2a to BVDV-2c

Infection in cattle

Acute infection

• Generally are subclinical;

• Clinical:

• Diarrhea,

• Fever,

• Leukopenia,

• Ocular/nasal discharge,

• Abortion

• Cleared within 14 to 21 days.

Persistent infection

• Retarded growth, congenital defects or appear

normal;

• Excrete virus throughout their lives

(spreading the infection in or between herds);

• Die in the first two years of life from MD or

secondary infections (consequence of virus-

induced immune depression)

By: José Bangel Júnior

The control of the foot and mouth disease was the main focus of

the Federal Veterinary Office during years

Diseases caused by pestiviruses and herpesviruses in cattle will

become one of the major virus disease targeted for controlling

due to (re)production performance loses in cattle herds

Several reports shown the presence of BVDV infection in Brazil

since the late 60s

Serological studies showed wide distribution of infection:

22-67% of the animals

43-90% of the herds

Introduction

Biosecurity

Vaccination

Surveillance

Decreased

Losses Due to

BVDV Infection

Reduces risk off exposure

Increased

Resistance

to BVDV

at herd level

Removal of PI

Why is important the knowledge about the circulating

species, genotypes or subgenotypes?

Establishment of correct diagnostic tools and control programs

Reports of failure of commonly used detection techniques

Significant antigenic variations in species and genotype/subgenotype levels demonstrated by differences in cross-neutralization tests using sera from immunized cattle

Vaccines in Brazil: underused

Only inactivated vaccines licensed

Strains of BVDV-1a and BVDV-2a

8 commercial vaccines tested

BVDV-1: 4 induced partial seroconversion

BVDV-2: 3 induced partial seroconversion

“The BVDV component of most vaccines does not induce consistent response against

BVDV-1, especially, to BVDV-2. It is evident that strategies for production of vaccines,

particularly to BVDV must be urgently revised.”

UFRGS’s veterinary virology laboratory – our work in pestiviruses

Pestivirus detection by RT-PCR

Genetic characterization

5’UTR, Npro and glycoprotein E2

Bioinformatics

Pestivirus detection by RT-PCR

Genetic characterization

5’UTR, Npro and glycoprotein E2

Bioinformatics

Pestivirus detection by RT-PCR

Genetic characterization

5’UTR, Npro and glycoprotein E2

Bioinformatics

Pestivirus detection by RT-PCR

Genetic characterization

5’UTR, Npro and glycoprotein E2

Bioinformatics

Pestivirus detection by RT-PCR

Genetic characterization

5’UTR, Npro and glycoprotein E2

Bioinformatics

Phylogenetic analysis Analysis of samples available in public database

• Follicular fluid: product obtained during in vitro embryo production

• BVDV in IVP systems can affect fertilization, embryonic development and infect the receptor cow

• 14/84 (16.7%) of FF positive for BVDV

• First report of a mucosal disease-like clinical presentation associated with a ‘HoBi’-like pestivirus occurring in a cattle herd

• The sequence and phylogenetic analysis of 5’NCR, Npro and E2 regions of the RT-PCR positive samples showed that four different ‘HoBi’-like strains of two different origins were circulating in the herd

• Performed together with the: Official Veterinary Service (SEAPA-RS and MAPA) Veterinary Epidemiology Laboratory (EPILAB-UFRGS)

• Samples collected during the FMDV State survey • 9,078 samples of calves from 6 to 12 months of age tested by RT-PCR= 33 positive

High frequency of BVDV-2: 42-45%

Similar to reported in Chile

Higher compared with other countries in the world

BDV was never reported in South America

Npro

Spatial distribution of the sampled farms investigated for the presence of ruminant pestiviruses in Rio Grande do Sul state, South Brazil. The cattle density and pestivirus species and subtypes are shown on the map.

• Homologous recombination is rarely reported in this virus family

• All complete pestivirus genomes that were available in GenBank were screened using distinct algorithms to detect genetic conversions and incongruent phylogenies

• Three putative recombinant viruses derived of recombination from different pestivirus subtypes/genogroups were detected

• Pestivirus classification cannot be based only on the analysis of one fragment of the genome because genetic conversions can lead to errors.

• Brazil: unique diversity of pestiviruses in circulation

89 isolates:

53.9% BVDV 1

33.7% BVDV 2

12.4% Hobi-like

• Apenas evidência sorológica previamente relatada • Javalis: alta população, ausência de predador, risco de disseminação de patógenos • Não devem ser excluídos dos controles de sanidade de pestivírus de bovinos

• Cepa altamente semelhante à identificada em bovinos no RS

• Ánálise da composição de quasispécies virais em Pis • Fatores individuais levam à seleção das variantes virais • Perda de quasispécie dominante no hospedeiro vivo

• Quasispecies composition in ‘HoBi’-like PI animals compared temporally; • Genetic variability in viral mutant clouds increased along time; • Absence of a putative N-glycosylation site represented an advantage in viral variants; • Variations in viral swarm occurred over time and were dependent on host factor.

Perspectives Detect and characterize pestiviruses from :

swine serum from the CSFV survey

cattle serum from the FMDV survey of the whole Brazilian territory

Perform serum neutralization with the 3 species to establish their relative

prevalence

Search for alternative native hosts

Search for atypical pestivirus: metagenomics

Development of a vaccine containing the antigenic types present in Brazil

Fitness of ruminant pestiviruses in Bos taurus and Bos indicus

Acknowledgments :