A Phylogeographic Analysis of Porcine Parvovirus 1 in Africa.

Porcine parvovirus 1 (PPV1) is recognized as a major cause of reproductive failure in pigs, leading to several clinical outcomes globally known as SMEDI. Despite being known since the late 1960s its circulation is still of relevance to swine producers. Additionally, the emergence of variants such as the virulent 27a strain, for which lower protection induced by vaccines has been demonstrated, is of increasing concern. Even though constant monitoring of PPV1 using molecular epidemiological approaches is of pivotal importance, viral sequence data are scarce especially in low-income countries. To fill this gap, a collection of 71 partial VP2 sequences originating from eight African countries (Burkina Faso, Côte d'Ivoire, Kenya, Mozambique, Namibia, Nigeria, Senegal, and Tanzania) during the period 2011-2021 were analyzed within the context of global PPV1 variability. The observed pattern largely reflected what has been observed in high-income regions, i.e., 27a-like strains were more frequently detected than less virulent NADL-8-like strains. A phylogeographic analysis supported this observation, highlighting that the African scenario has been largely shaped by multiple PPV1 importation events from other continents, especially Europe and Asia. The existence of such an international movement coupled with the circulation of potential vaccine-escape variants requires the careful evaluation of the control strategies to prevent new strain introduction and persistence.

Rabies Virus Seroprevalence among Dogs in Limpopo National Park and the Phylogenetic Analyses of Rabies Viruses in Mozambique.

Rabies is considered a neglected disease among many developing Asian and African countries, including Mozambique, where its re-emergence is often attributed to low dog parenteral vaccination coverage. The objectives of this study were two-fold: (1) to assess the level of antibodies against rabies virus in dogs (n = 418) in Limpopo National Park (LNP), and (2) to genetically characterise selected rabies viruses from brain tissue samples collected in 2017 and 2018. To meet the first objective, we used the BioProTM Rabies blocking ELISA antibody kit, and the results were expressed as the percentage of blocking (%PB). Dog sera with PB ≥ 40% were considered positive for antibodies to rabies virus, whereas sera with PB < 40% were negative. Just under ninety percent (89.2%; n = 373) of dogs were seronegative, and the rest (10.8%; n = 45) had detectable levels of rabies virus-specific antibodies. All eight brain tissue samples were positive for rabies virus antigen using a direct fluorescent antibody test and amplified in a quantitative real-time PCR, but only five (n = 4 from dogs and n = 1 from a cat) were amplified in a conventional reverse-transcription PCR targeting partial regions of the nucleoprotein (N) and the glycoprotein (G) genes. All samples were successfully sequenced. Phylogenetically, the rabies viruses were all of dog origin and were very closely related to each other (Africa 1b rabies virus lineage). Furthermore, the sequences had a common progenitor with other rabies viruses from southern Africa, confirming the transboundary nature of rabies and the pivotal role of dogs in maintaining rabies cycles. The study demonstrates the principal application of the BioProTM rabies ELISA antibody for the detection of anti-lyssavirus-specific antibodies in the serum samples of dogs, and most importantly, it highlights the low levels of antibodies against rabies virus in this dog population.

Identification of porcine circovirus-3 in Mozambique.

Porcine circovirus 3 (PCV-3) has been associated with an assortment of clinical conditions in pigs and has been reported in many countries worldwide. In Africa there is no data on the presence of PCV-3. In this study, DNA samples collected from 91 pigs between 2011 and 2019 in nine of the ten provinces of Mozambique in the context of African swine fever (ASF) monitoring were further screened for the presence of PCV-3. Of these samples, 7 (7.5%) animals were positive for PCV-3. Sequence and phylogenetic analysis of the capsid protein gene (ORF2) of the PCV-3s provided evidence of epidemiological links with PCV-3s identified in North and South America, Asia, and Europe. This is the first identification of PCV-3 in Mozambique (and Africa) and the first evidence of co-infection of PCV-3 and ASF virus. It should provide a starting point for further investigations into the presence and impact of PCV-3 in Africa.

Porcine circovirus-2 in Africa: Identification of continent-specific clusters and evidence of independent viral introductions from Europe, North America and Asia.

Porcine circovirus-2 (PCV-2) is associated with several disease syndromes in domestic pigs that have a significant impact on global pig production and health. Currently, little is known about the status of PCV-2 in Africa. In this study, a total of 408 archived DNA samples collected from pigs in Burkina Faso, Cameroon, Cape Verde, Ethiopia, the Democratic Republic of the Congo, Mozambique, Nigeria, Senegal, Tanzania and Zambia between 2000 and 2018 were screened by PCR for the presence of PCV-2. Positive amplicons of the gene encoding the viral capsid protein (ORF2) were sequenced to determine the genotypes circulating in each country. Four of the nine currently known genotypes of PCV-2 were identified (i.e. PCV-2a, PCV-2b, PCV-2d and PCV-2 g) with more than one genotype being identified in Burkina Faso, Ethiopia, Nigeria, Mozambique, Senegal and Zambia. Additionally, a phylogeographic analysis which included 38 additional ORF2 gene sequences of PCV-2s previously identified in Mozambique, Namibia and South Africa from 2014 to 2016 and 2019 to 2020 and available in public databases, demonstrated the existence of several African-specific clusters and estimated the approximate time of introduction of PCV-2s into Africa from other continents. This is the first in-depth study of PCV-2 in Africa and it has important implications for pig production at both the small-holder and commercial farm level on the continent.

Enhanced diagnosis of rabies and molecular evidence for the transboundary spread of the disease in Mozambique.

Rabies is a neglected zoonotic disease with veterinary and public health significance, particularly in Africa and Asia. The current knowledge of the epidemiology of rabies in Mozambique is limited because of inadequate sample submission, constrained diagnostic capabilities and a lack of molecular epidemiological research. We wanted to consider the direct, rapid immunohistochemical test (DRIT) as an alternative to the direct fluorescent antibody (DFA) for rabies diagnosis at the diagnostic laboratory of the Central Veterinary Laboratory (CVL), Directorate of Animal Science, Maputo, Mozambique. Towards this aim, as a training exercise at the World Organisation for Animal Health (OIE) Rabies Reference Laboratory in South Africa, we performed the DRIT on 29 rabies samples from across Mozambique. With the use of the DRIT, we found 15 of the 29 samples (52%) to be negative. The DRIT-negative samples were retested by DFA at the OIE Rabies Reference Laboratory, as well as with an established real-time Polymerase chain reaction, confirming the DRIT-negative results. The DRIT-positive results (14/29) were retested with the DFA and subsequently amplified, sequenced and subjected to phylogenetic analyses, confirming the presence of rabies RNA. Molecular epidemiological analyses that included viruses from neighbouring countries suggested that rabies cycles within Mozambique might be implicated in multiple instances of cross-border transmission. In this regard, our study has provided new insights that should be helpful in informing the next steps required to better diagnose, control and hopefully eliminate rabies in Mozambique.